Book - Buchanan's Manual of Anatomy including Embryology 11

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I have decided to take early retirement in September 2020. During the many years online I have received wonderful feedback from many readers, researchers and students interested in human embryology. I especially thank my research collaborators and contributors to the site. The good news is Embryology will remain online and I will continue my association with UNSW Australia. I look forward to updating and including the many exciting new discoveries in Embryology!

Frazer JE. Buchanan's Manual of Anatomy, including Embryology. (1937) 6th Edition. Bailliere, Tindall And Cox, London.

Buchanan's Manual of Anatomy: I. Terminology and Relative Positions | II. General Embryology | III. Osteology | IV. Bones of Trunk | V. Bones of Head | VI. Bones of Upper Limb | VII. Bones of Lower Limb | VIII. Joints | IX. The Upper Limb | X. Lower Limb | XI. The Abdomen | XII. The Thorax | XIII. Development of Vascular Systems | XIV. The Head and Neck | XV. The Nervous System | XVI. The Eye | XVII. The Ear | Glossary
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Chapter XI The Abdomen

Male Perineum

Landmarks. —The ischial tuberosity can be felt on either side, as we as the ischio-pubic ramus; but the sacro-tuberous ligament cannot b felt, on account of the thickness of the lower border of the glutei] maximus. The posterior margin of the pubic symphysis and th tip of the coccyx are both to be felt, the former, however, only on dee pressure.

The perineum practically corresponds with the outlet of the pelvi* and is somewhat lozenge-shaped, having the subpubic angle in from

the tip of the coccy behind, and the ischk tuberosity on eithe side. It is convenient! divided into two part by a line connectin the ischial tuberosities each division being tri angular. The anterio constitutes the urc genital division, thi being the perineur proper, and the pos terior the anal divisior The skin of the uro genital division present an antero-posterior me dian elevation, calle< the perineal raphe which extends over th' posterior and anterior surfaces of the scrotum, and along the unde surface of the penis, indicating the bilateral origin of these parts The position of the deeply-placed perineal body is indicated by taking a point in this raphe about an inch in front of the anus.

The anus is the external opening of the anal canal. It is situatec posterior to a line connecting the front parts of the ischial tuberosities and about inches from the tip of the coccyx. A delicate white lin< surrounds the anus where the skin and mucous membrane meet; i indicates the interval between the external and internal sphinctei


Fig. 404.—Lower Aperture of Male Pelvis.

SP, subpubic ligament; ST, sacro-tuberous ligament; T, tuber ischii.


muscles (Hilton). The position of each ischio-rectal fossa is indicated y a slight depression between the anus and ischial tuberosity.

Deep Boundaries of the Perineum— Anterior. — The subpubic angle id the inferior pubic ligament. Posterior. —The coccyx. Lateral .— rom behind forwards, the inferior border of the sacro-tuberous ligalent, the ischial tuberosity, and the ischio-pubic ramus.


Ischio-rectal Division.

Cutaneous Nerves. —These are (1) the perineal branch from the iwer part of the anterior primary division of the fourth sacral, and

) the inferior hsemorrhoidal nerve, a branch of the pudendal. The >rmer supplies the skin between the tip of the coccyx and the anus, le latter the skin around the anus as far out as the ischial tuberosity.

Fascia. —The superficial fascia of this division is rich in fat, and is rolonged into the ischio-rectal fossa, where it forms an elastic pad on hich the pelvic floor rests.

Ano-coccygeal Body. —This is a collection of fibrous and muscular ssue situated between the coccyx and anal canal, the muscular ement being contributed by the levatores ani and sphincter ani luscles. Its importance lies in the fact that it gives support to the nal canal.

Muscles. —The muscles in this division are the corrugator cutis ani, dhncter ani externus, levator ani, and coccygeus.

Corrugator Cutis Ani (Ellis). —This muscle is represented by a very elicate sheet of involuntary muscular fibres, which pass in a radiating tanner from the submucous tissue of the anal aperture to be inserted tto the surrounding skin.

Action. —(1) To throw the skin around the anus into wrinkles; and ’) to invert the mucous membrane of the lower end of the anal canal her it has been everted during defsecation.

For the levator ani and coccygeus, see pp. 947 and 948.

Sphincter Ani Externus — Origin. —The tip of the coccyx and the bn over it.

Insertion .—The greater part of the muscle is inserted into the erineal body. The more superficial fibres, however, are inserted ho the skin, and a certain amount of decussation takes place across ie middle line.

N erve-supply .—The part of the muscle between the coccyx and ie anus is supplied by the perineal branch of the fourth sacral, the ^mainder by the inferior hsemorrhoidal and the muscular branch of the erineal nerve, both of which are derived from the pudendal.

Action .—To keep the anal aperture closed, at the same time proving a wrinkled condition of the skin.

The muscle is situated immediately beneath the skin, and is liptical. Behind and in front of the anus it is single, but around iat aperture it is arranged in two symmetrical halves, which are itimately connected with the middle portions of the levatores ani.


Ischio-rectai Fossa. —This is a deep fossa which is situated 0 either side between the ischium and rectum. It measures near! 2J inches in depth, 2 inches from before backwards, and 1 inch froi side to side. In transverse section it is triangular, the base bein directed downwards and the apex upwards. The outer wall, which vertical, is formed by the lower part of the obturator internus muse covered by the obturator fascia. The inner wall, which is oblique, formed by the lower part of the rectum, the anal canal, the levatc ani muscle covered by the anal fascia, and the sphincter ani externu The base is formed by the skin and fascia, which extend between th


Fig. 405. —Dissection of the Male Perineum. On the left side the bulbo-spongiosus has been removed and the crus penis cut.

ischial tuberosity and anus. The roof is just below the white line where the anal fascia springs from the obturator fascia. Anteriorly the fossa is partially limited by the deep layer of superficial perinea fascia as it is reflected round the posterior border of the superficia transverse perineal muscle on its way to join the base of the perinea membrane. Above this junction there is a forward prolongation o the fossa, called the anterior diverticulum , which extends almost U the symphysis pubis; it lies between the superior layer of the perinea membrane and the inferior surface of the anterior part of the levatoi ani muscle, and is limited by the prostate gland and pubo-prostatic ligament medially, and by the ischio-pubic ramus laterally. Posteriorly the fossa is partially limited by the margin of the sacro-tuberous igament and the lower border of the gluteus maximus muscle. Beween these two structures it is prolonged backwards for a short [istance in the form of a posterior diverticulum, which extends outwards owards the ischial tuberosity, and inwards towards the upper part if the coccyx.

Position of Contents. —The internal pudendal vessels and the >erineal and dorsal nerve of penis, branches of the pudendal nerve, lie n the pudendal canal, which runs along the outer wall 1J inches above he lower part of the ischial tuberosity. The inferior rectal vessels ,nd nerve cross the fossa transversely from the outer wall to the anal

anal. The perineal vessels and nerves, branches respectively of the nternal pudendal vessels and of the perineal branch of the pudendal lerve, lie for a short distance, as they run forwards, in the front part >f the fossa, where they anastomose and form connections with branches )f the inferior rectal vessels and the inferior haemorrhoidal nerve. At he back part of the fossa, winding round the lower border of the gluteus naximus, the gluteal cutaneous branches of the posterior cutaneous lerve of thigh and the inferior gluteal artery, as well as the perforating

utaneous branch from the sacral plexus, are to be seen. The fossa is filled with loose fat, which also extends into the anterior ind posterior diverticula.

This fat is badly supplied with bloodvessels, and its vitality is therefore low. \.s a consequence, an ischiorectal abscess is of not infrequent occurrence. When m abscess forms, the pus has a tendency to discharge itself in two directions— lamely, through the skin forming the floor of the fossa, and through the wall of

he anal canal about inch above the anus. If the discharge is effected in either )r both of these two ways a fistulo in ano is the result.

The severe pain which accompanies an ischio-rectal abscess is due to pressure lpon the following nerves: (1) the inferior haemorrhoidal; (2) the two superficial lerineal nerves; and (3) the gluteal cutaneous branches of the posterior cutaneous lerve of thigh.


Uro-genital Division.

Superficial Fascia. — The superficial fascia resembles that over the ower part of the anterior wall of the abdomen in being divisible into

wo layers, which are called the superficial layer and the deep layer. The superficial layer contains a granular variety of fat which is n sharp contrast with the lobulated fat of the ischio-rectal division. When followed backwards it forms on either side the floor of the Lschio-rectal fossa. At the middle line it is continuous with the corresponding layer of the, opposite side. Laterally it passes freely over the ischio-pubic ramus, and is continuous with the superficial fascia of the inner side of the thigh. Anteriorly it passes into the scrotum, where it joins the deep layer. The resultant fascia, now free from adipose tissue, contains involuntary muscular tissue, and forms the iartos muscle. The superficial layer represents the superficial fascia of the anterior abdominal wall.

The deep layer (Fascia of Colles) is membranous and strong.


Laterally it is attached to the anterior everted lip of the inner horde of the ischio-pubic ramus as far back as the ischial tuberosity, in mediately outside the attachment of the crus penis. Medially tt fascia of one side is continuous with that of the other at the middl line. Posteriorly the fascia turns round the posterior border of eac superficial transverse perineal muscle, and joins the base of the perine; membrane. Anteriorly it passes into the scrotum, where it joins tt superficial layer, the two forming the dartos muscle.

The deep layer of superficial perineal fascia represents the dee fascia of the anterior abdominal wall. It forms in the erect positic the floor of a space called the perineal pouch. This pouch is partial] subdivided into two compartments by an incomplete septum, whic extends upwards from the deep or superior surface of the deep lay( of superficial perineal fascia to be attached to the overlying perine; membrane. This septum is only complete at the back; elsewhere is very imperfect.

When air is blown beneath the back part of the deep layer of supei ficial perineal fascia on one side of the middle line, the perineal pouc of that side and the corresponding half of the scrotum become di; tended. As more air is blown in, the pouch of the opposite side an the corresponding half of the scrotum also become distended.

It is into the perineal pouch that urine is extravasated in rupture of the urethi in the perineum. In such cases the urine cannot pass into either ischio-rect; fossa, its backward course being arrested at the posterior borders of the superfici; transverse perineal muscles, where the deep layer of superficial perineal fascia, £ a whole, turns round to join the base of the perineal membrane. Neither ca: the urine make its way down the inner side of the thigh, its passage in th: direction being stopped at the ischio-pubic ramus, to which the deep layer c superficial perineal fascia is attached. The only course, therefore, which is ope to the extravasated urine is forwards into the scrotal wall and on to the peni in each case beneath the dartos muscle, whence it passes upwards along th spermatic cord to the anterior wall of the abdomen, in which situation it lie beneath the deep fascia.

The deep layer of superficial perineal fascia covers the followin structures: the crura penis, covered by the ischio-cavernosus muscles the bulb of the penis, covered by the bulbo-spongiosus muscles; th superficial transverse perineal muscles; the superficial perineal vessel of each side; the two superficial perineal nerves and the long perinea nerve; the terminal branches of the deep division of the perineal branc of the pudendal nerve to the superficial perineal muscles, the bull and urethra; the terminal branches of the dorsal penis branch of th pudendal nerve to the corpus cavernosum and penis; and the inferio layer of the perineal membrane.

Muscles—Transversus Perinaei Superficial^ (Fig. 406)— Origin.The ramus of the ischium superficial or deep to the ischio-cavernosus.

Insertion .—The perineal body.

Nerve-supply .—The deep division of the perineal branch of th pudendal nerve.


Action .—To draw back and fix the perineal body, and so to aid he action of the bulbo-spongiosus.

The muscle is directed obliquely inwards and forwards, being ccompanied by the transverse perineal artery, and being crossed uperficially or deeply by the superficial perineal nerves. It forms he base of a triangle, the other two sides being formed by the bulbopongiosus and ischio-cavernosus muscles.

Ischio-cavernosus (Erector Penis) — Origin. —(1) The inner aspect f the ischial tuberosity; and (2) the inner border of the ramus of the schium on either side of the crus penis.


Fig. 406. —Superficial Dissection to show Perineal Muscles and

ISCHIO-RECTAL FOSSA.


Insertion .—The under surface of the fibrous sheath of the crus Denis in its front part, and the outer and upper surfaces of the fibrous sheath of the corpus cavernosum penis, in which latter situation it is continuous with the fascial investment of the penis and with the suspensory ligament of that organ.

Nerve-supply .—The deep division of the perineal branch of the pudendal nerve.

Action .—The muscle compresses the crus penis against the ischiopubic ramus, and, by retarding the return of venous blood, it helps to maintain the penis in a state of erection. It also contributes to the maintenance of erection by compressing the dorsal vein of the penis.


The anterior and outer part of the muscle is sometimes detached, and forn a separate muscle, called the compressor venae dorsalis penis. This arises froi the descending ramus of the- pubis, and terminates in an aponeurotic expansio which joins its fellow of the opposite side over the dorsal vein of the penis.

Bulbo-spongiosus (Fig. 406) (Accelerator or Ejaculator Urinse) Origin. —(1) The perineal body; and (2) the median raphe, which j continued forwards from that point towards the symphysis pubis.

Insertion .—The muscle, as regards its insertion, is convenientl divided into three parts—namely, the chief part, the anterior par and the posterior part.

Chief Part. —The fibres of this part ascend between the crus pen: and the side of the bulb, to be inserted into the medi'an raphe on tb upper surface of the bulb, where they meet the fibres of the corn sponding part of the opposite muscle.

Anterior Part. —The fibres of this part as they pass forward diverg in the form of a V and are inserted partly into the outer surface of tb fibrous sheath of the corpus cavernosum penis in front of the ischic cavernosus, and partly by means of a tendinous expansion into tb fascial investment of the penis, beneath which the dorsal vein of th penis lies; they are sometimes regarded as forming a separate musclethe constrictor radicis penis.

Posterior Part. —The fibres of this, which is also the deepest pari surround like a close-fitting cap the hemispheres of the bulb, and ar inserted into the dorsal surface of the bulb immediately in front c the point of entry of the urethra.

Nerve-supply .—The deep division of the perineal branch of th pudendal nerve.

Action. —(1) The chief part of the muscle, acting with its fellow compresses the bulb. These portions of the two muscles therefor come into play at the end of micturition, when they expel the las drops of urine from this part of the urethra. A further action is t contribute to the maintenance of erection of the penis by compressin the veins of the bulb. (2) The anterior part compresses the dorse vein of the penis, and so contributes to the maintenance of erectior (3) The posterior part, when in action, will compress not merely th hemispheres of the bulb and their bloodvessels, but also the urethr and the ducts of the bulbo-urethral glands.

The chief portions of the bulbo-spongiosus muscles complete! surround the bulb, and may be regarded as forming a sphincter muscle

Sphincter (Compressor) Urethrae— Origin. —From the inner boreie of the inferior ramus of the pubis, lying behind or above the inferio layer of the perineal membrane.

Insertion. —Near the middle line the muscle divides into two layers which, passing above and below the membranous part of the urethra are inserted into median raphes, thus constituting a sphincter muscle The lower layer, which is by far the better developed, ensheathe also the bulbo-urethral glands. The posterior fibres of the muscle which lie close to the base of the perineal membrane, are sometime regarded as a separate muscle—the deep transverse muscle of the perineum.

Nerve-supply .— The dorsal nerve of the penis.

Action. —(i) To constrict the membranous part of the urethra, rhe muscle comes into play at the end of micturition, and assists the Dulbo-spongiosus in emptying the urethral canal. (2) To contribute

o the maintenance of erection of the penis by compressing the veins rom the corpora cavernosa and bulb. (3) To compress the bulborrethral glands, and so aid in the expulsion of their secretion.


Fig. 407. — Deep Dissection of the Male Perineum. The rectum has been turned back.


The sphincter urethrae muscle lies between the two layers of the perineal membrane. Close to its attachment to the ischio-pubic ramus -t contains within its substance the internal pudendal vessels and the iorsal nerve of the penis.

Perineal Body (Central Tendinous Point). —Nearly 1 inch in front of the anus there is a short transverse tendinous septum about J inch tong. At its centre it presents a thickening, to which the name of berineal body is given. The muscles which meet at this point are as follows: (1) the sphincter ani externus, coming from behind; (2) the bulbo-spongiosus, coming from before; (3) the superficial transverse perineal muscles, coming from either side; and (4) the levatores ani, coming from above. The pointed process at the centre of the base of the inferior layer of the perineal membrane is also attached to the perineal body.

Bulb of the Penis. —This is the first part of the corpus spongiosun penis, and is so named from its presenting a bulbous enlargement. Ii measures about if inches in length, and about § inch in breadth ai its posterior part. Its posterior extremity rests upon the inferioi layer of the perineal membrane, and extends as far back as the perinea body, where it lies nearly i inch in front of the anus. This par extends fully J inch farther back than the bulbous part of the urethra It here presents on its under surface, in the middle line, a faint groov( indicative of its having been formed by the union of two symmetrica parts. The bulb is invested by a fibrous sheath derived from th( circumference of the urethral opening in the inferior layer of the perinea membrane, superficial to which lie fibres of the bulbo-spongiosu: muscles. Each lateral wall of the bulb is pierced by the duct of the bulbo-urethral gland, which opens on either side of the middle lin< upon the floor of the bulbous part of the urethra fully i inch in fron of the inferior layer of the perineal membrane.

Crus Penis (Crus Corporis Cavernosi Penis). —This is the posterio] attached portion of the corpus cavernosum penis. It occupies and i: attached to a broad groove which, beginning near the ischial tuberosity winds spirally round the inner border of the ischio-pubic ramus super ficial to the inferior layer of the perineal membrane. Interiorly anc laterally it is covered by the ischio-cavernosus and lies beneath th< deep layer of superficial perineal fascia. The deep artery of the penis having pierced the inferior layer of the perineal membrane, enter: the deep surface of the crus, to be continued forwards in the centre o: the corpus cavernosum.

Deep Perineal Triangle—Boundaries — Lateral .—The crus penis covered by the ischio-cavernosus muscle. Medial .—The bulb of th( penis, covered by the bulbo-spongiosus muscle. Posterior, or Base.— The superficial transverse perineal muscle. The floor is formed by the deep layer of superficial perineal fascia, with the superficial perinea vessels and nerves. In the undisturbed position of the parts the are«  of the triangle is concealed by the approximation of the bulbo-spongiosu: and ischio-cavernosus muscles. When, however, these muscles an held apart there is seen lying deeply in the area the inferior layer of the perineal membrane.

Inferior Ligament of Symphysis Pubis (Arcuate Ligament). —This i: a thick band which lies at the antero-superior part of the pubic arch It is attached superiorly to the lower part of the fibro-cartilaginou: disc, and laterally to the adjacent parts of the inner lips of the inferior pubic rami. It is about J inch in depth, and is slightly arched.

Transverse Ligament of Perineum. —This band extends transversely between the inferior pubic rami two or three lines below the inferioi ligament of symphysis. Inferiorly it is closely connected with the truncated apex of the inferior layer of the perineal membrane. Between its upper border and the inferior ligament there is the opening or the backward passage of the dorsal vein of the penis.

Perineal Membrane (Triangular Ligament) (Fig. 408).—This ligament >ccupies the pubic arch, which it fills, except at its antero-superior part, vhere it is replaced by the inferior and transverse perineal ligaments! t is composed of two distinct layers, called inferior (perineal) and uperior (pelvic). These two layers are united by their bases, but elsewhere they are separated by an interval of about J inch, in which he membranous part of the urethra in the male, and the vagina and irethra in the female, along with other structures to be presently aiumerated, lie.

The inferior layer is also called the deep perineal fascia. It is triangular, the apex being truncated. The apex is closely connected with the transverse perineal ligament, which may be regarded as a >art of it. Each lateral margin is attached behind or to the posterior edge of the inner border of the ischio-pubic ramus, on which it extends as far back as the ischial tuberosity, lying between the attachments )t the crus penis and ischio-cavernosus anteriorly and the sphincter irethrae posteriorly. In this direction it measures fully 2 inches, me base is directed downwards and backwards, and is joined by the )ase of the postero-superior layer and the deep layer of superficial )ermeal fascia. In the middle line the base is projected into a slight irocess, which is connected with the perineal body. On either side of his median process the base presents a concave margin where it sweeps iownwards and outwards to the ischial tuberosity. The length of the 'Vfl° r l a y er * n the middle line is about ij inches. Its fibres are Tiefly disposed transversely. The structures which pierce this layer are as follows: the urethra, the arteries of the bulb, the deep arteries of the penis, the dorsal arteries and the dorsal nerves of the penis, the superficial perineal vessels and nerves, and the ducts of the bulbourethral glands.


Fig. 408. — The Perineal Membrane. The antero-inferior layer has been removed on the left side.




Urethral Opening. — This aperture is situated in the middle line fully i inch below the pubic angle. From the circumference of the opening an extension is given off, which forms a fascial investment for the bulb.

Openings for the Arteries of the Bulb. —These are situated one on

either side of the urethral opening.

Openings for the Deep Arteries of the Penis. —These are found near the lateral attached border, under cover of the crus penis, about i inch below the level of the pubic angle.

Openings for the Dorsal Arteries and Nerves of the Penis. —These are two in number on either side, and are situated far forward, near the pubic angle, and close to the inferior pubic ramus, the opening for the artery being medial to that for the nerve. It is to be noted that the dorsal vein of the penis has a special opening, which is situated in the median line between the inferior and transverse perineal ligaments.

Openings for the Superficial Perineal Vessels and Nerves . These are situated on either side, in the base at the line of junction with the deep layer of superficial perineal fascia.

Openings for the Ducts of the Bulbo-urethrat Glands. —Each of these is situated on either side of the urethral aperture a little behind and below the opening for the artery of the bulb.

Chief Relations — Antero-inferior. —The bulb of the penis and the crura penis, covered by their respective muscles, the superficial transverse perineal muscles, and the deep layer of superficial perineal fascia. Postero-superior. —The membranous part of the urethra, the bulbourethral glands, and the sphincter urethrae muscle.

The superior layer is weak, and is formed by the parietal pelvic fascia. It lies about \ inch above and behind the inferior layer, and extends inwards to the urethra from the back of each ischio-pubic ramus, where it lies behind the sphincter urethrae muscle. Anteriorly it blends with the sheath of the prostate posteriorly; its base joins that of the inferior layer. At each ischio-pubic ramus it is continuous with the parietal pelvic fascia. When it arrives at the urethra it changes its course, and passes backwards over the anterior border of the levator ani muscle to blend with that portion of the visceral pelvic fascia which ensheathes the prostate gland. Antero-inferiorly it is in contact with the membranous part of the urethra and sphincter urethrae muscle, whilst postero-superiorly it is related to the anterior fibres of the levator ani of each side, and forms the floor of the anterior diverticulum of the ischio-rectal fossa. The structures which pierce this layer are as follows: the urethra in the male, and the vagina and urethra in the female; and the internal pudendal vessels and dorsal nerves of the penis.

Urethral Opening. — This is often a mere cleft, in which case the superior layer may be described as being arranged in two symmetrical halves. At this opening or cleft it becomes continuous superiorly with the capsule of the prostate gland.

Openings for the Internal Pudendal Vessels and Dorsal Nerves of the Penis .—These are situated close to the base, on either side, near the ischial ramus.

Much of the difficulty which the student experiences in understanding the anatomy of the perineum is due to the fasciae or so-called ligaments which divide the region into compartments. These fasciae are to be regarded as due to the strain thrown upon the connective tissue which everywhere surrounds here, as elsewhere, muscles, bloodvessels, glands, and other structures. In the perineum the connective tissue is particularly exposed to strain owing to its position and the support which it is called upon to give to various structures, some of which pass through it, and several of which are subject to considerable variations in size. Naturally individual differences are met not merely in the development of these fasciae, but also in the relation which they bear to the vessels and nerves. The student is advised to obtain a clear general idea of the course of the various vessels and nerves, and of their respective branches, and to remember that they are but little, if at all, deflected from a direct course to their destination.

Structures between the Layers of the Perineal Membrane.— These are as follows:

  1. The membranous portion of the urethra in great part.
  2. The bulbo-urethral glands..
  3. The sphincter urethrae muscle.
  4. The internal pudendal arteries, each lying close to the ischiopubic ramus in the sphincter urethrae muscle, and each giving off the following branches: (a) the artery of the bulb, which in turn gives off the artery to Cowper’s gland; ( b ) the deep artery of the penis; and (c) the dorsal artery of the penis.
  5. A plexus of veins which receives its tributaries from the crus (corpus cavernosum) and bulb, and in which the internal pudendal venae comites take their origin.
  6. The deep lymphatics of the penis and urethra.
  7. The dorsal nerves of the penis, each of which lies lateral to the corresponding internal pudendal artery.


Bulbo-urethral Glands (Cowper’s)

These glands are two in number, right and left. They are situated between the two layers of the perineal membrane, where they lie above the bulb and behind the membranous portion of the urethra, one on either side of the median line. Each gland is a firm, round, and lobulated mass about the size of a small pea. Both glands are ensheathed by the lower layer of the sphincter urethrae muscle, and within this there is the special fibrous capsule which has an admixture of plain muscular tissue. The glands belong to the class of racemose or acino-tubular glands, and each is composed of several lobules. The alveoli or acini are lined with columnar cells. The ducts are two in number, right and left. They are lined with cubical epithelium, and their walls contain plain muscular tissue.


Each duct pierces the inferior layer of the perineal membrane on eithe side of the urethral opening a little behind and below the artery of th bulb. The duct then pierces the side of the bulb, and opens upon th floor of the bulbous part of the urethra fully i inch in front of the ir ferior layer of the perineal membrane. Each gland receives a branc' from the artery of the bulb.


The bulbourethral glands are developed from the epithelial lining of the urc genital sinus.


Fig. 409.— Plan of Left Internal Iliac Artery.


Internal Pudendal Artery. —This vessel is one of the terminal branches of the anterior division of the internal iliac, the other and larger terminal branch being the inferior gluteal. Lying at first within the pelvis, the artery passes downwards over the pyriformis muscle and sacral nerves, having the inferior gluteal artery usually behind it, and it emerges from the cavity through the lower compartment of the greater sciatic foramen. It then crosses the back of the spine of the ischium, after which it passes through the lesser sciatic foramen, and so enters the ischio-rectal division of the perineum. The vessel now courses along the outer wall of the ischio-rectal fossa, where, contained in the pudendal canal, it lies about ij inches above tie lower part of the ischial tuberosity. On approaching the anterior art of the fossa the artery gradually becomes more superficial, and, fter leaving the fossa, it enters the interspace between the two lyers of the perineal membrane by piercing the superior layer close d its base and near the ischial ramus. It now passes forwards and pwards, embedded in the sphincter urethrae muscle, and lying close d the ischio-pubic ramus, where it is comparatively superficial, laving given off the artery of the bulb about f inch above the base of fe perineal membrane, the vessel finally divides, about 1 inch below fe subpubic angle, into its two terminal branches, the deep and dorsal rteries of the penis.

In considering the relations and branches of the internal pudendal rtery it is convenient to divide the vessel into four parts—first, second, aird, and fourth.


The first part represents the intrapelvic portion of the vessel, and all be found described on p. 925.

The second part is the portion of the vessel which lies upon the ack of the spine of the ischium. For a description of it see p. 539.

The third part is the part of the vessel which lies on the outer adl of the ischio-rectal fossa. It is here contained in the pudendal anal, and is situated about if inches above the lower part of the

chial tuberosity. For its relation see the pudendal canal. Branches. —These are as follows: the inferior rectal, the superficial erineal, and the transverse perineal.

The inferior rectal (hsemorrhoidal) artery arises, either singly or 1 two or three branches, from the internal pudendal immediately after

h as taken up its position in the pudendal canal. The branches pass lwards to the anal canal through the loose fat which fills the ischiosctal fossa. They are distributed to the external sphincter, levator ni, wall of the anal canal, and superficial structures of the ischiosctal division of the perineum, and they anastomose with the middle nd superior rectal arteries and the inferior rectal branches of the pposite side.


The superficial perineal artery arises from the internal pudendal at ae anterior part of the ischio-rectal fossa. It pierces the base of tie inferior layer of the perineal membrane, and passes superficial 3 (sometimes on the deep surface of) the superficial transverse perineal luscle. Its subsequent course is forwards under cover of the deep iyer of superficial perineal fascia, on the floor of the deep perineal uangle, in company with the superficial perineal nerves. On approach*g the scrotum it divides into several long slender branches, which a PPty the back of the scrotum and anastomose with the external udendal branches of the femoral artery.

The transverse perineal artery, as a rule, arises in common with superficial perineal, of which it is sometimes regarded as a branch, t may, however, arise directly from the internal pudendal immediately 1 front of the origin of the superficial perineal. It is directed inwards and forwards to the perineal body, lying superficial to the superfici transverse perineal muscle, and beneath the deep layer of superfici perinea] fascia. It supplies the muscles which meet at the perine body, and anastomoses with its fellow of the opposite side.

The Pudendal (Alcock’s) Canal. —This canal is situated in the out* wall of the ischio-rectal fossa, and is formed by the obturator fasci Its contents from below upwards are as follows: (i) the perineal divisic of the pudendal nerve; (2) the third part of the internal pudendal artei with its venae comites; and (3) the dorsal nerve of the penis.

The fourth part of the internal pudendal artery lies between tl two layers of the perineal membrane. It enters this interspace t piercing the superior layer of that membrane close to its base ar near the ischial ramus. It is embedded in the sphincter urethr muscle, and is comparatively superficial. As it lies near the ischii pubic ramus it has a vena comes on either side of it, and the dors; nerve of the penis is lateral to it.

Branches. —These are as follows: the artery of the bulb, the dee artery of the penis, and the dorsal artery of the penis.

The artery of the bulb arises from the internal pudendal about \ inc above the base of the perineal membrane, and passes transverse] inwards in the substance of the sphincter urethrae muscle. On a] proaching the urethra it turns forwards, and, having pierced tl sphincter urethrae, it passes through an opening in the inferior lay* of the perineal membrane at the side of the urethral aperture. ] then enters the bulb, and is continued onwards in the corpus spoi giosum as far as the glans penis, the erectile tissue of which parts supplies. It anastomoses with its fellow of the opposite side and wit the dorsal arteries of the penis; whilst between the two layers of tl perineal membrane the artery furnishes a branch to the bulbo-urethr; gland of the corresponding side.

The deep artery of the penis is one of the two terminal branches ( the internal pudendal, and is somewhat larger than the dorsal arter of the penis, which is the other terminal branch. It arises abor 1 inch below the subpubic angle, and piercing the sphincter urethr muscle and the inferior layer of the perineal membrane close to th ischio-pubic ramus, enters the crus on its inner surface. Giving a fe 1 branches backwards, it is continued forwards in the centre of the corpr ca,vernosum as far as the distal end of that body, the erectile tissue c which it supplies.

The dorsal artery of the penis is the continuation of the interne pudendal. For a very short distance it lies between the two layei of the perineal membrane embedded in the sphincter urethrae musclt Piercing this muscle and the inferior layer of the membrane near it upper part, it ascends between the crus and the symphysis pubis Its subsequent course is between the two layers of the suspensor ligament of the penis, and then along the dorsum of the organ, wher it has the centrally-placed dorsal vein on its inner side and the dorsa nerve of the penis on its outer. On arriving at the neck of the penis ends in branches for the supply of the glans and prepuce, anastomosing th its fellow of the opposite side and the arteries of the bulb. In its urse along the dorsum of the penis the artery gives off many branches, me of which supply the skin and anastomose with the superficial

ternal pudendal of the femoral, while others pierce the fibrous sheath the corpus cavernosum to supply its erectile tissue, these latter Lastomosing with the deep artery of the penis.

Varieties of the Internal Pudendal Artery—1. Trunk. —The vessel is occasionly of small size, and may terminate in the artery of the bulb, or in the superial perineal artery. In these cases an accessory pudendal artery is present, lich supplies the deficiencies. This vessel usually arises from the first or trapelvic part of the internal pudendal, though it may spring from an inferior

sical artery. Its course is forwards along the side of the bladder, then along e side of the prostate gland to the perineal membrane, which it pierces above e membranous part of the canal, and so reaches the root of the penis. The cessory pudendal furnishes the deep artery of the penis and the dorsal artery of e penis, and in some cases the artery of the bulb.

2. Artery of the Bulb. —Sometimes two arteries are present on one side; metimes the artery is absent on one side; and sometimes it is of very small le. A much more important variety of this artery affects its origin. It may ise from the third part, at ±he front of the ischio-rectal fossa, reaching the bulb Dm behind. In these cases the artery cannot escape division in the operation

lateral lithotomy. In other cases it may arise from an accessory pudendal tery, when it will lie farther forwards than usual.

3. Dorsal Artery of the Penis. —This vessel may arise from the obturator tery in the obturator canal, or from one of the external pudendal branches of ie femoral artery.

Veins. —Lying in each sphincter urethrae muscle there is a plexus

veins, which receives its tributaries from the corresponding corpus ivernosum and one half of the corpus spongiosum and bulb. The iternal pudendal venae comites arise on either side from this plexus, id accompany the internal pudendal artery as far back as the upper irder of the spine of the ischium, one lying on either side of the essel. Here they join to form one trunk, which enters the pelvis irough the lower compartment of the greater sciatic foramen, and irminates in the internal iliac vein. They receive as tributaries the 'ansverse perineal, superficial perineal, and inferior rectal veins, as ell as a few veins from the gluteus maximus and lateral rotator muscles, he inferior rectal (hsemorrhoidal) veins take their origin in a plexus f veins which is situated immediately underneath the mucous memrane of the anal canal. Having pierced the external sphincter muscle, ley cross the ischio-rectal fossa through its loose fat and, being ultilately reduced to two or three in number, join the internal pudendal enae comites.

It is to be noted that, though there are two dorsal arteries, there > only one dorsal vein, which takes the following course: after leaving tie dorsum of the penis it passes through an opening between the in^rior and transverse perineal ligaments, where it communicates on tiller side with the venous plexuses from which the internal pudendal eins take their origin. Having entered the cavity of the pelvis, it divides into two branches, right and left, which join the prostat plexus of veins.

Lymphatics. —The superficial lymphatics of the perineum, includii those of the anus, pass to the superficial inguinal glands , which 1 immediately below the inguinal ligament, while the deep lymphatl accompany the internal pudendal vessels through the ischio-rectal fos; and buttock into the pelvis and pass to the internal iliac glands.

Pudendal Nerve. —The pudendal nerve is one of the termin branches of the sacral plexus, and derives its fibres from the ventr division of the second, the lower branch of the third, and the upp<


Scrotum


Deep Layer of Superficial Perineal Fascia (right half)


Superficial Perinealf Nerves f


Long Perineal Nerve


Superficial Transverse Perineal Muscle


Inferior Hasmorrhoidal Nerve


Gluteal Cutaneous Branches of Posterior Cutaneous Nerve of Thigh


Perforating Cutaneous Nerve


-Perineal Body

-Superficial Perineal Artery

-Transverse Perineal Artery

__ Internal Pudendal Artery ii the Pudendal Canal V— Inferior Rectal Artery


- Gluteal Cutaneous Branche: of Inferior Gluteal Artery


Perineal Branch of 4th Sacral Nerve

Fig. 410.—Dissection of the Male Perineum.

On the left side the bulbo-spongiosus has been removed and the crus


penis cut.


branch of the fourth sacral nerves, the majority of its fibres bein derived from the lower branch of the third. Leaving the pelvi through the lower compartment of the greater sciatic foramen, th nerve crosses the sacro-spinous ligament near its attachment to th spine of the ischium, lying under cover of the gluteus maximus an* on the inner side of the internal pudendal vessels. It then passe through the lesser sciatic foramen, and so enters the pudendal cana in the outer wall of the ischio-rectal fossa. Immediately after doinj so, it divides into three branches—namely, inferior haemorrhoidal perineal, and dorsal nerve of the penis.


The inferior hsemorrhoidal nerve, which may have an independent -igin from the sacral plexus, passes inwards across the ischio-rectal issa to the region of the anus, and is distributed to the external >hincter muscle and the skin around the anus.

The perineal nerve is a large branch which passes forwards in the udendal canal, being the lowest of its contents. It ultimately divides ito superficial and deep branches.

The superficial branches are two in number, and are called the iteral and medial scrotal nerves. Both nerves, having emerged from le pudendal canal into the ischio-rectal fossa, pass forwards and ierce the base of the inferior layer of the perineal membrane. They ien run forwards with the superficial perineal artery under cover of re deep layer of superficial perineal fascia, and on approaching tie back of the scrotum they divide into long slender cutaneous ranches.

In the anterior division of the perineum the two superficial perineal erves communicate freely, and are accompanied by the long perineal erve (of Soemmering), which is a branch of the posterior cutaneous erve of the thigh. This nerve, having pierced the fascia lata about inch in front of the ischial tuberosity, passes inwards over the ischioubic ramus and through the deep layer of superficial perineal fascia, t then runs forwards and inwards beneath this fascia to the scrotum, ^ing on the ischio-cavernosus muscle, close to the ischio-pubic ramus, upplying the skin of the scrotum, and communicating with the ateral posterior scrotal nerve.

The deep branch of the perineal nerve furnishes offsets which, with >ne exception, are muscular in their distribution, and supply the interior part of the external sphincter, the anterior part of the levator mi, the superficial transverse perineal, the ischio-cavernosus, and the mlbo-spongiosus. The non-muscular branch, called the nerve of the )ulb, pierces the bulbo-spongiosus muscle and the wall of the bulb, 0 be distributed to the erectile tissue of the corpus spongiosum and he mucous membrane of the spongy part of the urethra.

The dorsal nerve of the penis is at first contained in the pudendal

anal, where it lies above the internal pudendal vessels. Having emerged from that canal, it pierces the superior layer of the perineal nembrane near its base. It then passes forwards and upwards, with the fourth part of the internal pudendal artery, between the two ayers of the perineal membrane, in which situation it lies on the outer fide of the internal pudendal vessels, and close to the ischio-pubic ramus, being embedded in the sphincter urethrae muscle. Its subsequent course is similar to that of the dorsal artery of the penis, which it accompanies. On the dorsum of the penis, where it lies lateral to the dorsal artery, it is continued as far as the glans, where it ends in branches for the glans and prepuce. As the nerve lies between the two layers of the perineal membrane, it gives branches to the sphincter urethrae muscle, and it also furnishes the nerve of the corpus cavernosum. This latter nerve, having pierced the sphincter urethrae and inferior layer of the perineal membrane, enters the crus and is continue forwards in the corpus cavernosum to supply its erectile tissue. A the nerve passes along the dorsum of the penis, it supplies numerou cutaneous branches.

Structures divided in Left Lateral Lithotomy. —The structures divided in thi operation are as follows: (1) the skin; (2) the subcutaneous layer of the super ficial fascia; (3) the deep layer of the superficial fascia or the fascia of Colies (4) the transverse perineal vessels; (5) the superficial transverse perineal muscle (6) the inferior hsemorrhoidal nerve and the inferior rectal vessels; (7) the bass part of the inferior layer of the perineal membrane; (8) the sphincter urethr; muscle and the plexus of veins embedded in it; (9) the membranous part of th urethra; (10) the superior layer of the perineal membrane; (11) the anterior fibre of the levator ani muscle; (12) a portion of the left lateral lobe of the prostat gland, with its capsule and some of the veins of the prostatic plexus; and (13) th prostatic urethra.

Structures to be avoided. —The structures to be avoided are as follows: (1) th rectum; (2) the internal pudendal vessels as they lie in the pudendal canal (3) the artery of the bulb; and (4) the common ejaculatory duct.


Female Perineum

The female perineum is divided into three regions—uro-genita perineum proper (as defined by the obstetrician), and anal. The uro genital division is situated at the anterior part, and comprises th pudendum and uro-genital cleft. The perineum proper is situate< between the posterior part of the uro-genital cleft and the anus* Th' anal division is situated as in the male.

Uro-genital Division

The uro-genital division contains the external uro-genital organs These collectively constitute the pudendum muliebre or vulva, am comprise the following parts: the mons pubis; labia majora; labi; minora; clitoris; vestibule; external urethral orifice; vaginal orifice including the hymen of the carunculse hymenales; frsenulum pudendi vestibular fossa; bulbs of the vestibule; and the greater vestibula glands.

The mons pubis (Veneris) is an eminence situated in front of anc above the upper part of the symphysis pubis. It is produced by c collection of adipose tissue, the skin over which is more or less freei} provided with hair after the age of puberty.

The labia majora are two thick, round folds of skin, which ar( directed from before backwards, with a slight inclination downwards The length of each is about 3 inches. Posteriorly they become thin and fading away lose themselves in the anterior part of the perineun proper, about 1 inch in front of the anus. The junction to which the name of the posterior commissure has been given is of rare occurrence Anteriorly they retain their thick, round character, and become con tinuous with the mons pubis, forming the so-called anterior commissure. Each labium majus has two surfaces, outer and inner. Tht


THE ABDOMEN


693


tin covering the outer convex surface is somewhat dark in colour, ke that of the scrotum, and contains numerous sebaceous glands of trge size. It is also more or less freely provided with hair after the ge of puberty, except towards the posterior part. The inner flat jrface forms the lateral boundary of the uro-genital cleft, and touches lat of the opposite side. The skin covering this surface is smooth nd free from hair, and presents the openings of the ducts of sebaceous lands. Each labium majus contains adipose and areolar tissues, and small amount of dartos tissue. The ligamentum teres uteri of each ide loses itself in this labium, and superficial and deep fasciae from tie lower part of the anterior abdominal wall also enter it. The ssure between these labia is called the uro-genital cleft (rima pudendi), nd is almost horizontal, its direction being antero-posterior. The


Mons Pubis—«=.


M\u

Anterior Commissure

jf


Labium Majus


- Labium Minus ' External Urethral Orifice


-External Orifice of Vagina


Vestibular Fossa Frenulum Labiorum Posterior Commissure


Fig. 411.—The External Genital Organs of the Female.

lood-supply and nerve-supply of the labia majora correspond with hose of the scrotum.

The lymphatics arise from a rich network in each labium majus, these networks being connected with each other across the median line. The efferent essels pass to the superficial inguinal glands. Some vessels are said to cross tie median line and terminate in the glands of the opposite side.

The labia minora (nymphse) are two narrow, more or less pendulous olds of integument, which are situated in the uro-genital space, each png internal to the corresponding labium majus. They become coninuous with each other anteriorly, in the region of the clitoris, a hort distance from the anterior commissure, in a manner to be presently lescribed. From this point they diverge as they pass backwards, and 0 form the lateral boundaries of the space called the vestibule. Each






694


A MANUAL OF ANATOMY


terminates posteriorly by blending with the inner surface of the com sponding labium majus, or in some cases by becoming continuous wit' its fellow, forming the frenulum labiorum. Each labium minus ha two surfaces, outer and inner, and two borders, superior and inferioi The outer surface is in contact with the inner surface of the labiur majus of the same side, and the inner surface touches that of the oppc site labium minus. Each surface is covered by a modified form of skir that on the inner surface being extremely delicate, and being some what like mucous membrane. The true mucous membrane, howevei only commences at the inner side of the base or superior attache border of the labium minus. The labia minora, previous to thei union anteriorly, divide each into two laminae. The upper and large lamina passes over the clitoris, and becomes continuous with that c the opposite side, thus forming a cap for that organ, called the prepuc of clitoris. The lower and smaller lamina passes below the clitoris where it also becomes continuous with that of the opposite side. A the line of junction of the two lower laminae they are attached to th under surface of the clitoris, thus forming the frenulum of clitoris The labia minora are destitute of both hair and fat, but they contai sebaceous glands. They sometimes attain a large degree of develop ment, in which cases they project through the uro-genital cleft. I: some African women they become so much developed as to reach dow: to the knees. When this occurs they form what has been called th Hottentot apron. The labia minora are homologous with the floo of the spongy part of the urethra, the skin of the penis, and the prepuc in the male.

Development of the Labia. —The opening of the uro-genital sinus extend ventrally on to the base of the genital eminence. The opening is bordered by th labio-scrotal folds, which also extend to the eminence. These folds, enlargin slightly, become the labia minora ; the labia minora thus extend to the lowe aspect of the eminence, which becomes the clitoris. The labia majora are modi fications of the genital swellings, which in the male become the scrotum. Th fusion of the labio-scrotal folds in the male converts what is, in the female, th vestibule of the vulva into the spongy urethra, and the laterally placed genitc swellings, meeting over the closed folds, constitute the scrotum.

The clitoris is situated in the uro-genital cleft a little behind th anterior commissure, and is composed of two corpora cavernosa an< a glans. Each corpus cavernosum occupies, by means of a crus, \ groove which winds spirally round the inner border of the ischio-pubi ramus, the crus being covered by the ischio-cavernosus or erecto clitoridis muscle, and lying superficial to the inferior layer of th perineal membrane. The two corpora cavernosa unite by their inne flattened surfaces, and so form the body of the clitoris, which is abou ij inches long. The septum, which is interposed at the line of junctioi of the corpora cavernosa, is interrupted by vertical clefts, and is calle( the commissure of bulb (septum pectiniforme). The dorsal surface o the clitoris at its upper end is attached to the front of the symphysi pubis by a small suspensory ligament, and the distal end of the orgai


THE ABDOMEN


695


capped by an imperforate glans. The glans, which caps the corpora avernosa, is composed of erectile tissue, and is extremely sensitive, t is provided with a prepuce and a frenulum, both of which are continous with the labia minora. The organ is composed of erectile tissue.

The clitoris is the homologue of the penis, from which it differs in he following respects: (1) the only part of a corpus spongiosum which

possesses is the glans (the part of the corpus spongiosum of the male diich lies between the bulb and the glans penis being represented in he female by the pars intermedia of the bulb of the vestibule; (2) it .oes not contain the female urethra; and (3) its component parts are auch smaller than those of the penis. In reality the clitoris is a liminutive penis, minus the corpus spongiosum and the urethra. It is leveloped from the genital eminence.

Lymphatics. —The lymphatics of the prepuce of the clitoris accompany those if the labia majora, and pass to the superficial inguinal glands.

The lymphatics of the glans clitoridis run on the dorsum of the clitoris towards he front of the symphysis pubis, where they form a network. The vessels vhich emerge from either side of this network have the following destinations: 1) Some pass to the deep inguinal glands, and thence through the femoral canal o the internal chain of the external iliac glands ; and (2) others traverse the nguinal canal and terminate in the lowest gland of the outer chain of the external

liac glands. . .

The lymphatics of the corpora cavernosa pass to the internal iliac glands on

iither side.

The vestibule is the space which is enclosed by the labia minora, and s so called because it is the ‘ porch ’ of the vagina. It is triangular, the ipex, which is in front, being formed by the glans clitoridis, the lateral Doundaries by the labia minora, and the base by the frenulum labiorum. It is 2 inches or more in length, and presents a smooth surface covered by a mucous membrane of stratified squamous epithelium. Half-way ilong the vestibule in the middle line, and immediately in front of the external orifice of the vagina, is a slight prominence with somewhat irregular margins. Upon this prominence the external urethral orifice is situated at a point 1 inch behind the clitoris. The irregular prominence serves as a guide to this opening.

The vestibule represents the remains of the uro-genital sinus.

The external orifice of the vagina is an antero-posterior cleft, having an elliptical shape when partially dilated. The portion of the vagina close above it is the narrowest part of the passage. For the description of the vagina, see Female Pelvis.

The hymen in its normal condition is a thin semilunar fold of mucous membrane which is stretched across the posterior third, or half, of the external orifice of the vagina. Its concave border, which is free, is directed forwards and upwards. Sometimes the hymen completely surrounds the circumference of the orifice, an aperture being left in its centre. In other cases it stretches over the entire opening, but is perforated by apertures which give it a cribriform appearance. In rare cases it is an entire membrane, completely shutting off the vaginal canal from the uro-genital cleft, and it is then spoken of as an


6g6


A MANUAL OF ANATOMY


imperforate hymen. In some cases, even in the virgin, it is entire absent.

The hymen begins to appear about the fifth month of intra-uterine life a fold of mucous membrane at the point where the vagina opens into the ui genital sinus.

The carunculae hymenales (myrtiformes) are small elevations whii represent the remains of the hymen after its rupture. Though calli carunculce (fleshy), they are really mucous excrescences.

The frenulum labiorum (fourchette) is a crescentic fold formed 1 the union posteriorly of the two labia minora. It is not always reco nizable, and is best marked in early life.


Right Greater Vestibular Gland and its Duct

Fig. 412.—Dissection showing the Bulbs of Vestibule and Greater Vestibular Glands (modified from Kobelt).

The cross on either side of the vaginal orifice shows the position of the opening of the duct of the greater vestibular gland.

The vestibular fossa (navicularis) is a small depression which lie between the hymen and the frenulum labiorum.

The bulbs of vestibule (Fig. 412) are two ovoid masses of erectil tissue 1 inch in length, which are situated on either side of the vestibul beneath the mucous membrane. Each bulb is covered by a delicat fibrous capsule derived from the inferior layer of the perineal membran( superficial to which the bulb of either side lies. The outer surface i convex, and is covered by one half of the bulbo-spongiosus muscle the inner surface is slightly concave, and is covered by the vagina mucous membrane. Posteriorly the bulbs diverge, and anteriorly having become narrow, they pass upwards and forwards, and ultimate! meet in the middle line, where they are attached to the inferior layer 0 the perineal membrane. In front of the bulbs there is a plexus of vein which is continuous behind with their erectile tissue, and in front witl







THE ABDOMEN


697


that of the glans clitoridis. This plexus of veins is known as the pars intermedia. It receives veins from the labia minora, and its blood is conveyed into the vaginal plexus.

The bulbs of the vestibule together represent the bulb of the male urethra, which latter presents on its under surface a faint groove in the middle line, indicating a bilateral origin. The pars intermedia is regarded as representing that part of the male corpus spongiosum which extends from the bulb to the glans penis.

The greater vestibular glands (Bartholin’s glands) belong to the class of racemose or acino-tubular glands. They are two in number, right and left, and each resembles a small bean. They lie on either side of the external orifice of the vagina, immediately behind the posterior extremities of the bulbs of the vestibule, into which certain of their lobules may project. The duct of each gland is about £ inch long, and opens in the angle between the attached border of the labium minus


Fig. 413.—The External Genital Organs at the End of the Indifferent Stage seen from the Front and from the Side.

GF, labio-scrotal fold; GS, genital swelling; GT, genital tubercle.

and the hymen or its remains a little in front of the vestibular fossa. The orifices of these ducts are usually plainly visible to the naked eye.

These glands are homologous with the bulbo-urethral glands, and their structure is similar.

The greater vestibular glands are developed from the lining epithelium of the uro-genital sinus.

The external uro-genital organs of the female have received the name of vulva. As this word, however, literally signifies a ‘ covering/ it is strictly applicable only to the labia majora, which by their approximation form a covering for the uro-genital cleft and its contents.

Development of the External Genital Organs.

In the early stages no sexual differences are apparent in the development of the external genital organs. The chief parts concerned are (1) the genital eminence, (2) the genital groove, (3) the labio-scrotal folds, and (4) the genital swellings.


6 g8


A MANUAL OF ANATOMY


Female External Organs. —The surface-depression corresponding the cloacal membrane, which bounds the cloaca postero-inferior] is known as the cloacal depression. As the cloaca becomes divide into two compartments—dorsal or intestinal, and ventral or ur genital—by the cloacal or uro-rectal septum, the cloacal membra; is also divided into two parts—dorsal or anal, and ventral or ur genital. Moreover, the superficial cloacal depression is likewi divided into two parts—dorsal, which is called the anal depressn or proctodceum ; and ventral, which is known as the uro-genital a pression, and is somewhat cleft-like. When the uro-genital portic of the cloacal membrane ruptures, the uro-genital sinus or canal cor municates with the exterior by means of the uro-genital opening < cleft.

The formation of the subdivisions of the cloaca is described ar figured on p. 98, and the slit-like opening of the uro-genital sim


Male. Female.

RapM of Penis^ Gians Penis Gians Clitoridis Genital Swelling


Fig. 414.—Development of the External Genital Organs.

is seen to extend forward on the lower aspect of the growing genita tubercle.

The female external genital organs are developed around the uro genital opening. At the cephalic part of the primitive vestibule ; small tubercle, called the genital eminence or tubercle, makes it appearance in the median line. On the lower, or vestibular, surfac< of this eminence a furrow, called the genital groove, marks the forwarc prolongation of the uro-genital opening. The lips of this groove which are laterally disposed, are called the labio-scrotal folds. Or either side of the genital eminence, external to the corresponding genita fold, a low ridge makes its appearance. These ridges are known as the genital swellings. They are continuous with each other on the ventral aspect of the genital eminence, and they extend dorsalwards ; lying on either side of the vestibule, and finally meeting behind in the perineum.

The genital eminence undergoes lengthening, and gives rise to the plitons, The terminal extremity of the eminence becomes enlarged,


THE ABDOMEN 699

md forms the glans clitoridis, whilst the remainder gives rise to the zorpora cavernosa clitoridis.

The labio-scrotal folds, which in the male fuse, enclosing the spongy part of the urethra, and forming the corpus spongiosum penis, remain separate in the female, and form the labia minora. The genital swellings, which in the male come together and form the scrotum, remain separate in the female, and give rise to the labia majora. The ventral portions of the external swellings, which are continuous with each Dther on the ventral aspect of the genital eminence, form the mons pubis.

The hymen appears as a semilunar fold of mucous membrane, extending as a rule over the dorsal part of the external orifice of the vagina.


Fig. 415.— Figures of Male and Female Organs at the End of

the Second Month.


The labio-scrotal fold (GF) is being carried forward on the base of the penile prominence in the male. The clitoris is very long in the female, but the folds and the genital swellings (GS) are less prominent.

The greater vestibular glands are developed laterally as evaginations of the epithelial lining of the caudal part of the uro-genital sinus, which part, when expanded, forms the vestibule.

The bulbs of the vestibule and the pars intermedia are developed as masses of erectile tissue close to the labia minora and clitoris.

Male External Organs. —The genital tubercle undergoes lengthening, although this is not so marked a feature in the male at first as it is in the female. The lengthening, occurring later, appears to be of a different nature than in the female, for the parts of the labio-scrotal folds which are related to the tubercle seem to be drawn out with it in its growth, and help to form the shaft of the penis. The eminence forms the glans , and the corpora cavernosa are developed partly from the tubercle, but mainly from the genital folds. With the elongation






700


A MANUAL OF ANATOMY


and general growth the groove on the lower surface is drawn out arj deepened. The labio-scrotal folds forming the lips of the groove, whic remain open in the female, close over it in the male, so that the groo\ is converted into the spongy urethra.

It is difficult to decide whether the lips fuse from behind forward, or the hinder junction is simply carried forward with the folds on the lengthening peni The presence of a raphe on the scrotal aspect of the penis seems to suggest the fusion occurs.

The opening of the uro-genital sinus on the surface is thus carrie forward more and more, reaching the lower surface of the penil prominence (Fig. 416). Continuation of the closing process shuts 0: the spongy urethra from the surface, but about the time this take place the urethra in the glans is formed by hollowing out of the ectc dermal plate which occupied the (potential) groove on the eminence


Fig. 416. —Male External Organs during the Third and Early

Part of Fourth Month.

the canal formed in this way becomes continuous with the spongy urethra.

The spongy part of the urethra extends as far as the uro-genital sinus, from the lower part of which the prostatic and membranous parts of the canal are developed.

In rare cases the genital folds fail to unite over some portion of the genital groove. In such cases the spongy urethra opens externally on the under, or scrotal, aspect of the penis, and the condition is known as hypospadias.

The labio-scrotal folds, which enclose the spongy part of the urethra, acquire erectile tissue and constitute the corpus spongiosum penis. The genital eminence, having lengthened considerably, and having acquired erectile tissue, gives rise to parts of the corpora cavernosa penis, whilst its terminal enlargement forms the glans penis.

The genital swellings, which in the female remain separate and form the labia majora,, unite in the male and give rise to the scrotum. The line of fusion is indicated in adult life by the scrotal raphe.






THE ABDOMEN


701


It is to be noted that, whilst the prostatic and membranous portions

the male urethra are developed from the lower part of the urolital sinus, and are therefore non-penile , the spongy portion of the aal is developed from (1) the genital groove on the lower surface of the aital eminence, and (2) the internal genital folds. The spongy part the urethra is therefore penile.

The bulb of the corpus spongiosum penis represents the bulbs of ! vestibule of the female, and the portion of the corpus spongiosum nis between the bulb and the glans penis represents the pars inter'dia of the body of the clitoris in the female.

Perineum Proper.

The perineum proper is the region which lies between the anus and e vestibule. It is in this division that the perineal body is situated.

Perineal Body. —It is situated between the anus and the vaginal [fice. It is triangular in outline, and is about ib inches in breadth.


Fig. 417. —Female Bony Pelvis from Below.

ST =sacro-tuberous ligament; IP =ischio-pubic ramus.

is bounded in front by the posterior wall of the vagina, behind by the iterior wall of the anal canal, and inferiorly by the skin. The perineal >dy is produced by a thickening of connective tissue, with a free Imixture of elastic tissue and a few muscular fibres derived from the

ternal sphincter, levatores ani, and bulbo-spongiosus muscles. It rves as a support to the posterior wall of the vagina. During parturi3 n it becomes greatly stretched, but its elastic tissue usually guards against rupture.

Perineal Membrane. —The perineal membrane resembles that of te male in being composed of two layers, inferior and superior.

The inferior layer, on account of the greater width of the pubic xh in the female, is broader than in the male, though it is more ^definite on account of its being pierced by the vagina. It is attached t either side to the posterior margin of the inner border of the ischioubic ramus, and anteriorly blends with the transverse perineal ligament. In the middle line, where it is pierced by the vagina, it blends ith the wall of that canal. Its base is joined by a somewhat indefinite



702


A MANUAL OF ANATOMY


layer of fascia representing the deep layer of superficial perineal fasc in the male, and by the superior layer. The openings in the inferi layer are similar to those in the male, with this exception, that t ducts of the greater vestibular glands do not pierce it as the ducts the bulbo-urethral glands do in the male, the greater vestibular glan being situated superficial to this layer. The urethral opening is situab i inch below the symphysis pubis. The opening for the vagina, whi< is of large size, lies below the urethral orifice, from which it is separati by a few fibres. The openings for the arteries of the bulbs of £ vestibule are situated one on either side of the vaginal opening. T openings for the deep artery of clitoris, for the dorsal artery and ner of the clitoris, and for the superficial perineal vessels and nerves, a situated as in the male.

It is to be noted that the dorsal vein of the clitoris, like the corr sponding vessel in the male, passes between the inferior and transver perineal ligaments.

The superior layer is similar to the corresponding layer in the mal and presents openings for the urethra, vagina, and internal pudend vessels and pudendal nerves of each side.

Anal Division.

The chief characters of the anal division in the female are as follow the aperture of the anus is somewhat nearer the coccyx than in tl male, the distance between the ischial tuberosities is greater than the male, and the ischio-rectal fossae are wider and shallower than the male.

Muscles. —The muscles of the female perineum, as compared wil those of the male, present certain differences.

Levatores Ani. —The anterior fibres of these muscles embrace tl vagina instead of the prostate gland, as in the male.

Ischio-cavernosus (Erector Clitoridis). —This muscle replaces tl ischio-cavernosus of the penis, and is of small size.

Bulbo-spongiosus (Sphincter Vaginae). —This muscle arises from tl perineal body, where it meets the external sphincter and superfici; transverse perineal muscles. It then passes forwards and divid< into two symmetrical parts which surround the vaginal orifice an vestibule, each part closely embracing the outer surface of the corn sponding bulb of vestibule. Anteriorly the two parts become vei narrow, and each is inserted into the fibrous sheath of the corpi spongiosum. A few fibres are here detached to be inserted into tendinous expansion on the dorsum of the clitoris covering the dors; vein, which vessel would be thereby compressed when the muscle in action. Some of the inner fibres of the bulbo-spongiosus are inserte into the mucous membrane of the vestibule.

Sphincter Urethrae. —This muscle, as in the male, lies between tb two layers of the perineal membrane. It is attached on either sid to the inner margin of the ischio-pubic ramus, and in the middle lin


THE ABDOMEN


7°3


is almost completely divided into two parts by the vagina. The nterior part passes transversely across the pubic arch in front of the rethra, whilst the posterior and larger part passes inwards, partly ransversely and partly obliquely, to blend with the vaginal wall.

The external sphincter and superficial transverse perineal muscles re similar to those in the male.

Internal Pudendal Artery. —This vessel is of smaller size than in the lale, but it takes a similar course. The difference, therefore, in the wo sexes affects chiefly the branches of the artery.

The superficial perineal artery is larger than in the male, and is istributed to the labium majus.

The artery of the bulb is of comparatively small size, and is disributed to the bulb of the vestibule.


Ischio-cav., on Crus. Cavernosus

Bulbo. Sp. on Bulb Perineal Membrane Sup. Trans. Perinei


Fig. 418. —Ischio-rectal Fossa and Muscles of Female Perineum.

The deep artery of the clitoris, having pierced the inferior layer of fe perineal membrane, enters the crus clitoridis, and is then continued nwards in the centre of the corpus cavernosum.

The dorsal artery of the clitoris, like the preceding, is comparatively mall in size. Having pierced the inferior layer of the perineal memrane, it passes between the crura clitoridis, and also between the wo layers of the suspensory ligament of the clitoris. It is then coninued along the dorsum of that organ as far as the glans, having the orsal vein of the clitoris on its inner side and the dorsal nerve of the litoris on its outer side. On reaching the glans it divides into branches Dr the supply of the glans and its prepuce. As it passes along the orsum of the clitoris it gives off several branches, which enter the orpus cavernosum by piercing its fibrous sheath.

The veins of the female perineum are so similar to those in the male s not to require any special description. An exception, however, has










7 o 4


A MANUAL OF ANATOMY


to be made in the case of the dorsal vein of the clitoris. This vein i formed by branches which return the blood from the glans and pre puce, and also to a certain extent from the corpora cavernosa. I passes backwards in the groove between the corpora cavernosa, when it has on either side of it the dorsal artery, and lateral to this the dorsa nerve, of the clitoris. In this part of its course it receives tributarie from the corpora cavernosa. On reaching the root of the organ i passes between the two layers of the suspensory ligament of the clitoris and then between the inferior and transverse perineal ligaments, anc so enters the pelvic cavity, where it terminates in the plexus of vein: at the neck of the bladder.

Lymphatics. —The lymphatics of the vulva, including those of the prepuce of clitoris, terminate in the superficial inguinal glands , whicf lie immediately below the inguinal ligament. The lymphatics of the glans clitoridis, like those of the glans penis, pass to the deep inguinal and external iliac glands. The lymphatics of the vagina and urethra run with the vaginal vessels, those of the bulb and corpora cavernosa clitoridis with the internal pudendal vessels, both sets of lymphatics terminating in the internal iliac glands.

The pudendal nerve and its branches are similar to those in the male, the superficial perineal nerves being distributed to the labia majora.


ABDOMINAL WALL.

Landmarks. —The position of the linea alba is indicated by the mid-abdominal groove, which extends from the xiphoid process of the sternum to the umbilicus, and by the mid-abdominal line, which extends from the umbilicus to the upper part of the symphysis pubis. After removal of the skin the linea alba presents a dense white appearance, and is slightly depressed below the level of the adjacent surfaces. It is produced by the decussation of the aponeuroses of the abdominal muscles of opposite sides, except the recti, and is divided into two parts, supra-umbilical and infra-umbilical. The supraumbilical part is about J inch broad, the recti being here separated to that extent. The infra-umbilical part is only about J inch wide on account of the approximation of the recti in this situation. Over the whole extent of its posterior or abdominal surface it is invested by the parietal peritoneum, unless in cases of abnormal distension of the bladder, when the peritoneum is stripped from the lower part to an extent corresponding with the height to which the distended bladder ascends. The anterior abdominal wall is thinner and less vascular along the linea alba than at any other part. This line is therefore selected for such operations as suprapubic lithotomy, tapping a distended bladder above the symphysis pubis, and ovariotomy.

The structures which are divided in opening the abdominal cavity along the linea alba are as follows: the skin, the decussating fibres of the aponeuroses of opposite sides, fascia transversalis, subperitoneal areolar tissue, and parietal peritoneum. There are no bloodvessels of any importance in this situation.


THE ABDOMEN


7°5


The posterior aspect of the linea alba has important visceral rela;ions. The left lobe of the liver lies behind it for about 2 inches below

he xiphoid process of the sternum. The relation of the stomach to it s variable. When the viscus is moderately distended it lies behind the inea alba below the margin of the liver. In the empty condition, lowever, it recedes from the linea alba, and this gives rise superficially

o the epigastric depression, or scrobiculus cordis (‘ small trench of the ieart ’). The transverse colon, covered by the greater omentum, as t crosses from right to left, usually lies behind the linea alba just above

he umbilicus. The coils of the jejunum and ileum, also covered by the greater omentum, lie behind it below the umbilicus.

In young persons the upper part of the bladder, being extra-pelvic, ies behind the lowest part of the linea alba. In adults the upper part }f that viscus, when abnormally distended, also lies behind the lowest Dart of this line.

The umbilicus takes the form of a cicatricial depression which is situated in the linea alba at the junction of the upper three-fifths and ower two-fifths. As seen from the front it is irregularly circular, the skin being more or less puckered according to the state of distension Df the abdomen. When viewed from the back it is smaller in size, and its long measurement lies transversely. Besides cicatricial tissue and [at, the lower part of it contains the upper ends of the urachus and Dbliterated hypogastric arteries, whilst the upper part is occupied by part of the obliterated umbilical vein. The upper part is weaker than the lower. The umbilicus is on the same horizontal plane as the disc between the bodies of the third and fourth lumbar vertebrae.

In embryonic life there is an opening in the middle line of the ventral abdominal wall, through which the intra-embryonic and extraembryonic portions of the gut are continuous with one another. The body-stalk or umbilical cord is attached to the caudal margin of this opening, extending for a little distance along its sides also, especially on the left side. When the intestines enter the abdomen, in the tenth week, the edges of the opening come together, joining medially in a few days, but the umbilical cord, of course, retains its attachment. After birth, when the foetal end of the cord sloughs off, the area of its previous attachment forms a scar, which is the umbilicus. If the original opening were to persist, it would be in front (above) this scar, though close to it, and on the right-hand side of the umbilical end of the ligamentum teres of the liver, the remnant of the left umbilical vein.

The linese semilunares (Fig. 419) coincide with the outer borders of the recti abdominis. The position of each is indicated by a line drawn from the lowest part of the eighth costal cartilage to the pubic tubercle. This line is curved, with the convexity outwards, and at the level of the umbilicus it is about 3 inches from it. Over the upper three-fourths of the rectus abdominis it indicates the splitting of the aponeurosis of the internal oblique into two laminae, which encase that extent of the muscle in a sheath. Over the lower fourth it indicates where the aponeurosis of the external oblique and part of the aponeurosis

45


706


A MANUAL OF ANATOMY


of the internal oblique separate from the remainder of the aponeuros of the internal oblique and the aponeurosis of the transversus, tl former aponeuroses passing forward in front of the rectus, while ti latter pass with a curved course downward along the outer edge the rectus.

The substance of the rectus abdominis is traversed by three hoi zontal tendinous intersections (linea transverse) which cross the recti in the following situations: one at the level of the umbilicus, one ;


the level of the lower margin of the thorax, and one about miawa; between these two. The positions of the intersections are indicate* by three faint grooves. The anterior wall of the sheath of the rectu is closely bound down to the tendinous intersections, and so each muscf above the umbilicus is mapped out into quadrangular areas, and th< interior of the sheath, anterior to the muscle, is also divided int< distinct compartments. An abscess may form in one or other of thes< compartments, or there may be a spasmodic contraction of one o other of these quadrangular areas of the muscle, a condition in eacl







THE ABDOMEN


707


case which would necessarily have a circumscribed limit, and might lead to error in diagnosis.

The spino-umbilical lines are two in number, right and left, and each extends from the anterior superior iliac spine to the umbilicus.

The anterior superior spine of the ilium is situated at the anterior extremity of the iliac crest, and, being very superficial, can be readily felt. It is on the same level with that of the opposite side, and therefore a line connecting the two should be quite horizontal. The plane of this interspinous line is rather lower than the promontory of the sacrum. The anterior superior iliac spine is one of the points from which the measurement of the lower limb is taken, the other point being the medial malleolus. This spine is also a good ready guide to the position of the greater trochanter, which is situated about 4 inches below it, and about 4J inches behind a line passing vertically through it.

The pubic tubercle is situated at the lower and inner part of the anterior abdominal wall, about ij inches outside the upper part of the symphysis pubis. It is sometimes a sharp-pointed process, and then can readily be felt beneath the skin. In most persons, however, it takes the form of a more or less indistinct tubercle, and cannot readily be made out. In such cases the scrotal integument may be invaginated with the finger, and so the adipose tissue raised from over the spine. If it cannot be felt in this way, the thigh should be well abducted to render prominent the adductor longus muscle, the tendon of origin of which will serve as a guide to the spine, which lies above and to the outer side of it. The pubic tubercle is the guide to the superficial inguinal ring, the femoral ring, and the saphenous opening. The superficial inguinal ring is situated immediately above the pubic tubercle. In exploring the ring, the best way to proceed is to invaginate the scrotal integument, and carry the examining finger up the inner side of the spermatic cord, when the ring will be reached. In normal circumstances it should admit the point of the little finger. In making this examination the spermatic cord is readily felt, and the vas deferens can be distinguished as a firm cord-like structure lying posteriorly, and easily separable from the other constituents of the cord. In the female the ligamentum teres of the uterus takes the place of the spermatic cord, but, being a very ill-defined structure, it usually escapes detection. The femoral ring is situated fully 1 inch lateral to the pubic tubercle in a line drawn transversely outwards from that spine across the front of the thigh. The saphenous opening is situated below, and lateral to, the pubic tubercle.

The pubic crest extends transversely inwards for about ij inches from the pubic tubercle, and terminates in the pubic angle, which surmounts the medial surface of the pubic body, and is usually a rudimentary tubercle. The crest may be felt with the finger as the superficial inguinal ring, of which it forms the base, is being explored.

The inguinal ligament can be felt as a tense band, especially when the thigh is extended, abducted, and rotated outwards, passing between the anterior superior iliac spine and the pubic tubercle.


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A MANUAL OF ANATOMY


The deep inguinal ring is situated inch above the mid-point o the inguinal ligament.

The inguinal canal extends for i-| inches obliquely downwards forwards, and inwards from the deep to the superficial inguinal ring and is situated immediately above the inner half of the inguina ligament.

Topography of Arteries, Triangles, and Iliac Fossae. —The bifur cation of the aorta into right and left common iliac arteries usualh takes place opposite the centre of the body of the fourth lumba vertebra, a finger’s breadth to the left of the middle line. The positioi of the bifurcation is indicated in one of two ways: (i) a point J incl below and to the left of the umbilicus; (2) a more definite guide is ; point in the line which connects the highest parts of the iliac crest: a finger’s breadth to the left of where it intersects the linea alba.

The common and external iliac arteries are indicated by a line drawn from a point midway between the anterior superior iliac spine and the symphysis pubis to the point corresponding to the bifurcatior of the aorta. This line should be slightly curved, with the convexity directed outwards. Its upper 2 inches indicate the course of the common iliac artery, and the remainder represents the external iliac.

The inferior epigastric artery, in its first or oblique part, is indicated by a line drawn from the inner border of the deep inguinal ring to the outer border of the rectus abdominis at a point midway between the upper border of the symphysis pubis and the umbilicus. The subsequent course of the vessel is represented by a line corresponding to the centre of the rectus abdominis, and reaching to a point about 2 inches above the umbilicus. This latter line is about ij inches distant from the linea alba.

I he inguinal triangle (Hesselbach’s) is situated on the inner side of the first or oblique part of the inferior epigastric artery, and above the inner half of the inguinal ligament.

The lumbar triangle (of Petit) is situated immediately above the centre of the iliac crest. In this region a lumbar hernia may protrude, and a lumbar abscess may here come to the surface.

The right iliac fossa contains the terminal part of the ileum, the caecum, the vermiform appendix, and beginning of the ascending colon.

I he left iliac fossa contains the iliac part of the descending colon.

McBurney’s point is situated in the right spino-umbilical line between _i J and 2 inches from the anterior superior iliac spine. According to McBurney, it corresponds very accurately in the living subject to the base of the vermiform appendix. Practically it coincides with the centre of the right iliac fossa. The point is now regarded as indicating approximately the situation of the ileo-colic valve, and not the base of the vermiform appendix. The guide to the base or opening of the

appendix is a point on an average rather more than 1 inch below the ileo-colic valve.


THE ABDOMEN


7 ° 9


Anterior Abdominal Fasciae. —The superficial fascia of the anterior vail of the abdomen, from the inguinal ligament to a line drawn transversely from the anterior superior iliac spine to the linea alba, resembles he superficial fascia of the uro-genital division of the perineum in )eing divisible into two layers. The layer immediately beneath the kin is called the fatty superficial layer, and the other layer is called he deeper membranous layer.

The fatty superficial layer (fascia of Camper) is composed of areolar issue containing adipose tissue in its meshes. When traced upwards, t blends with the deep layer above the level of the line connecting the .nterior superior iliac spine with the linea alba. When followed inwards, it is continuous with the corresponding layer of the opposite ide. In a downward direction it is freely continuous over the inguinal igament with the superficial layer of the superficial fascia of the ront of the thigh. When traced downwards and inwards, it passes long the spermatic cord into the scrotal wall and over the penis, in vhich situations, more especially the former, it contains involuntary nuscular fibres, which replace its adipose tissue, and so, with the deep ayer which it here joins, it forms the dartos muscle. In the female, he fatty superficial fascia passes along the ligamentum teres of the items into the labium majus.

The deeper membranous layer (fascia of Scarpa) is a strong membrane which contains yellow elastic tissue. It is separated from the uperficial layer by the superficial epigastric vessels, and in the region f the inguinal ligament by the inguinal glands. Its deep aspect is aosely connected by areolar tissue to the subjacent aponeurosis of he external oblique muscle. Superiorly, above the line connecting he anterior superior iliac spine with the linea alba, it blends with uperficial layer. At the middle line it is firmly bound down by fibrous •ands to the linea alba. Interiorly it blends medially with the inguinal gament, but laterally it passes over that ligament for a distance of n inch or so, and then becomes incorporated with the fascia lata of he thigh. When traced downwards and inwards, it passes along the permatic cord into the scrotal wall and over the penis. In the former ituation it forms, along with the superficial layer, the dartos muscle. n the female, the deeper layer passes along the ligamentum teres of he uterus into the labium majus.

The superficial layer is continuous through the dartos muscle with he superficial layer of the superficial fascia of the uro-genital division f the perineum, and the deeper layer is similarly continuous with the eep layer of the superficial fascia. In the middle line the deeper layer 5 continued down in the form of a collection of fibres which, separating ito two bundles, pass on either side of the penis to blend with the heath. To these fibres the term superficial suspensory ligament of he penis has been applied.

The disposition of the deeper membranous layer at the line of the rom explains why, in cases of extravasation of urine beneath the deep l yer of superficial perineal fascia, the urine, when it reaches the


A MANUAL OF ANATOMY


710

anterior abdominal wall, does not pass downwards to the front of th thigh, but takes an upward course.

The deeper layer of superficial fascia represents the tunica abdominalis c quadrupeds, which is composed almost entirely of elastic tissue, and serves as a important adjunct to the abdominal parietes.

The separation, entirely artificial, of the superficial fascia int a superficial fatty layer and a deep membranous layer, the so-calle* deep fascia, obtains "throughout the body, but in the lower part c the anterior abdominal wall is more apparent than elsewhere. Th reasons are (1) the frequent accumulation of fat in this region makin the superficial layer very distinct; (2) the presence in considerabl abundance of strong fibres, some of which are said to be elastic, ii the deep layer, accentuating its membranous character; (3) the exist ence beneath the deep layer of an aponeurosis, and the consequen tendency for the formation of a membranous covering. While else where the two layers are named superficial and deep fascia respectively it is customary in the region of the anterior abdominal wall for historica reasons to speak of both layers as forming the superficial fascia, and t< make no reference to any deep fascia.

Cutaneous Nerves. —The anterior cutaneous nerves are the termina branches of the lower five intercostal nerves and of the anterior primar division of the twelfth thoracic nerve (subcostal nerve). Having emerged through the anterior wall of the sheath of the rectus abdomini in a straggling manner, they give a few twigs inwards, and then turi outwards to supply the anterior abdominal integument, in which the> communicate with the anterior branches of the lateral cutaneous nerves The" nerves pursue a tortuous course, and are therefore not so subjec to strain during the movements of the anterior abdominal wall as the^ would be if their course were straight.

The anterior cutaneous branch of ilio-hypogastric nerve pierces th< external oblique aponeurosis about 1 inch above the superficial inguina ring, and is distributed to the skin of the suprapubic region. It i‘ serially continuous with the anterior cutaneous nerves.

The skin below the xiphoid process is supplied by the seventh thoracic nerve that on a level with the umbilicus by the tenth thoracic; and that over the lowe: half of the infra umbilical region by the subcostal and the ilio-hypogastric.

The lateral cutaneous nerves are branches of the lower five inter costal nerves. Having emerged between the digitations of the externa oblique muscle in the mid-axillary line, each divides into an anterio] and a posterior branch. The posterior branch turns backwards tc supply the skin over the lower part of the back. The anterior brand passes forwards to supply the skin of the anterior abdominal wall communicating with an anterior cutaneous nerve.

Cutaneous Arteries.— The superficial external pudendal artery arises from the femoral about f inch below the inguinal ligament, after which it pierces the femoral sheath and cribriform fascia. Having emerged through the saphenous opening, it passes inwards and upwards over the spermatic cord or ligamentun


THE ABDOMEN


711

sres of the uterus, according to the sex, to be distributed to the skin of the uprapubic region, the adjacent portion of the scrotum in the male and the ibium majus in the female, and the dorsum of the penis by a branch which xtends as far as the prepuce, lying lateral to the dorsal artery of penis. The essel in its course gives branches to the inguinal glands, and the covering of he spermatic cord, or of the ligamentum teres of the uterus. It anastomoses nth the following arteries: (a) the cremasteric branch of the inferior epigastric,


Fig. 420. —Cutaneous Nerves of the Trunk (Antero-lateral

View) (after Henle).

1-12, anterior cutaneous; 2-12, lateral cutaneous.


Jr in the female the artery to the ligamentum teres of the uterus; (b) its fellow }f the opposite side; (c) the deep external pudendal; (d) the superficial perineal; md (e) the dorsal artery of penis.

The venae comites of this artery terminate in one vessel, which joins the long ■saphenous vein.

The superficial epigastric artery arises from the femoral about | inch below the inguinal ligament. Having pierced the femoral sheath and cribriform fascia, 3r the outer border of the saphenous opening, it turns upwards over the inguinal













712


A MANUAL OF ANATOMY


ligament a little to the inner side of the centre, and then ascends as high as t level of the umbilicus. As it turns upwards it supplies branches to the supe ficial inguinal glands, and on the abdominal wall anastomoses with branches the inferior epigastric artery.

There are at first two venae comites with this artery, but these eventual join to form one vessel which terminates in the long saphenous vein. T\ radicles of these venae comites communicate with the following vessels: the par umbilical veins in the region of the umbilicus, which lie on the surface of t] ligamentum teres of the liver, and communicate with the branches of the vei portae; the lateral thoracic and subscapular veins, upon the side of the thora which are tributaries of the axillary vein; and the superior epigastric veir which are tributaries of the internal mammary veins. In the superficial epigastr vein and its tributaries the blood can flow in either direction. In cases of port obstruction the venous anastomoses in the neighbourhood of the umbilicus u infrequently become engorged, resulting in a system of subcutaneous vei] radiating from the umbilicus and known as the Caput Medusce.

The superficial circumflex iliac artery often arises in common with the supe ficial epigastric from the femoral about inch below the inguinal ligamen Having pierced the fascia lata on the outer side of the saphenous opening, passes outwards below the outer part of the inguinal ligament to the anteri< part of the iliac crest, where it is distributed to the adjacent abdominal integi ment. In its course it gives branches to the iliacus and sartorius muscles ar the outer inguinal glands, and it anastomoses with (a) the deep circumflex ilk of the external iliac, and (b ) the superior gluteal of the internal iliac.

The vein corresponding to this artery terminates in the long saphenous veil

The anterior cutaneous arteries are derived from the inferior and superb epigastric arteries. They emerge through the anterior wall of the sheath of tl rectus abdominis in an irregular manner, and accompany more or less close] the anterior cutaneous nerves.

The veins corresponding to these arteries terminate in the inferior and superb epigastric veins.

The lateral cutaneous arteries are branches of the lower five posterior inte costal and subcostal arteries, and they emerge with the lateral cutaneous nerv between the digitations of the external oblique muscle in the mid-axillary line

The veins corresponding to these arteries are tributaries of the lower frv posterior intercostal and subcostal veins.

Superficial Lymphatics. —The superficial lymphatics below the lev< of the umbilicus accompany the superficial epigastric vessels, an terminate in the superficial inguinal glands. Those above the lev( of the umbilicus pass to the axillary glands. The superficial lymphatic of the lateral abdominal wall terminate in two ways. Some accompan the superficial circumflex iliac vessels, and terminate in the superfick inguinal glands; others accompany the abdominal branches of th lumbar arteries, and terminate in the deeply-placed aortic group c lumbar glands. For the deep lymphatics of the antero-latera .1 at dominal wall, see p. 733.

Penis—Coverings. —The skin at the free extremity of the glam being doubled upon itself, passes backwards until it reaches the cor striction behind the corona glandis called the neck. Here it is reflecte* forwards, closely investing the neck, corona glandis, and body of th glans. On reaching the lips of the external orifice of urethra it become continuous with the mucous membrane of the urethra. The ski] covering the glans is provided with papillae, but these do not appea on the surface, The duplicature, which the skin forms in the regio]


THE ABDOMEN


7 i 3


the glans, is called the prepuce. The under part of the prepuce connected to the under surface of the glans by a median, laterally npressed, triangular fold, called the frenulum, which extends as far the lower part of the external orifice of urethra. Sebaceous glands ve been described by Kolliker as present on the inner surface of the ipuce, particularly in the region of the frenulum, and less constantly the glans and at the corona. Glands in these regions were first ted by Tyson in the orang, and are sometimes in consequence named er him. Whether they exist in man or not is a matter of some doubt; •tain histologists do not hesitate to deny their presence, and attribute 3 so-called secretion under the prepuce—the smegma preputii —to the making down of desquamated epithelial cells. The dartos muscle is uated immediately beneath the skin, and is destitute of adipose sue. It is continuous with fatty superficial and deeper membranous

Superficial Dorsal Vein (Deep) Dorsal Vein Dorsal Artery Dorsal Nerve

Corpus Cavernosum Penis Artery of Corp. Cav. Penis Fascial Sheath

Corpus Spongiosum Urethra

Artery of Corp. Spong.


Fig. 421.—Diagram of Section across the Penis (Enlarged).

/ers of the fascia of the anterior abdominal wall, and with the dartos iscle of the scrotum, like which latter it contains involuntary muscular •sue. The fascial investment or sheath is rich in elastic fibres, and vers the penis, with the exception of the glans. It is situated beneath e dartos muscle, from which it is separated by loose areolar tissue, id at the neck blends with the skin of the glans. Towards the root the organ it receives expansions from the ischio-cavernosus and ilbo-spongiosum muscles, and covers the dorsal vessels and nerves.

this way the dorsal vein is compressed during the action of these, t the root of the organ the fascial investment blends with the two Vers of the suspensory ligament.

Suspensory Ligament. —This ligament, sometimes called the deep -spensory ligament, is strong and triangular in outline, and is combed of fibrous and elastic tissues. It is attached superiorly to the ont of the symphysis pubis, where it is single, and inferiorly it divides








A MANUAL OF ANATOMY


7 M

into two laterally-disposed, diverging laminae, which blend with t fascial sheath of the penis. The interval between the two laminae occupied by the dorsal vessels and nerves. The ligament is part formed from fibres continued into it from the aponeurosis of t external oblique muscle.

The Dorsal Arteries. —For the description of these arteries, s

p. 688.

In addition to the dorsal artery, the skin of the organ is suppli< by the superficial external pudendal arteries, the branch from each these vessels lying lateral to the dorsal artery or penis.

Deep Dorsal Vein. —The tributaries which give rise to this ve come from the glans and corpora cavernosa. They form at first tv dorsal veins, but these soon unite into one vessel, which passes bac' wards in the middle line, occupying the groove between the corpo: cavernosa, where it is under cover of the fascial sheath of the pem At the root of the organ it passes between the two laminae of the su pensory ligament, and then between the inferior and transverse perine ligaments. In this part of its course it communicates with the venoi plexus in the sphincter urethrae muscle in which the internal pudend venae comites arise. On entering the pelvis it divides into two branche

which terminate in the right ar left portions of the prostat plexus of veins.

In addition to the deep dors vein, there are two superficial dors veins which take up blood from tl glans and skin. Each accompani a branch of the superficial extern pudendal artery, and opens into tl superficial external pudendal vein

For a description of tl dorsal nerves of the penis, sf p. 689.

The relation of the stru< tures on the dorsum of the peni from the middle line outward is as follows: deep dorsal veil dorsal artery, and dorsal nerv Composition of the Penis.The penis has two surfacesupper or dorsal, and under c scrotal. Viewed as a who! the organ is composed of thrf cylindrical bodies—namely, tw corpora cavernosa and a corpi spongiosum—closely applied t each other. It is divisible int a root, body, neck, and glans. The root is formed by the crura ( the corpora cavernosa, which are attached to the inner margins (


Fig. 422.—Plans to show Structure of Penis.

A, ventral aspect; B, lateral; C, terminal, showing glans covering the ends of corp. cav. penis ; CCP, corp. cav. penis ; CCU, corp. spongiosum ; GL, glans ; susp., suspensory ligament.





THE ABDOMEN


7 i 5


3 ischio-pubic rami. The upper surface of the root is also connected the symphysis pubis by the suspensory ligament. The upper or rsal surface of the body is formed by the corpora cavernosa, the der or scrotal surface being formed by the corpus spongiosum in the ddle line and the corpora cavernosa at either side. The corpora /ernosa and corpus spongiosum at their meeting become flattened, d so the shape of the body is subcylindrical. The corpora cavernosa minate in round extremities, in front of which the corpus spongiosum rns upwards, and, becoming much enlarged, forms the glans penis. ie neck is the constriction between the body and the glans. The ins penis is formed by the corpus spongiosum. It is somewhat tiical, and has been likened to an acorn, from which circumstance it s been called the balanus. At the base there is a wheel-like rim, Lied the corona glandis. The part anterior to the corona is called 3 body of the glans, and presents anteriorly a vertical fissure Lied the external orifice of urethra. For the structure of the penis, i p. 682.

Lymphatics. —These are divided into a superficial and deep set. The lymphatics of the prepuce form a finely meshed plexus which the region of the corona communicates with the lymphatics of the ms. The collecting trunks from the plexus pass backwards, forming single median vessel, double bilateral, or more frequently multiple ssels, which run on the dorsum of the penis and receive as they go butary lymphatic vessels from the suprathecal portion of the penis. 1 reaching the symphysis the vessels turn some to the right, others the left—a single vessel dividing—and running immediately under e skin terminate in the superficial inguinal glands. Owing to the ie anastomosis which exists between the vessels, the glands of either le may become infected from a septic focus on one side.

The lymphatics of the glans form a very finely meshed plexus, e collecting trunks from which pass downwards, at the side of the 3 nulum, and then, after communicating with the lymphatics of the epuce and the anterior part of the urethra, pass dorsally surrounding e corona glandis, after which they run backwards along the dorsum irallel with those from the prepuce, but lying deep to, instead of perficial to, the sheath of the penis, receiving in their course tributary mphatics from the intrathecal portion of the penis. On reaching the mphysis they form a plexus in which occasionally small presymphysial mph nodules are to be found, and then pass outwards either to the

e P inguinal glands or through the femoral and inguinal canals to the ands forming the medial and lateral chains respectively of the external ac glands.

The lymphatics of the clitoris correspond with those of the penis. Scrotum. —The wall of the scrotum is complex, and its constituent irts will be made more evident if they are enumerated in the order which the testes receive them in their original descent from the )dommal cavity. It may be premised that the descent of each stis is preceded by a process of peritoneum, called the processus


716


A MANUAL OF ANATOMY


vaginalis, the lower part of which remains permanent as the tun vaginalis testis, the upper part becoming obliterated, and be: normally represented in the adult, if at all, by a fibrous cord. 1 constituent parts of the scrotal wall, enumerated from within outwar are as follows: tunica vaginalis testis, subperitoneal areolar tiss internal spermatic fascia, cremasteric muscle and fascia, exter: spermatic fascia, dartos muscle, and skin.


Fig. 423.—Plan of Structure of Scrotal Walls.

TV, tunica vaginalis; C, cord; T, testis. The coverings, deep to the corrugated skin, are (1) external spermatic fascia (from external oblique) shown by a fine line; (2) dotted line, cremasteric fascia from internal oblique; (3) interrupted line, internal spermatic fascia from trailsversalis fascia.


The tunica vaginalis testis is the park

layer of the tunica vaginalis.

The subperitoneal areolar tissue is compo of areolar and adipose tissues, and a cert amount of plain muscular tissue.

The internal spermatic fascia is derh from the fascia transversalis at the margin' the deep inguinal ring, in which vicinity il called the infundibuliform fascia. In assoc tion with the subperitoneal areolar tissue forms the fascia propria of Cooper.

The cremasteric fascia is composed striated muscular tissue, forming the cremas muscle, and of areolar and elastic tissues, is traceable superiorly to the lower border the internal oblique, the deep surface of 1 inguinal ligament, and the pubic tubercle.

The external spermatic fascia is compos of connective tissue, and is derived from t intercrural fibres which extend between t columns of the superficial inguinal ring. T above three layers of fasciae are so closely : corporated as to be indistinguishable frc one another.

The dartos muscle lies immediately with the skin. It is derived from the fatty sup( ficial and deeper membranous layers of t fascia of the anterior abdominal wall. It chiefly composed of plain muscular tissue, b it also contains fibro-areolar and elastic tissue and it has a brick-red colour.

The skin is thin, very extensible, dark colour, and provided with hairs, sweat-gland and sebaceous glands. It is more depende: on the left side on account of the low position of the left testis. In the middle lii it presents a raphe,which is continuous behir with that of the anterior part of the perineur


and in front with that on the under surface the penis. This raphe is an external indication of the bilateral symmetry the scrotum. On either side of the raphe the skin is thrown into a number transverse rugae, the corrugated condition being due to the plain muscular tiss of the dartos muscle.


The interior of the scrotum is divided into two compartments each of which lodges the corresponding testis. This division is effecte by the scrotal septum, formed by the fusion of the contiguous walls c the two scrotal chambers, except the skin, which forms one continuou investment to both. Interiorly the septum is attached to the botton






THE ABDOMEN


717


he scrotal chamber and superiorly to the under surface of the root he penis.

Blood-supply. —The scrotum receives its chief arterial supply from superficial and deep external pudendal branches of the femoral of h side, and the superficial perineal branches of the internal pudendal 3ries.

The veins corresponding to these arteries terminate in the long henous and internal pudendal veins.

The cremasteric branch of the inferior epigastric of each side also es part in the supply of the scrotal wall, the venous blood being irned into the inferior epigastric vein, which at its termination is lie.

Lymphatics. —The lymphatics of the scrotum are divided into a erior and an inferior set. They pass upwards and outwards to ninate in the superior and inferior groups respectively of the superil inguinal glands.

Nerve-supply. —The nerves of the scrotum are as follows: (1) the

ral and medial posterior scrotal branches of the pudendal; (2) the y perineal nerve from the posterior cutaneous nerve of thigh; the ilio-inguinal from the lumbar plexus; and (4) twigs of the ital branch of the genito-femoral nerve from the lumbar plexus. Development. —The genital swellings.

Muscles of Abdominal Wall—Obliquus Externus Abdominis— Origin. 'he outer surfaces of the lower eight ribs by means of eight flesh) 7 s, the upper five of which interdigitate with slips of the serratus erior, and the lower three with slips of the latissimus dorsi. Insertion. —fi) The anterior half of the outer lip of the iliac crest fleshy fibres. (2) By means of an aponeurosis into (a) the linea a, and so into the xiphoid cartilage and symphysis pubis; (b) the >ic tubercle and crest of the opposite side by means of the reflected t of inguinal ligament; (c) the pubic tubercle and anterior superior 2 spine of the same side by means of the inguinal ligament; and the first inch of the pectineal line by means of the pectineal part

he inguinal ligament. Nerve-supply .—The lower five intercostal nerves and the subcostal

ve.

Action. —(1) The two muscles, acting conjointly, diminish the size of the ominal cavity, and so compress the viscera, as in defaecation. (2) The two ides, acting conjointly from their origins, raise the front part of the pelvis flex it upon the thorax. (3) Acting conjointly from their insertions, they the thorax upon the pelvis, the vertebral column being also flexed in the er thoracic and lumbar regions; but, if the column is fixed, the two muscles ress the lower eight ribs. (4) One muscle, acting from its origin, is a lateral or of the pelvis. When it acts from its insertion it flexes the thorax towards )wn side and rotates it to the opposite side.

Most of the fibres of the external oblique pass downwards and wards, coinciding in direction with those of the external intercostal scles. The only parts of the muscle which are free are the part


718


A MANUAL OF ANATOMY


between the last rib and the iliac crest, and the part opposite the pc crest. The aponeurosis attains its greatest width and strength and below, the level of the anterior superior iliac spine, and ii narrowest opposite the umbilicus. Superiorly it gives origin to fit of the pectoralis major. Crossing the fibres of the aponeurosis in upward and inward direction there are several superadded fibres, the lower part of the abdominal wall these are specially well mark


Pectoralis Major


Serratus Anterior _


Latissimus Dorsi

Obliquus Externus Abdominis


Lumbar Triangle


Middle Tendinous , l|u i Intersection


^.-Umbilicus


_Rectus Abdominis


_.Anterior Superior

Iliac Spine


.Inguinal Ligament


Spermatic Cord at 4 jri- Superficial Inguinal Ring


Fig. 424.—The External Oblique Muscle.


and are here spoken of as the inter crural fibres. Under this nai they spring from the outer third of the inguinal ligament, whence th pass upwards and inwards in a curved manner, the convexity bei downwards. On arriving at the upper and outer part of the superfic inguinal ring they extend from one column to the other. They rou off and close the ring, and are prolonged upon the spermatic cord form the external spermatic fascia.












































THE ABDOMEN


710

The following parts of the external oblique aponeurosis require cial description: inguinal ligament, pectineal part of inguinal ligaat, the reflected part of inguinal ligament, the superficial inguinal y, and the linea alba.

Inguinal ligament (Poupart’s) is the thickened lower border of the ernal oblique aponeurosis, which is folded backwards. Laterally s attached to the anterior superior iliac spine, and medially to the )ic tubercle, from which it is reflected outwards and backwards >n the pectineal line for fully 1 inch to form its pectineal part. The iment is curved, the convexity being directed downwards and outrds, due to the attachment of the iliac lamina of the fascia lata to its 'er border. The convexity is greatest when the thigh is extended, lucted, and rotated outwards, in which position the fascia lata on front of the thigh is tightened.

Relations — Superficial. —Skin; the superhcial and deeper layers of the fascia he anterior abdominal wall; superficial epigastric vessels, a little to the inner ! of the centre; superficial circumflex iliac vessels just below its outer part; and superficial inguinal glands along its lower border. Deep .—Internal oblique, lsversus abdominis, and cremaster muscles, which take part of their origin n its deep surface; the ilio-psoas and pectineus; the fascia transversalis and

ia iliaca, which are attached to its lateral portion, forming a canal containing deep circumflex iliac vessels; the fascia transversalis, forming the anterior 1 of the femoral sheath; the deep femoral arch, femoral vessels, deep inguinal ids, and lymphatic vessels; the femoral and genito-femoral nerves, and the

ral cutaneous nerve of thigh. The deep femoral arch is a thickening of the fascia transversalis as it passes mwards beneath the inguinal ligament to form the anterior wall of the femoral ith. The thickening is due to superadded fibres which extend inwards from centre of the inguinal ligament on its deep aspect to the pectineal line, where y are attached behind its pectineal part near its base.

The pectineal part of inguinal ligament (Gimbernat’s) is the reflection

he inguinal ligament from the pubic tubercle along the pectineal line, length is fully 1 inch, and it is triangular, the apex being at the

>ic tubercle. It presents three borders and two surfaces. Two of ! borders are fixed, one, called the inguinal border, being continuous

h the inner end of the inguinal ligament, and the other, called the tineal border, being implanted on the pectineal line. The third ~der is free, and is called the base. It is sharp, wiry, and concave, I is situated immediately to the inner side of the femoial ring. The 'faces of the ligament are femoral and abdominal. They occupy oblique plane, the femoral surface looking downwards, forwards, and ?htly outwards, whilst the abdominal surface looks upwards, backrds, and slightly inwards. This latter surface, along its line of juncn with the inguinal ligament, forms the floor of the inguinal canal in lower third, where it supports the spermatic cord in the male, and

ligamentum teres of the uterus in the female. The fascia transrsalis is attached to the base of the ligament on its abdominal }ect, and the conjoint tendon and fascia transversalis lie behind it the pectineal line. A few of the fibres of the superior cornu of the dienous opening terminate on the femoral surface of the ligament,


720


A MANUAL OF ANATOMY


and the pectineus muscle and pubic lamina of the fascia lata are front of its pectineal attachment.

The reflected part of inguinal ligament (triangular fascia), also knov as the ligament of Colies, is situated behind the spermatic cord ar superior crus of the superficial inguinal ring. Its fibres are derive from the external oblique aponeurosis of the opposite side; havir crossed the linea alba, they gain insertion into the pubic tubercle ar


Fig. 425. —Anterior View of Muscles and Aponeuroses.

External oblique removed on one side to expose the internal oblique. Termini cutaneous branches of nerves shown on one side, coming through sheat of rectus.

crest. A portion of the fascia is seen lying in the lower and inner par of the superficial inguinal ring.

The superficial inguinal (external abdominal) ring is an opening fi the aponeurosis of the external oblique, and is situated immediately above the pubic tubercle. It serves for the passage of the spermatf cord in the male, and the ligamentum teres of the uterus in the female In the natural condition no opening is perceptible, the intercrura fibres rounding it off, and being prolonged downwards upon the trans mitted structure. When the intercrural fibres and fascia have beer removed, the ring is seen to be formed in the following manner: the







THE ABDOMEN


721


Dres of the external oblique aponeurosis, as they approach the os ibis, are disposed in two diverging bundles. One bundle, which presents the inner end of the inguinal ligament, is fixed to the pubic ibercle. The other bundle passes to be attached to the front of the unphysis pubis, where its fibres decussate with those of its fellow

the opposite side, the fibres from the right side being superficially laced. An interval is thus left between these diverging bundles, hich is widest at the lower and inner part, where it corresponds with

Pectoralis Major


i portion of the pubic crest. This interval is the superficial inguinal ■ing. Its direction is upwards and outwards, and it is parallel with -he inner part of the inguinal ligament. Its length is from 1 inch to £2 inches, and its breadth at the base about J inch. It is triangular, the base being formed by part of the pubic crest, and the apex being directed upwards and outwards. The margins of the ring are called the crura. From the oblique position of the ring one crus is lateral and inferior, the other being medial and superior. The superior crus, which is thin and straight, passes to be attached to the front of the

46










































722


A MANUAL OF ANATOMY


symphysis pubis. The inferior crus is at first thin, but it soon becomes thick and prismatic, and is fixed to the pubic tubercle. It presents superiorly a concavity which lodges the spermatic cord in the male and the ligamentum teres of the uterus in the female. The external spermatic fascia is attached to both crura, lying upon the spermatic cord. Certain of the lower intercrural fibres are directed with their concavity downwards, and, passing beneath the cord, serve to round off the lateral margins of the ring. The presence of the fascia explains why urine, extravasated into the perineum, does not find its way into the inguinal canal. Within the lower and inner part of the ring is the reflected part of inguinal ligament, and directly behind the ring is the conjoint tendon, which strengthens what would otherwise be a weak part of the abdominal wall. The ring is smaller in the female than in the male.

The linea alba has been already described (see p. 704).

The lumbar triangle (triangle of Petit) is only present when the latissimus dorsi and external oblique do not meet. It is situated immediately above the centre of the iliac crest, and is bounded in front by the posterior border of the external oblique, behind by the anterior border of the latissimus dorsi, and below by the central portion of the iliac crest. It is covered only by skin and fascia, and its floor is formed by a part of the internal oblique. In this situation a lumbar hernia may occur, or a lumbar abscess may find its way to the surface.

Obliquus Internus Abdominis — Origin. —(1) The deep or abdominal surface of the inguinal ligament over its outer half or two-thirds;

(2) the middle lip of the iliac crest over its anterior two-thirds; and

(3) the posterior layer of the lumbar fascia of the transversus abdominis.

Insertion. —(1) The lower borders of the cartilages of the lower

three ribs; (2) the lower borders of the cartilages of the seventh, eighth, and ninth ribs, and the side of the xiphoid process of the sternum; (3) the linea alba in its whole length; (4) the pubic crest; and (5) the medial portion of the pectineal line for \ inch.

Nerve-supply. —This is similar to that of the external oblique, with the addition of twigs from the ilio-inguinal nerve and the anterior branch of the ilio-hypogastric, both of which are derived from the lumbar plexus, more particularly the first lumbar nerve.

Action —This is similar to that of the external oblique. When the right internal oblique acts simultaneously with the left external oblique, the trunk is rotated to the right side, and vice versa. To understand this action, it is to be noted that the fibres of the internal oblique of one side coincide in direction with those of the external oblique of the opposite side.

Most of the fibres pass upwards and forwards across those of the external oblique, coinciding in direction with those of the internal intercostal muscles. The fibres from the inguinal ligament, however, pass downwards and inwards, and join the corresponding fibres of the transversus abdominis to form the conjoint tendon. The aponeurosis is broader above than below. In its upper three-fourths it divides at


THE ABDOMEN


723


e outer border of the rectus abdominis into two laminae, one of which sses in front of the muscle and the other behind it. The anterior Inina joins the aponeurosis of the external oblique, and the posterior mina joins the anterior aponeurosis of the transversus. It is this tter lamina which has an insertion into the seventh, eighth, and ninth >stal cartilages and xiphoid process. In its lower fourth the aponeurosis r a in divides at the outer border of the rectus, but the division is not ! apparent; the fibres forming the anterior lamina pass as before in 3 nt of the rectus to join the aponeurosis of the external oblique; L e fibres forming the posterior mina, on the other hand, curve iwnwards, and, passing along ie outer border of the rectus, iin the aponeurosis of the transsrsus, the fibres of which are milarly directed, to form the Dnjoint tendon, which in certain ises may be said to form a slot 1 which the outer border of the ictus fits. The fibres of the mscle which arise from the inuinal ligament are at their rigin in front of the spermatic ord as it lies in the upper third f the inguinal canal. They then rch over it, and finally descend >ehind it as it lies in the lower wo-thirds of the inguinal canal, n this latter situation the fibres Lave terminated in the conjoint endon.

Cremaster — Origin .—The deep .spect of the inguinal ligament n its inner part. A few fibres ire also derived from the lower )order of the internal oblique.

Qie fibres descend in a series )f loops upon the outer and interior aspects of the spermatic cord. The lowest loops reach the

unica vaginalis of the testis, upon the upper part of which they spread out in an arched manner, some of the fibres terminating on t. The other loops are successively shorter from below upwards, and ascend on the inner and posterior aspects of the cord, where they become tendinous and indefinite, to gain insertion into the pubic tubercle and anterior lip of the pubic crest. The loops of the muscle are separated by intervals occupied .by areolar tissue. This combination of muscular loops and areolar tissue forms the cremasteric fascia. The cremaster muscle lies in series with the lower border of the internal


Fig. 426A. —Diagram to show how the Lower Fibres of Internal Oblique form a Cremaster Muscle (CM)

CONTINUOUS WITH CREMASTERIC FASCIA (CF).

I.Sp.F., internal spermatic fascia;

C, conjoint tendon.









724


A MANUAL OF ANATOMY


oblique, and is peculiar to the male. It is occasionally represented i the female by a few fibres which descend on the ligamentum teres c the uterus in the inguinal canal.

Nerve-supply .—The genital branch of the genito-femoral nerv from the lumbar plexus, more particularly from the first and th ventral division of the second lumbar nerves.

Action .—To support and raise the testis towards the superfici; inguinal ring. The fibres composing the muscle are of the striate variety, but the action is involuntary, and of a reflex character.


Cremasteric Reflex. —The afferent nerve involved in the cremasteric reflex either the ilio-inguinal, which is distributed to the side of the scrotum and inn( side of the thigh, or the femoral branch of the genito-femoral, which is distribute to the integument over the femoral triangle. The efferent nerve is the geniti branch of the genito-femoral.

Transversus Abdominis — Origin. — : (i) The deep aspect of the it guinal ligament over its outer third; (2) the inner lip of the iliac ere:: over its anterior two-thirds; (3) the lumbar fascia, which by its postern

















THE ABDOMEN


725


xr is connected with the spinous processes of the lumbar and sacral

tebne and the posterior fourth of the outer lip of the iliac crest, by middle layer with the tips of the lumbar transverse processes, and its anterior layer with the anterior surfaces of the lumbar transrse processes; and (4) the inner surfaces of the cartilages of the ver six ribs by six slips which interdigitate with slips of the iphragm.

Insertion. —(1) The linea alba; (2) the pubic crest; and (3) the Mial portion of the pectineal line for 1 inch.

Nerve-supply. —This is similar to that of the internal oblique. Action. —To diminish the capacity of the abdominal cavity, and compress the viscera. To a limited extent the two muscles aid e external and internal oblique muscles in elevating the pelvis, flexing e thorax, and depressing the ribs.

Most of the fibres pass transversely forwards, and terminate in the iterior aponeurosis. The fibres, however, from the inguinal ligament iss downwards and inwards, and join the corresponding fibres of the ternal oblique to form the conjoint tendon. The anterior aponeurosis narrow above, but broad below. The narrowness above is due to Le fact that for some distance below the xiphoid process the muscular ires of the transversus are continued behind the rectus, and only scome aponeurotic on nearing the linea alba. In its upper threelurths the aponeurosis passes behind the rectus muscle, but in its wer fourth it passes down along its lateral margin. The transversus idominis is continuous superiorly with the transversus thoracis muscle, id its lower border is free where it arches over the spermatic cord or le ligamentum teres of the uterus.

For the posterior aponeurosis of the muscle, see p. 840.

Conjoint Tendon. —This is the tendon which gives a common inseron to the fibres of the internal oblique and transversus abdominis luscles which arise from the inguinal ligament. It is inserted into [) the pubic crest, and (2) the medial portion of the pectineal line ir 1 inch. The tendon is formed principally by the transversus bdominis, which extends for 1 inch along the pectineal line, whilst the iternal oblique only extends along that line for \ inch.

Relations — Superficial .—The structures in front of the conjoint tendon, from he middle line outwards, are as follows: the lower part of the superior crus of the uperficial inguinal ring; the triangular fascia; the insertion of the cremaster; ectineal part of inguinal ligament; the inner part of the inguinal ligament; and he spermatic cord. Deep .—The fascia transversalis.

The conjoint tendon varies greatly in development, and in many cases is tardly distinguishable. As a rule, it covers the inner two-thirds of the floor »f the inguinal triangle, where it lies behind the inner two-thirds of the inguinal anal, and has the spermatic cord, or the ligamentum teres of the uterus, as a uperficial relation. It also lies directly behind the superficial inguinal ring, and 0 strengthens what would otherwise be a weak part of the abdominal wall.

Interfoveolar Ligament. —In normal circumstances the conjoint tendon is united to the first inch of the medial portion of the pectineal line. Sometimes, lowever, the anterior aponeurosis of the transversus abdominis is prolonged outwards beyond the normal limit of the conjoint tendon in the form of a thin


726


A MANUAL OF ANATOMY


semilunar expansion which extends as far as the inner and lower parts of deep inguinal ring, and is attached interiorly to the deep crural arch. 1 semilunar expansion of the conjoint tendon is known as the interfoveolar ligame Its concavity is directed outwards, and, when present, it covers the outer th of the floor of the inguinal triangle, where it lies behind the spermatic cord, i is closely connected with the subjacent fascia transversalis, to which it imps strength.

An inspection of the external oblique, internal oblique, and tra: versus abdominis muscles shows that they cross each other at differc angles, the external oblique passing downwards and forwards, t internal oblique upwards and forwards (these two muscles thus crossi like the limbs of the letter X), and the transversus horizontally forwan They thus form an intricate lattice-work which renders the abdomii wall very strong, and is a powerful safeguard against hernial pi trusions.

Rectus Abdominis — Origin .—This muscle arises by two hea< both of which are tendinous. The lateral head, broad and flat, ark from the pubic crest, and the medial head, narrow and somewhat rour from the fibrous structures in front of the symphysis pubis, where if closely connected with its fellow of the opposite side. The two hea join about i inch above the symphysis pubis.

Insertion .—By means of three flat slips, which are at first flesl and subsequently tendinous, into the anterior surfaces of the fift sixth, and seventh costal cartilages. The most medial slip is som times partially inserted into the side of the xiphoid process of t sternum.

Nerve-supply .—The lower five intercostal nerves and the subcosf nerve.

Action .—The action is similar to that of the two oblique ai transversus muscles, with the exception that it does not produ lateral rotation of the thorax.

The muscle is long, flat, and strap-like, its fibres being direct< vertically upwards by the side of the linea alba. It is narrow belc and broad above, its greatest breadth being about 3 inches. Belc the umbilicus the two muscles are very near each other, the interv between them being not more than about J inch. Above the umbilicr however, the muscles are separated by an interval of about J inc' Each muscle is marked by tendinous intersections which cross it in somewhat irregular manner at certain intervals. They are usual, three in number, and are situated as follows: one at the level of tl umbilicus, a second opposite the margin of the thorax, and a thii about midway between these two. Sometimes there is a fourth inte section, which crosses the muscle a little below the umbilicus, but th one is faint, and does not usually extend the whole width. These inte sections, which do not usually penetrate to the posterior surface, ma out the upper part of the muscle into quadrangular areas, and ai firmly bound to the anterior wall of its sheath. Above the level of tl umbilicus, therefore, the interior of the sheath, anterior to the muscl is divided into distinct compartments.


THE ABDOMEN


727


The tendinous intersections are the intersegmental parts of the lateral sheets )f mesoderm. The muscles of the abdominal wall, including the rectus, are 'ormed from ventral downgrowths derived from the somites, and therefore segmental in nature. The downgrowths pass ventrally in the lateral mesodermal sheet, and the parts of the lateral sheet remaining between the separate downgrowths are hence intersegmental; they are best marked between the ventral extremities of the downgrowths, which are not so broad here. The lateral sheet mly forms the simple connective tissues in the trunk, never muscular tissue, md in most cases the intersegmental lines show as the tendinous lines in the rectus; in some animals, however, such as the crocodile, the connective tissue becomes fibro-cartilaginous in nature, making what are sometimes termed abdominal ribs ' in these animals. In man they serve the purpose of strengthening the muscle.

Pyramidalis — Origin .—The front of the pubic crest.

Insertion .—The linea alba for 2 inches or more above the symphysis pubis.

Nerve-supply .—The subcostal nerve.

Action .—To render tense the linea alba.

The muscle is sometimes present only on one side; sometimes it is absent on both sides; and sometimes it is double on one or both sides. In man it is a small muscle, and vestigial like the plantaris; but it attains a large size in marsupials and monotremes, and is attached to the epipubic bone of these mammals. It is frequently separated in man from the rectus by a fascial expansion from the conjoint tendon.

Sheath of Rectus Abdominis. —Above the level of the thoracic margin the sheath of the rectus is deficient posteriorly, and is formed anteriorly by the aponeurosis of the external oblique; from the thoracic margin to a level about midway between the umbilicus and the symphysis pubis the anterior wall is formed by the anterior lamina of the internal oblique aponeurosis and the external oblique aponeurosis, the two being closely connected, and the posterior wall is formed by the posterior lamina of the internal oblique aponeurosis and the anterior aponeurosis of the transversus abdominis, these two being likewise closely connected. Below a line midway between the umbilicus and symphysis the anterior wall is formed by the aponeurosis of the external oblique reinforced by fibres derived from the aponeurosis of the internal oblique, and the posterior wall is only represented by the fascia transversalis, since part of the aponeurosis of the internal oblique here blends with the aponeurosis of the transversus to form the conjoint tendon, which, instead of passing inwards, curves downwards, skirting the lateral border of the rectus.

The line along which this transition occurs is curved with the concavity downwards, and is known as the arcuate line (fold of Douglas). This so-called fold is extremely variable, sometimes scarcely apparent, at other times multiple. When well developed it is traceable to the linea alba at its upper and inner extremity, and to the pubic crest, where it blends with the inner edge of the conjoint tendon at its lower and outer extremity. It thus bounds supero-laterally a large oval area, within which the inferior epigastric vessels pierce the fascia trans


728


A MANUAL OF ANATOMY


versalis, and so enter the sheath of the rectus. These vessels, as th course upwards, pass anterior to the fold.

The contents of the sheath are as follows: the rectus abdomin pyramidalis, inferior epigastric vessels, superior epigastric vessels, ai terminal parts of the lower five intercostal and subcostal nerves.

Relation of Structures at the Pubic Crest. —The relation of structures fn

before backwards is as follows:

1. The reflected part of inguinal ligament.

2. The conjoint tendon splitting medianly to enclose the lateral margins the pyramidalis and rectus.

3. The pyramidalis.

4. The outer head of the rectus abdominis.

5. The fascia transversalis.

A few fibres of the cremaster are inserted into the pubic crest close to the pul tubercle.

Relation of Structures at the Medial Portion of the Pectineal Line. —The relati<

of structures from before backwards is as follows:

1. The pubic lamina of the fascia lata, incorporated with which is the pectinc (ligament of Cooper) ligament.

2. The pectineus.

3. Pectineal part of inguinal ligament.

4. The conjoint tendon.

5. The fascia transversalis and the deep femoral arch.

Deep Nerves of the Abdominal Wall. —The lower five intercost nerves, after leaving the intercostal spaces, lie between the intern oblique and transversus abdominis, and pass downwards and forwar< to the outer border of the rectus. Here they pierce in succession tl posterior wall of the sheath, the rectus, and the anterior wall of tl sheath, after which they terminate as the anterior cutaneous nerve In their course they supply the two oblique, the transversus, and tl rectus muscles. Each nerve gives off a lateral cutaneous branch : the mid-axillary line. These lateral cutaneous branches, having pierce the internal oblique, appear between the slips of the external oblique ar divide into anterior and posterior branches.

The subcostal nerve is the anterior primary division of the twelft thoracic nerve. It is in series with the eleventh intercostal, but not ranked as an intercostal nerve, inasmuch as it lies along the low* border of the twelfth rib. It is commonly spoken of as the last thorac nerve. Its abdominal relations, course, and distribution are simik to the preceding nerves, with an additional distribution to the pyram dalis abdominis. Its lateral cutaneous branch, which is undivide* having pierced the internal and external oblique muscles, descenc over the anterior part of the iliac crest 1 inch behind the anteric superior iliac spme, and is distributed to the skin of the anterior pai of the gluteal region as low as the greater trochanter of the femur; th nerve is very variable in size, and is not infrequently absent.

The ilio-hypogastric nerve, having pierced the posterior part of tb transversus abdominis a little above the iliac crest, furnishes its latere cutaneous' branch, which perforates the internal and external obliqu* and, having crossed the iliac crest at the junction of its middle an


THE ABDOMEN


7 2 9


aterior thirds, is distributed to the skin of the adjacent part of the luteal region. The nerve then continues its course forwards between re internal oblique and transversus, supplying branches to these mscles and communicating with the ilio-inguinal nerve. About inch in front of the anterior superior iliac spine it pierces the internal blique, and runs forwards between that muscle and the external blique aponeurosis. Finally, it pierces that aponeurosis about i inch bove the superficial inguinal ring, and is distributed to the skin of the iprapubic region, where

is in series with the nterior cutaneous nerves.

The ilio-inguinal nerve, s it passes forwards, lies ist above, or it may be ledial to the inner lip of, le iliac crest, beneath tie transversus muscle.

[ear the anterior part of tie iliac crest it pierces tie transversus, and here ommunicates with the nterior cutaneous branch f the ilio - hypogastric, t subsequently perforates he internal oblique, after diich it descends through he lower two-thirds of he inguinal canal, and merges through the uperficial inguinal ring,

/here it lies lateral to the permatic cord. Finally, t is distributed to the kin of the inner side of he thigh in its upper hird, and to the skin of he scrotum or labium fiajus, according to the ex. The nerve in its course supplies branches to the internal oblique nd transversus muscles. The fibres of the ilio-hypogastric and ilionguinal nerve often run for a variable distance within the same sheath.

Deep Arteries of the Abdominal Wall.— The inferior epigastric artery arises from the inner side of the external iliac, about \ inch hove the inguinal ligament. At first for a very short distance it )asses inwards between the inguinal ligament and the lower border >f the deep inguinal ring, lying in the extraperitoneal fatty tissue. It hen changes its course, and passes upwards and inwards, lying close to he inner side of the deep inguinal ring, only the external vena comes


Fig. 428. —Deep Nerves of Abdominal Wall

LYING BETWEEN TRANSVERSUS AND INTERNAL

Oblique (IO).











730


A MANUAL OF ANATOMY


intervening. On arriving at the outer border of the rectus abdomir at a point about midway between the upper border of the symphy pubis and the umbilicus, it pierces the fascia transversalis, and ascen within the sheath over the arcuate line of the sheath of the recti It then changes its course, and ascends vertically between the mus< and the posterior wall of the sheath as high as the umbilicus. Here enters the muscle, and about 2 inches above the umbilicus ends in terminal branches, which anastomose with branches of the super: epigastric artery. The inferior epigastric lies at first in the subpe toneal areolar tissue, having the parietal peritoneum on its deep surfa


P 1


Fig. 429.— Scheme of Vascular Anastomosis on the Posterior Wall

Sheath of Rectus.

and the fascia transversalis superficial to it. Shortly after passing t deep inguinal ring the vessel pierces the fascia transversalis, and in i course to the outer border of the rectus forms the outer boundary the inguinal triangle. As the vessel turns from the lower border the inner sides of the deep inguinal ring it has the spermatic cord front of it, and the vas deferens here hooks round its outer side. Ti course of the vessel in its first or oblique part is indicated by a lii drawn from the inner border of the deep inguinal ring to the out border of the rectus abdominis at a point about midway between t] umbilicus and the upper border of the symphysis pubis. The cour of the second or vertical part of the vessel is represented by a vertic


































THE ABDOMEN


73 i


ne corresponding with the centre of the rectus, and distant from the nea alba about i| inches.

Branches. —These are as follows: cremasteric, pubic, muscular, iitaneous, peritoneal, and terminal or anastomotic.

The cremasteric artery enters the spermatic cord and supplies the remaster muscle and the other coverings of the cord. It anastomoses ith the testicular artery, the superficial and deep external inferior rteries, and the superficial perineal artery. The cremasteric artery

replaced in the female by the artery of the ligamentum teres of the ter us.

The pubic artery passes inwards behind the inner half of the inuinal ligament to the back of the body of the os pubis, where it anastoloses with the pubic branch of the obturator artery and its fellow of tie opposite side.

The muscular branches arise chiefly from the outer side of the iferior epigastric, and supply the two oblique, transversus, and rectus mscles. They anastomose with the lower two posterior intercostal rteries, the subcostal artery, the abdominal branches of the lumbar rteries, and a large ascending branch of the deep circumflex iliac rtery.

The cutaneous branches perforate the rectus and the anterior wall f its sheath, to be distributed to the skin, in which they anastomose nth branches of the superficial epigastric.

The peritoneal branches pierce the posterior wall of the sheath of he rectus, to be distributed to the adjacent parietal peritoneum.

The terminal or anastomotic branches enter the rectus above the svel of the umbilicus, and anastomose with the superior epigastric of the nternal mammary.

For the abnormal obturator artery, see p. 566.

There are two venae comites with the inferior epigastric artery, one >n either side. These ultimately join to form one vessel, which erminates in the external iliac vein.

The superior epigastric artery is one of the terminal branches of the nternal mammary from the first part of the subclavian. It descends )ehind the seventh costal cartilage, passes between the sternal and

ostal portions of the diaphragm, and enters the sheath of the rectus, vhere it lies at first between the muscle and the posterior wall of its heath. It then enters the muscle and anastomoses with the inferior pigastric. Its branches are as follows: sternal , which crosses in front >f the xiphoid process and anastomoses with its fellow of the opposite 'ide; phrenic , to the diaphragm; muscular, to the muscles of the ablominal wall; anterior cutaneous, to the skin; hepatic (present only on he right side), which passes to the liver in the falciform ligament and mastomoses with the hepatic artery; and peritoneal, which pierce the posterior wall of the sheath of the rectus, to be distributed to the adjacent parietal peritoneum. The vessel is accompanied by two ^enae comites, which terminate in those of the internal mammary utery.


732


A MANUAL OF ANATOMY


The deep circumflex iliac artery arises from the outer side of 1 external iliac, nearly opposite the origin of the inferior epigastric, passes outwards and upwards behind the outer half of the ingui] ligament, where it is contained in a canal formed at the junction the fascia transversalis and fascia iliaca. Having arrived at 1 anterior superior iliac spine, it pierces the fascia transversalis, a courses outwards and backwards along the iliac crest on its ini aspect. At its termination it anastomoses with the lumbar brar of the ilio-lumbar from the internal iliac. Over about the anter half of the iliac crest the artery lies beneath the transversus muse but about the centre of the crest it pierces that muscle, and sub quently lies between it and the internal oblique.

Branches. —In the first part of its course the vessel gives branches the ilio-psoas, sartorius, and tensor fasciae latae, in which latter mus it anastomoses with the ascending branch of the external circumfl from the arteria profunda femoris. As it courses along the iliac cr< it furnishes branches to the muscles of the abdominal wall, some which reach the gluteal region, where they anastomose with the super: gluteal of the internal iliac and the superficial circumflex iliac of t femoral. It also gives branches to the iliacus muscle, which anasi mose with the iliac branch of the ilio-lumbar from the internal ill; One of the muscular branches of the artery is very constant and large size. It springs from the vessel near the anterior superior ili spine, and, having pierced the fascia transversalis and transvers muscle, it ascends vertically between that muscle and the interr oblique, where it anastomoses with the abdominal branches of t lumbar arteries. This branch is usually spoken of as the ascendi branch.

The deep circumflex iliac artery is accompanied by two vei comites. These ultimately join to form one vessel, which crosses t external iliac artery from without inwards about \ inch above t inguinal ligament, and terminates in the external iliac vein.

The lower two posterior intercostal arteries ultimately leave t tenth and eleventh intercostal spaces, and pass towards the rect muscle, lying in their course between the internal oblique and trar versus. They anastomose with the superior epigastric, inferi epigastric, and subcostal arteries.

The subcostal artery lies below the last rib, and is in series wi the posterior intercostal arteries above and the lumbar arteries bekr In the abdominal wall it anastomoses with the last intercostal, tl abdominal branch of the first lumbar, and the superior epigastr arteries.

The abdominal branches of the lumbar arteries pass forwan towards the rectus abdominis. They anastomose with the inferi< epigastric, subcostal, and ascending branch of the deep circumfk iliac.

The veins corresponding to the lower two posterior intercost: arteries terminate in the corresponding intercostal veins. The subcost;


THE ABDOMEN


733


ein of the right side terminates in the azygos vein, and that of the

ft side in the inferior vena hemiazygos. The veins accompanying re abdominal branches of the lumbar arteries terminate in the lumbar eins, which are tributaries of the inferior vena cava.

Deep Lymphatics. —The deep lymphatics of the lower part of the nterior abdominal wall accompany the inferior epigastric and deep ircumflex iliac vessels, and terminate in the external iliac glands; lose of the upper part accompany the superior epigastric artery, and irminate in the sternal glands.

The deep lymphatics of the lower part of the lateral abdominal r all accompany the abdominal branches of the lumbar arteries, and


Intercrural Saphenous Superficial X Interfoveolar

Fibres Opening Inguinal Ring Ligament


ig. 430. —Superficial and Deep Dissection of the Lower Part of the Anterior Abdominal Wall (after Cooper).

E. O.A. External Oblique Aponeurosis I.A.R. Deep Inguinal Ring

O.I.A. Obliquus Internus Abdominis S.C. Spermatic Cord

T.A. Transversus Abdominis D.E.V. Inferior Epigastric Vessels

F. T. Fascia Trans versalis X. Reflected Part of Inguinal Ligament


srminate in the lateral group of lumbar glands; those of the upper art accompany the adjacent anterior intercostal and musculo-phrenic rteries, and terminate in the sternal glands.

For the superficial lymphatics of the antero-lateral abdominal fall, see p. 712.

Fascia Transversalis. —The fascia transversalis is situated undereath the transversus abdominis muscle. It is of greatest strength ver the lower part of the abdominal wall, particularly between the )wer free border of the transversus and the inguinal ligament. When faced upwards to the costal margin it becomes very thin, and is there ontinuous with the fascia which covers the abdominal surface of the







734


A MANUAL OF ANATOMY


diaphragm. Along the linea alba it is continuous with the fascia the opposite side. In the lumbar region it is continuous with t] anterior wall of the sheath of the quadratus lumborum. In the regi< of the iliac crest it is attached to the anterior two-thirds of the ere immediately medial to its inner lip, where it meets and becomes co tinuous with the fascia iliaca, both of these fasciae being here interpos< between the transversus and iliacus muscles. The most importa: disposition of the fascia is along the line of the groin, where its attac ments are as follows: along the outer half of the inguinal ligament it firmly attached to that ligament on its deep aspect, and over th; extent it meets and is continuous with the fascia iliaca, the two fasci


Gbliquus Internus Abdominis


Transversus Abdominis-/ r

Gbliquus Externus,. Abdominis


Pectineus_—- 0


Sartorius _ Adductor Longus


Umbilicus

I


_Rectus Abdominis


— Spermatic Cord


. Suspensory Ligament of Penis


Ilio-inguinal Nerve


Fig. 431.— Dissection of the Inguinal Region.


here forming a canal, which contains the deep circumflex iliac vessels In the situation of the external iliac vessels, and as far inwards as th base of the pectineal part of inguinal ligament, it is only loosely attache< to the inguinal ligament, and is here prolonged downwards beneat] the ligament to the thigh, where it lies in front of the femoral vessels and forms the anterior wall of the femoral sheath. As the fascia i prolonged beneath the inguinal ligament it is strengthened by super added fibres, which are known as the deep femoral arch. In the regior of the pectineal part of inguinal ligament the fascia is attached in succession to the medial portion of the pectineal line behind the conjoinl tendon, and to the pubic crest. Behind the symphysis pubis the fascia

















THE ABDOMEN


735

lescends into the pelvis, and becomes continuous with the pubo-prosatic, or anterior true, ligaments of the bladder. The strongest part f the fascia transversalis, as before stated, is between the lower free •order of the transversus muscle and the inguinal ligament, this part f fhe abdominal wall being uncovered by muscular structures. It is i this situation that the fascia is pierced by the spermatic cord in he male and the ligamentum teres of the uterus in the female.

Deep Inguinal Ring. This ring is situated in the fascia transversalis t a point midway between the symphysis pubis and the anterior superior iac spine, and ^ inch above the inguinal ligament. It serves for the assage of the spermatic cord in the male and the ligamentum teres of tie uterus in the female. As viewed from the front, no opening is isible in the undissected state, because the fascia transversalis is pronged like the finger of a glove round the spermatic cord as the internal permatic fascia. When fully dissected the ring is oval, with the long xis lying vertically, in which direction it measures § inch, the transerse measurement being f inch. The inferior epigastric artery lies at


M. Oblig. Interims Transversalis Fascia Conjoint Tendon

Aponeurosis of Oblig. Ext.

Ext. Spermatic Fascia Cremasteric Fascia Int. Spermatic Fascia Spermatic Cord.

ig. 432. —Scheme to show the Composition of the Front and Back Walls of Inguinal Canal, and Derivations of Coverings of the Cord.


rst below, and then on the inner side of, the ring, the vessel being sre beneath the fascia transversalis. The interfoveolar ligament may 2 upon the inner side of, and below, the ring. In front of the ring ~ e the lower fibres of the internal oblique, and above is the lower free irder of the transversus. The fascia at the outer and lower parts the ring is stronger than elsewhere.

Inguinal Canal. —The inguinal canal is the oblique passage in the wer part of the anterior abdominal wall, which transmits the spermatic )rd or ligamentum teres of the uterus, according to the sex, and also Ie inguinal nerve in its lower two-thirds. It is situated immediately )ove the inner half of the inguinal ligament, its direction being downards, forwards, and inwards, and it is ij inches in length. The inlet > the canal is the deep inguinal ring, the outlet being the superficial guinal ring. Its component parts are a floor, a roof, an anterior wall, id a posterior wall. The floor in its upper two-thirds is formed by

meeting between the fascia transversalis and the inguinal ligament, ms portion of it presents a groove, which lodges the spermatic cord.

1 the lower third the floor is formed by the abdominal surface of the






736


A MANUAL OF ANATOMY


pectineal part of inguinal ligament along its line of junction with 1 latter. The roof is formed by the approximation of the anterior a posterior walls, separated only by the lower border of the transvers The anterior wall is formed by the following structures from bef< backwards: (i) the skin; (2) the superficial fatty and deeper me branous layers of the fascia of the anterior abdominal wall; (3) exter] oblique aponeurosis (all these four structures extending over the wh length of the anterior wall); and (4) the lower fibres of the interi oblique over the outer third. The posterior wall is formed by t following structures, in order from behind forwards: (1) the parie peritoneum; (2) subperitoneal fat; (3) fascia transversalis; (4) conjo: tendon over the inner two-thirds, and it may be the interfoveolar I4 ment over the outer third; and (5) the outer portion of the reflect part of inguinal ligament (provided that ligament is well developer which forms anteriorly the extreme inner part of this wall.

In early life the inguinal canal is very short. Indeed, at one peri of life it is non-existent, inasmuch as the deep inguinal ring in ve early life lies directly behind the superficial ring. As the pelvis, ho ever, increases in breadth, the deep ring is gradually shifted outwan and so the inguinal canal becomes formed.

The inguinal canal in the female differs from that in the male being of smaller size, and in containing the ligamentum teres of t uterus.

Inguinal Triangle (Hesselbach’s Triangle). —This triangle is situat at the lower part of the anterior abdominal wall above the inner h; of the inguinal ligament.

Boundaries — Medial .—The outer border of the rectus abdomii over about its lower 2 inches. Lateral .—The inferior epigastric vesse Inferior (base).—The inner half of the inguinal ligament. The ap corresponds with the point where the inferior epigastric vessels pa beneath the outer border of the rectus. The floor is covered over i whole extent by the fascia transversalis, superficial to which, ov the inner two-thirds, is the conjoint tendon, and over the outer thi sometimes the interfoveolar ligament. The floor is, therefore, co veniently divided into an inner two-thirds, where the conjoint tend< lies, and an outer third, where the interfoveolar ligament may 1 situated. 1 he triangle is covered superficially by the skin, both laye of the fascia of the anterior abdominal wall, and the external obliqi aponeurosis. The triangle is further crossed obliquely by a fibro cord, the obliterated hypogastric artery, which divides the triangle in median and lateral portions.

Spermatic Cord. —The spermatic cord extends from the deep i guinal ring to the upper part of the posterior border of the testis. F the first 1^ inches of its course it lies in the inguinal canal, and is direch downwards, forwards, and inwards. After passing through the supe ficial inguinal ring it enters the scrotum, in which it descends almo vertically, dhe relations of the cord in the inguinal canal will 1 understood on referring to the description of that canal. In the low


THE ABDOMEN


737


thirds of the canal it is accompanied by the ilio-inguinal nerve,

h lies to its outer side. 'he spermatic cord is composed of the following structures: the vas rens; three arteries—namely, the testicular artery, the artery of vas deferens, and the cremasteric artery; the pampiniform plexus eins; the lymphatics of the testis and epididymis; the testicular us of sympathetic nerves; and the genital branch of the genito)ral nerve. These structures are connected by areolar tissue, and

ord receives certain coverings to be presently described. 'he vas deferens is the excretory duct of the testis. It commences le tail or globus minor of the epididymis, and terminates at the


r iG. 433 - —Transverse Section of the Vas Deferens, showing its

Minute Structure.

! of the prostate gland by joining the duct of seminal vesicle to form ejaculatory duct. This latter duct, having passed between the die and lateral lobes of the prostate gland for about i inch, opens a the lateral margin of the orifice of the prostatic utricle on the ■ of the prostatic portion of the urethra. The vas deferens at its mencement is slightly tortuous, but it soon becomes straight. It at first on the inner side of the epididymis, and along the posterior ler of the testis. After entering the cord it is placed behind all the ‘r elements, where it can be readily felt and recognized from a resemice to whipcord. It maintains this position until it arrives at the ) inguinal ring, where it lies on the inner side of the other elements he cord. After passing through the deep inguinal ring it hooks

47
















738


A MANUAL OF ANATOMY


round the outer side of the inferior epigastric artery, and, having cros the external iliac vessels from without inwards, it dips down on inner side of the external iliac vein, and so enters the pelvis under co of the peritoneum, where it will be afterwards described. The deferens in its natural state measures about i foot in length, but w] straightened attains a length of about if feet.

Structure of the Vas Deferens. —The vas deferens has a very thick wall, ; feels like a piece of whip-cord. Its outer coat consists of fibrous tissue. Wit this there is a thick muscular coat composed of plain muscular tissue, wl is arranged in three layers—an outer longitudinal, a middle circular (both which are thick), and an inner thin longitudinal layer. Within the musci coat is the mucosa, which is covered by non-ciliated columnar epithelium.

Development. —The Wolffian or mesonephric duct is converted into the deferens in the male, becoming connected with the testis through some of tubules of the mesonephros. It degenerates in women.

The artery of the vas deferens is usually a branch of the super vesical of the internal iliac, though it may arise from the infer vesical; it divides into a descending and an ascending branch. 1 descending branch passes downwards to supply the lower part of 1 vas deferens and the seminal vesicle. The ascending branch acco panies the vas deferens through the inguinal canal to the testis, supp ing the vas deferens, and giving a few twigs to the tail of the epididyn in which latter situation it anastomoses with the epididymal brar of the testicular artery. The artery to the vas is sometimes of lai size, and may take the place of the testicular artery when that ves is absent.

The vein from the vas opens into the vesical plexus of veins, a thence into the internal iliac vein.

1 he testicular artery arises from the abdominal aorta about i in below the renal artery. On approaching the upper part of the tes it divides into glandular and epididymal branches, the former supplyi the testis and the latter the epididymis. As the artery descends in t spermatic cord it supplies branches to its coverings which anastomc with the cremasteric artery; its epididymal branches anastomose wi the artery of the vas.

For the cremasteric artery, see p. 731.

The testicular veins issue from the testis along its posterior bordc In the cord they form a copious plexus, called the pampiniform plexi At the deep inguinal ring two veins emerge from this plexus, whi< range themselves on either side of the testicular artery. These, as th( ascend, soon join to form one vessel, that of the right side opening in the inferior vena cava, and that of the left side into the left renal vei The veins of the pampiniform plexus have valves, but they are n< competent. There is, however, a competent valve as a rule at tl termination of each testicular vein.

The lymphatics of the testis and spermatic cord, the testicuk plexus of sympathetic nerves, and the genital branch of the genih femoral nerve will be afterwards described.


THE ABDOMEN


739


Coverings of the Spermatic Cord. —The coverings, enumerated from Tin outwards, are as follows:

1. The subperitoneal areolar tissue, which is continuous with that the abdominal wall through the deep inguinal ring.

2. The fascia transversalis, prolonged from the margins of the sp inguinal ring, and known as the internal spermatic fascia. This /ering near the ring is funnel-shaped, and is hence called the inidibuliform fascia, but lower down it becomes incorporated with j subperitoneal areolar tissue and forms the fascia propria of Cooper.

3. The cremasteric fascia.


Testicular Artery


Pampiniform Plexus of Vein.

Epididymal Branch of Testicular Artery

Glandular Branch of Testicular Artery


Appendices Testis


Artery of the Vas Deferens Vas Deferens


Pampiniform Plexus of Veins


— Sinus of Epididymis


Fig. 434. —Dissection of the Spermatic Cord, showing the Bloodvessels and Duct of the Testis (after Sappey).


4. The external spermatic fascia.

5- The dartos muscle.

6. The skin.

Within the innermost of these coverings there are a few scattered uscular fibres, which constitute the internal cremaster of Henle, and fich are regarded as representing the gubernaculum testis of the

tus. The fibres of the cremaster proper are of the striated variety, but ose of the internal cremaster are of the plain variety.

Descent of Testis and Formation of Inguinal Canal.— The testis originally s m the lumbar region of the abdomen, on the mesial side of the Wolffian body mesonephros. The conditions in the sixth week are shown in Fig. 63.











740


A MANUAL OF ANATOMY


The elongated gonad is attached to the inner side of the mesonephros by mesorchium (or mesovarium in the female). The mesonephros is attache* the dorsal wall by the mesonephric mesentery (or mesonephric ligament). M the mesonephros atrophies, the gonad has the appearance of having more di dorsal attachment, made by the combination of the original mesorchial mesonephric attachments, and this is known as the uro-genital mesentery.

Gubernaculum Testis. —Near the lower end of the mesonephros a perito fold is found at a fairly early stage, connecting the uro-genital mesentery 1 the inguinal region at a point corresponding with the site of the future deep 1 The fold is the plica gubernatrix br plica inguinalis. It is seen in Fig. 63, an a later stage and much thickened in Fig. 69.

In the female this fold, as it descends, becomes connected with the cc sponding para-mesonephric (Mullerian) duct at the level where this duct f with its fellow to form the rudiment of the uterus and vagina.

Within the plica gubernatrix fold a fibro-muscular cord is developed, 1 sisting of connective tissue and plain muscular tissue. This cord is called gubernaculum testis. Inferiorly it is attached at first to the posterior sur of the anterior abdominal wall in the inguinal region at a point correspondin


Fig. 435. —Diagram showing the Descent of the Testis. A, first stage; B, second stage; C, final stage.

1 . Testis (in Abdomen) 4. Subperitoneal Areolar Tissue

2. Primitive Peritoneum (Tunica Adnata) 5. Fascia Transversalis

3 ; Parietal Peritoneum 6. Deep Inguinal Ring

3. Processus Vaginalis 7. Integument


the situation of the future deep inguinal ring, whence it, or the greater par it, ultimately extends to the bottom of the corresponding scrotal cham Superiorly its attachment is twofold: (i) it is principally attached to the lo part of the epididymis at the junction of the tail and vas deferens. (2) A por of it ascends within the inferior testicular fold to be attached to the cai end of the testis. According to some authors, the lower part of the gubernacu' testis is reinforced by striated muscular fibres derived from the internal obli and transversus abdominis muscles. These fibres, which form the so-ca inguinal cone, are superadded to the fibro-muscular cord just referred to, wl constitutes the core of the gubernaculum. Superiorly these superadded fil from the inguinal cone are described as being attached to the testis and epididyi Inferiorly, three attachments are ascribed to them as follows: (1) the outer bw is attached to the deep aspect of the inguinal ligament near its centre; (2) middle or principal bundle accompanies the gubernaculum testis to the botl of the scrotal chamber; and (3) the inner bundle is attached to the pubic crest Two views are thus entertained regarding the structure of the gubernacu] testis. According to one view it consists solely of plain muscular tissue ; connective tissue arranged as a cord within the peritoneal fold, called the p gubernatrix or plica inguinalis. According to the other view, in addition




















THE ABDOMEN


74i


ese fibro-muscular elements, there are superadded striated muscular fibres rived from the internal oblique and transversus abdominis muscles in the form

the inguinal cone. However constituted, the gubernaculum testis soon comes a stout thick cord, the final destination of which will be presentlyerred to.

The descent, or more properly the migration, of the organ commences before the ird month of intra-uterine life, and its usual destination is the corresponding •otal chamber. The migration is accomplished in four stages —pelvic, inguinal,

raparietal, and scrotal—and throughout all these stages it follows the lead the gubernaculum, which necessarily undergoes shortening.

The pelvic stage soon brings the testis into the iliac fossa, where it lies near 3 brim of the true pelvis, having the epididymis laterally and the vas deferens idially, the latter dipping into the pelvic cavity.

The inguinal stage takes the testis to the posterior aspect of the inguinal rtion of the anterior abdominal wall at a point corresponding to the future ep inguinal ring, where it arrives about the sixth to seventh month.

Some time previous to this a path has been made for its further progress by 3 formation of the inguinal canal and scrotal cavity. In the immediate inity of the lower or inguinal end of the gubernaculum testis a peritoneal

B C

Parietal A —-^— -- N ^



Fig. 436. —Varieties of the Tunica Vaginalis.

A, normal type; B, congenital type; C, infantile type.

pression is formed, and the principal part of the inguinal end of the guberculum now slowly penetrates the Compact anterior abdominal wall in the ?uinal region, thus giving rise to the inguinal canal and inguinal rings. In sparing this path for the testis, its gubernaculum takes with it the parietal ritoneum forming the peritoneal depression just alluded to, which accord?ly constitutes a peritoneal process, called the vaginal process. This process iy be likened to the finger of a glove, being open towards the peritoneal or dominal cavity, but closed at its distal end. The principal part of the guberculum lies behind the vaginal process, which latter aids the stout gubernaculum the formation of the inguinal canal.

As the vaginal process penetrates the inguinal portion of the abdominal wall, slongates before it the several elements which compose the wall in the following ler from within outwards :

1. Extraperitoneal areolar tissue.

2. Fascia transversalis.

3. Lowermost inguinal fibres of internal oblique muscle (cremaster).

4. External oblique aponeurosis.

5- Both layers - of anterior abdominal wall fascia (dartos muscle).

6. Skin of scrotum.




742


A MANUAL OF ANATOMY


In the foregoing manner the deep inguinal ring, inguinal canal, and su ficial inguinal ring are formed by the gubernaculum testis and vaginal proc Beyond the superficial inguinal ring these two structures enter the correspon< scrotal chamber, the lower part of the vaginal process forming a serous lining it. The lower part of the gubernaculum extends lower down than the lc end of the vaginal process, and this portion is attached to the fundus of scrotal chamber.

The intraparietal stage in the migration of the testis consists in the pass of the organ through the inguinal canal. This stage commences about seventh month of intra-uterine life, and the testis follows the lead of the mi( or principal bundle of the gubernaculum testis, gliding along the posterior ’ of the vaginal process, and being post-vaginal in position.

The scrotal stage consists in the entrance of the testis into the corresponc scrotal chamber, which usually takes place about the end of the eighth mont intra-uterine life. The organ still lies behind the lower part of the vaginal proc which it invaginates from behind to form the tunica vaginalis. The middl principal bundle of the gubernaculum testis has now become very short, an ultimately represented by an indefinite fibrous bundle, spoken of as the remi of the gubernaculum, which connects the lower parts of the epididymis and te to the fundus of the scrotal chamber. The testis lies just outside the superfi ring during the ninth month, and descends to the fundus of the scrotum after bi

As the testis descends into the scrotum, the outer and inner bundles of gubernaculum testis, according to the view that there is a conus inguinalis, drawn downwards on the sides of the spermatic cord.

There are two theories regarding the migration of the testis, which may called developmental and muscular. According to the developmental the the migration is not an active process due to muscular contraction, but is brou about by developmental changes of the nature of disproportionate or unec growth, which take place in the lumbar, iliac, and inguinal regions of the tru According to the muscular theory, maintained by those who favour the existe of a conus inguinalis, the migration is brought about by muscular contractioi follows: All three bundles of the muscular inguinal cone would draw the te down to the mguino-pubic region and thereafter the middle bundle would di it down into the scrotal chamber, the outer and inner bundles being elonga downwards. The non-striated muscular fibres in the core of the gubernacul may also take part in the descent, and the descent may be aided by the ‘ reti tion of the connective tissue of the gubernacular core.

Female. The portion of the plica gubernatrix or plica inguinalis (of wh plica the embryonic inferior ovarian fold forms a part) between the caudal < of the ovary and the fusion of the para-mesonephric duct with its fellow to fc ^ if- ^h e uterus represents the ligament of the ovary; and the p

which extends from the para-mesonephric fusion through the inguinal canal the labium majus contains the ligamentum teres of the uterus, which is homologue of part of the gubernaculum testis. In other words, the entire pi gubernatrix in the male contains the gubernaculum testis; whereas in the fern it pertains to (i) the ligament of the ovary, and (2) the ligamentum teres of uterus. The urogenital mesentery of either side, which is formed by the me vanum, mesonephric mesentery, and uro-genital fold (within which latter para-mesonephric duct lies along with the mesonephric duct) becomes the cor sponding broad ligament of the uterus (see p. 101).

Metamorphosis of the Vaginal Process. —As stated, the vaginal process originally a tubular process or diverticulum of the parietal peritoneum of 1 inguinal region, resembling the finger of a glove, which precedes the descent the testis, and behind which the testis descends, following the lead of the mid' bundle of the gubernaculum testis. After the testis has reached the scro chamber it invaginates the vaginal process from behind to form the tun vaginalis, and that process now undergoes certain changes. To understa these changes, familiarity with the following facts is necessary: (1) The vagii process is closed below and open above; (2) the lumen of the process is sim]


THE ABDOMEN


743


liverticulum of the cavity of the peritoneum; (3) the part of the process related the testis is called the testicular portion ; and (4) the part in front of the spermatic rd is referred to as the funicular portion.

The changes are as follows: (1) About the period of birth the vaginal process rally becomes constricted and closed superiorly at the deep inguinal ring, d then the process is an elongated tube, closed at each end, its lumen being w shut off from the cavity of the peritoneum. (2) A few days after birth the rcess usually becomes constricted and closed a little above the testis. (3) The iicular portion of the process usually becomes impervious and converted into ibrous thread, which as a rule disappears in the course of the first month after ■th. (4) The testicular portion of the process persists as a shut serous sac, led the tunica vaginalis. Normally the persistent remains of the embryonic ginal process in the adult are (1) the testicular portion, which forms the tunica ginalis; and (2) a small nodule on the parietal peritoneum immediately behind 3 deep inguinal ring. Instead of a mere nodule, however, a slender fibrous read, called the ligamentum vaginale, may extend downwards from this part the parietal peritoneum in front of the spermatic cord as low as the superficial

uinal ring, and sometimes as low as the tunica vaginalis. In the female the vaginal process is represented by a tubular process of the ritoneum, which lies in front of the ligamentum teres of the uterus for a short stance in the inguinal canal. When this process remains open superiorly, it known as the canal of Nuck.

Abnormal Conditions of the Vaginal Process—Congenital Type. —(1) The

ginal process may remain permanently open throughout, under which circummces the cavity of the tunica vaginalis is in direct communication with the neral peritoneal cavity. (2) The vaginal process may be closed just above the nica vaginalis, but may remain as a permanently open tube above this point. Infantile or Funicular Type. —(1) The vaginal process may be closed only at its per end near the deep inguinal ring. In these cases the tunica vaginalis, stead of being limited to the region of the testis, is prolonged upwards as an ragated tube in front of the spermatic cord into the inguinal canal. (2) The ginal process may be closed above near the deep inguinal ring, and also below st above the tunica vaginalis, the portion of it intervening between these two ints remaining as an elongated tube, closed at either end, and lying in front the spermatic cord. (3) The vaginal process is sometimes closed at intervals mg the course of the spermatic cord, and when serous fluid accumulates in the tervening patent portions, the condition is known as encysted hydrocele of e cord.

Abnormal Positions of Testis. —(1) The testis may remain permanently in e abdominal cavity. (2) Its descent may be arrested in the inguinal canal, or the superficial inguinal ring. Such conditions constitute what is known as Jptor chism.

Ectopia Testis. —The testis may occupy unusual situations. (1) It may be jnd in the anterior part of the perineum. (2) It may be found on the front of e thigh in the region of the saphenous opening, in which cases it might simulate femoral hernia. (3) It may be found dorsal to the penis, in front of the symTsis pubis.

For the structure and development of the testis, see pp. 750 and 752. Extraperitoneal Tissue.—This is situated between the fascia trans:rsalis and the parietal peritoneum. Its condition is subject to uch variety, being fairly well marked in some bodies, and in others irdly perceptible. Medial to the external iliac vein at the inguinal lament it forms the femoral septum, which closes the upper end of the moral canal, and at the internal abdominal ring it is carried downirds round the spermatic cord underneath the internal spermatic ifundibuliform part) fascia.


744


A MANUAL OF ANATOMY


Parietal Peritoneum.—This is the innermost covering of the dominal wall, and it is connected with the fascia transversalis by subperitoneal areolar tissue. Behind the deep inguinal ring it forr slight projection, which in some cases enters the ring, the correspom depression on its abdominal aspect at this point being known as digital fossa. The projecting part of the parietal peritoneum co sponds with the upper end of the original processus vaginalis, and i be continued into a slender thread-like process, the obliterated upper ] of the processus vaginalis. It is here in the female that a divertici process may extend for a short distance into the inguinal canal in fi of the ligamentum teres of the uterus, forming the canal of Nuck.


Umbilicus


Intermediate Inguinal Recess


Medial Inguinal Recess

Fig. 437 -—The Folds and Recesses on the Posterior Surface of

the Anterior Abdominal Wall.


Peritoneal Folds and Inguinal Recesses.—The peritoneum lining i posterior surface of the anterior abdominal wall below the umbili< presents folds and recesses.

The folds are five in number, one being situated in the middle li and two on either side. The median fold extends from the apex the bladder to the umbilicus, and contains the urachus. It is called 1 median umbilical fold. Of the two lateral folds, the more medial c contains the obliterated hypogastric artery, and is called the late umbilical fold. It is oblique in direction, and meets the medi umbilical fold and its fellow of the opposite side at the umbilicus, corresponds to the junction of the inner two-thirds and outer thi of the inguinal triangle. The lateral of the two lateral folds is pi




THE ABDOMEN


7 45

duced by the inferior epigastric artery, and is called the fold of the inferior epigastric artery.

The inguinal recesses are six in number, three right and three left, and are called medial, intermediate, and lateral. The medial inguinal recess is situated between the median and lateral umbilical folds, and lies behind the inner two-thirds of the inguinal triangle, the conjoint tendon, and the superficial inguinal ring. The intermediate inguinal recess is situated between the lateral umbilical fold and the fold of the inferior epigastric artery, and lies behind the outer third of the inguinal triangle. The lateral inguinal recess is situated on the outer side of the fold of the inferior epigastric artery, and its lower and inner part is behind the deep inguinal ring.


Inguinal Hernia.

By an inguinal hernia is meant a protrusion of a viscus (usually bowel, or, it may be, greater omentum) from the abdominal cavity in the inguinal region. This region is predisposed to such an occurrence from the presence of the two inguinal rings and inguinal canal, and the inguinal recesses. All forms of inguinal hernia, if complete, ultimately protrude through the superficial inguinal ring, and enter the scrotum. Relatively to the inferior epigastric artery there are two varieties of inguinal hernia—namely, lateral and medial, the former leaving the abdominal cavity lateral to that vessel, and the latter escaping medial to it. Inasmuch, however, as the region inside the inferior epigastric artery—namely, the inguinal triangle—is divisible into an inner two-thirds and an outer third, there may be two forms of medial hernia. Viewing, therefore, inguinal hernia in its relation to the abdominal wall, there are three varieties—namely, lateral oblique, medial direct, and medial oblique.

Lateral Oblique Inguinal Hernia. —This variety is called lateral because the hernia, as it leaves the abdominal cavity, is lateral to the inferior epigastric artery; and oblique, from its oblique course. The course of the hernia is as follows: it enters the lateral inguinal fossa, and stretches over it the peritoneum forming that fossa. It then passes through the deep inguinal ring, and traverses the entire length of the inguinal canal, from which it emerges through the superficial inguinal ring into the scrotum, thus forming a complete lateral oblique inguinal hernia. Throughout its entire course the hernia lies in front of the spermatic cord, and its descent is arrested at the upper part of the testis, which can be felt at its lower and back part. The bowel may be arrested at any part of the inguinal canal, the hernia being then called incomplete, and forming what is known as a bubonocele. In its descent the bowel elongates and carries before it certain investments from the structures to which it is related, these investments being called the coverings of the hernia. The first covering of this form of hernia, as of the other varieties, is derived from the parietal peritoneum, the particular part being that which forms the lateral inguinal fossa, and this constitutes the sac. the other coverings are simply those of the spermatic cord, which are all superadded to the sac. F

The coverings, enumerated in order from within outwards, are as follows:

1. Parietal peritoneum, which forms the sac.

2. Extraperitoneal tissue.

3 - Fascia transversalis, from the margins of the deep inguinal ring, forming

the internal spermatic fascia.

4 - Cremasteric fascia, at the lower border of the internal oblique muscle.

5 - External spermatic fascia, from the crura of the superficial inguinal ring.

6. Dartos muscle.

7 - Skin.


746


A MANUAL OF ANATOMY


A short distance beflow the internal abdominal ring the subperitoneal fat am internal spermatic fascia become united, and are known as the fascia propria.

The sac is composed of the following parts: (i) the mouth, which is the openin by which its interior communicates with the general peritoneal cavity; (2) th neck, which is the constricted part immediately beyond the mouth; and (3) th body. The neck of the sac is on a level with the margins of the deep inguina ring, and the inferior epigastric vessels lie imrriediately on its inner side.

The seat of stricture may be (1) at the superficial inguinal ring; (2) at th lower border of the internal oblique muscle; or (3) at the neck of the sac, the las being the most common situation.

Medial Direct Inguinal Hernia. —This variety is called medial because th hernia, as it leaves the abdominal cavity, is internal to the inferior epigastrii artery; and direct, from its straight course through the abdominal parietes. Th( course of this variety is as follows: the hernia enters the medial inguinal fossa stretching over it the peritoneum forming that fossa. It then passes througl the inner two-thirds of the inguinal triangle, and so reaches directly the superficia inguinal ring without traversing the inguinal canal. Having emerged througl the superficial ring, it descends into the scrotum, thus forming a complete media direct inguinal hernia, which is in front of, and medial to, the spermatic cord It is to be noted (1) that there is no natural opening in the fascia transversali: over the inner two-thirds of the inguinal triangle, as there is external to thf inferior epigastric artery; and (2) that the conjoint tendon covers the inner two thirds of the inguinal triangle. The coverings of this variety, enumerated ir order from within outwards, are as follows:


1. Parietal peritoneum.

2. Extraperitoneal tissue.

3. Fascia transversalis.

4. Conjoint tendon.


5. Fascia triangularis.

6. External spermatic fascia.

7. Dartos muscle.

8. Skin.


If the hernia occurs suddenly, rupture of the conjoint tendon may take place, in which cases the bowel would pass through the fissure. The seat of stricture in a medial direct inguinal hernia may be (1) at the superficial inguina] ring; (2) at the fissure in the conjoint tendon, if that structure should be ruptured; or (3) at the neck of the sac. The latter situation is the most common, and it is to be noted that the inferior epigastric vessels lie on the outer side of the neck of the sac.

Medial Oblique Inguinal Hernia. —This variety is called medial because the hernia, as it leaves the abdominal cavity, is medial to the inferior epigastric artery; and oblique, because it has to descend through the lower two-thirds of the inguinal canal. The course of this variety is as follows: the hernia enters the intermediate inguinal fossa, stretching over it the peritoneum forming that fossa. It then passes through the outer third of the inguinal triangle, and descends through the lower two-thirds of the inguinal canal, from which it emerges through the supeificial inguinal ring into the scrotum, thus forming a complete medial oblique inguinal hernia. Practically the only difference between the course of a medial oblique and a lateral oblique inguinal hernia is that the lateral oblique variety enters the inguinal canal by its natural inlet—namely, the deep inguinal ring—whereas the medial oblique variety obtrudes itself into the upper part of the inguinal canal through its posterior wall. It is to be noted (1) that there is no natural opening in the fascia transversalis over the outer third of the inguinal triangle, as there is external to the inferior epigastric artery; and (2) that there is no conjoint tendon over the outer third of the inguinal triangle. The coverings of this variety, enumerated in order from within outwards, are as follows:

1. Parietal peritoneum. 5. External spermatic fascia.

2. Extraperitoneal tissue. 6. Dartos muscle.

3. Fascia transversalis. 7. Skin.

4. Cremasteric fascia.


THE ABDOMEN


747


If the coverings of a lateral oblique and a medial oblique inguinal hernia are compared with each other, it will be seen that the former has a tube of fascia

ransversalis already prepared for it—namely, the infundibuliform fascia— vhereas the latter has to elongate before it a fresh portion of fascia transversalis. [n some cases the fascia transversalis over the outer third of the inguinal triangle s covered by an expansion from the conjoint tendon, which is known as the nterfoveolar ligament. In such cases that ligament must be added as a covering )f medial oblique inguinal hernia, its position being immediately superficial to

he covering formed by the fascia transversalis. The relation of a medial oblique nguinal hernia to the spermatic cord is similar to that of a lateral oblique, and

he possible seats of stricture are also similar. The neck of the sac is the most common situation, and the inferior epigastric vessels lie immediately on its outer side. The extreme difficulty which must be experienced in diagnosing between i lateral oblique and a medial oblique hernia is explained by the fact that the former leaves the abdominal cavity immediately lateral to the inferior epigastric vessels, and the latter immediately medial to them. Hence, the practical rule followed in operating is to cut upwards and not transversely. The propriety of this rule is further enhanced if it be remembered that a lateral oblique inguinal hernia of old standing may so drag upon the deep inguinal ring as to displace it downwards and inwards to a point behind the superficial ring, and thus a hernia which is really lateral oblique may simulate one of the medial direct variety.

Varieties of Lateral Oblique Inguinal Hernia. —There are two varieties of this form of hernia, the special features of which depend upon abnormal conditions of the processus vaginalis (see p. 742). These varieties are named congenital and infantile.

Congenital Hernia. —There are two forms of congenital hernia. (1) The processus vaginalis may remain permanently open throughout, in which case the bowel descends within that process into the cavity of the tunica vaginalis at its lower extremity. The tunica vaginalis thus represents the sac of the hernia, and this form is therefore spoken of as a hernia into the tunica vaginalis. In such cases the bowel more or less completely envelops the testis. (2) The vaginal process may be shut off only just above the testis, the part above this remaining as a funicular process communicating above with the general peritoneal cavity. In such cases the bowel descends into the funicular process, which thus forms the sac of the hernia. This form is therefore spoken of as a hernia into the funicular process.

Infantile Hernia. —There are two forms of infantile hernia— infantile hernia proper and encysted hernia. In both there is a funicular process which is closed above towards the deep inguinal ring. It may also be closed below just above the testis, being thus distinct from the tunica vaginalis, or it may simply be an upward extension of the tunica vaginalis. In either case it is situated in front of the spermatic cord. In infantile hernia proper the bowel, having elongated the parietal peritoneum to form a sac, descends between the spermatic cord and the funicular process. Its importance consists in the fact that, before the bowel can be exposed in operating, three serous layers must be divided, two of these belonging to the funicular process and the other representing the wall of the hernial sac. In this form the descent of the bowel is arrested at the upper part of the testis. In encysted hernia the bowel, having elongated the parietal peritoneum to form a sac, pushes against the upper part of the funicular process so as to invaginate it in a downward direction in the form of a cup, in which the bowel, enclosed in its sac, lies. The condition of matters is therefore very much like an egg set in its cup, assuming that the top of the shell is removed, and that the wall of the cup is formed of two layers. To bring out this simile, the contents of the egg may be taken as representing the bowel, the shell of the egg being the sac of the hernia, and the assumed two layers of the wall of the cup representing the two serous layers of the doubled-down or invaginated funicular process, the cavity thus formed representing the inside of the cup. In this form, as m infantile hernia proper, three serous layers must be divided before the bowel


A MANUAL OF ANATOMY


748

is exposed in operating, two of these belonging to the invaginated funicular proc( and the other representing the wall of the hernial sac.

Umbilical Hernia. —By an umbilical hernia is meant a protrusion of bovi or of greater omentum from the abdominal cavity in the neighbourhood of t umbilicus. The protrusion rarely occurs through the umbilicus, and is me frequent above the umbilicus than below. The coverings of an umbilical herr are as follows:

1. Parietal peritoneum.

2. Extraperitoneal tissue.

3. Fascia transversalis.

4. An expansion from the decussating fibres of the aponeuroses

of the abdominal muscles of opposite sides.

5. Superficial fascia.

6. Skin.

There is no vessel liable to be injured in operating on this form of hernia, t] inferior epigastric artery being about 1^ inches from the linea alba.

The congenital form of umbilical hernia (exomphalos) consists in a protrusic of bowel or omentum through the centre of the umbilicus into the umbilical cor in which it may descend for some distance? Its possible presence will show t] propriety of carefully examining the cord before ligaturing it after birth.

The anterior abdominal wall above the umbilicus has attached 1 it posteriorly, an inch or so to the right of the middle line, an anter< posterior fold of parietal peritoneum, which represents a part of tt upper border of the falciform ligament of the liver. This fold contair at its lower margin a portion of the obliterated umbilical vein, the s( called ligamentum teres of the liver, which extends upwards from th umbilicus to the umbilical notch on the anterior border of the live: through which it passes to enter the fissure for ligamentum teres 0 the under surface of the viscus. As the round ligament ascends to tb liver the peritoneum, within which it lies, is being gradually elongate in the form of two closely applied laminae, which form a part of th falciform ligament. The apex of this ligament is therefore at th umbilicus.


The Tunica Vaginalis and Testis.

Tunica Vaginalis Testis.—This is a closed serous sac, behind whid the testis lies. It is formed by the lower part of the vaginal process or peritoneal diverticulum, which precedes the descent of the testi from the abdomen. Like all serous membranes, it is composed of tw< layers, parietal and visceral. The parietal layer is known as the tunict vaginalis scroti, from the circumstance that it lines the scrotal chambe: of its own side. It is much larger and looser than the visceral layer with which it is continuous along the posterior border of the testis and on the spermatic cord about | inch above the organ. The viscera layer closely invests the tunica albuginea of the testis, to which it is inseparably united. It also invests the epididymis except at its posterior border, where the constituents of the spermatic cord enter 01 leave the testis. Between the epididymis and the testis it forms a recess, called the sinus of epididymis (digital fossa), and it extends upwards on the spermatic cord for about \ inch above the testis,


THE ABDOMEN


749


Along the posterior border of the organ, where this layer becomes continuous with the parietal layer, there is a narrow strip which is free from serous investment. The portion of the tunica vaginalis which is related to the spermatic cord is called the funicular part. When fluid accumulates between the parietal and visceral layers, the condition is known as hydrocele of the tunica vaginalis.

Testis.—The testis is suspended obliquely by the spermatic cord in its scrotal compartment, to the bottom of which it is loosely attached by the fibrous remains of the gubernaculum testis. The left testis is a little lower than the right. The organ is oval, and compressed from side to side. Its exterior, which is smooth, is closely invested by the visceral layer of the tunica vaginalis, except where the constituents of the cord enter or leave the organ. The surfaces are lateral and medial, the former looking slightly backwards and the latter forwards. The extremities are superior and inferior, the former being inclined forwards

Spermatic Cord

Paradidymis

Parietal Layer of Tunica Vaginalis

Epididymis Sinus of Epididymis


Fig. 438.—The Testis and its Coverings.

and the latter backwards. The borders are anterior and posterior. The anterior border looks slightly downwards and outwards, and is free. The posterior border looks upwards and inwards, and is attached. The average weight of the testis is about 7 drachms.

Epididymis.—This is an elongated narrow body, composed of the convolutions of the canal of epididymis, and lying along the posterior border and adjacent portion of the lateral surface of the testis. Its upper extremity, which is above the upper end of the testis, is enlarged, and is called the head (globus major); the lower and smaller end is called the tail (globus minor); and the intervening narrow portion represents the body. The head and tail are connected to the testis by fibrous tissue, and by a reflection of the tunica vaginalis, the former being further connected to the organ by the efferent ducts. The body, except at its posterior border, is free, being separated from the testis by the sinus of epididymis. The epididymis is completely invested by the visceral layer of the tunica vaginalis except at its posterior





750


A MANUAL OF ANATOMY


border, where there is a duplicature of that membrane containin bloodvessels and attaching it to the testis.

Appendices Testis (Hydatids of Morgagni).—These are small pyramid; bodies which are situated on the anterior aspect of the head of epididym at its lower part, or on the front of the upper end of the testis belo’ the head; they vary in position, number, and size; they may be pedunci lated or sessile. They are composed of connective tissue and blooc vessels, covered by the visceral layer of the tunica vaginalis, and ai to be regarded as vestiges of the mesonephros.

Paradidymis (Organ of Giraldes).—This organ is situated on tb front of the spermatic cord, immediately above the head of epididymi: and under cover of the funicular part of the tunica vaginalis. It cor sists of a few irregular nodules of convoluted tubules, lined with ciliate columnar epithelium. These nodules are remains of the mesonephros.

Arterial Supply of the Testis and Epididymis.—The testis derive its arterial supply from the glandular branch of the testicular (whic enters the posterior border of the organ), and the epididymis derives it supply from the epididymal branch of the testicular, which vessel arise from the abdominal aorta about I inch below the renal artery. Th tail of the epididymis also receives a few twigs from the artery to th vas, which is usually a branch of the superior vesical from the interne iliac.

The veins of the testis issue at the upper part of the posterio border, and, along with those of the epididymis, enter the spermati cord, where they form the pampiniform plexus. The right testicula vein, in which the right plexus ultimately ends, opens directly into th inferior vena cava, and the left into the left renal vein.

Lymphatics.—These ascend in the spermatic cord, and accompan; the spermatic vessels as high as the aortic groups of lumbar glands i: which they terminate. On the right side the glands to which the; pass lie in front of the inferior vena cava.

Nerve-supply.—The testicular plexus of the sympathetic system which derives its fibres from the aortic and renal plexuses.

The testis is homologous to the ovary of the female (testis muliebris)

General Structure of the Testis and Epididymis. —The testis is an aggregatio; of convoluted seminiferous tubules collected into lobes, which are encased withi; a capsule called the tunica albuginea. This tunic is a dense, bluish-white, in elastic membrane, composed of bundles of fibrous tissue. Its outer surface i closely covered by the tunica vaginalis testis. Its inner surface is invested by ; copious vascular network, known as the tunica vasculosa. At the posterio border of the testis the tunica albuginea passes for a certain distance into th interior, this inflection being called the mediastinum testis. This mediastinun extends into the organ for one-fourth of its antero-posterior measurement, anc fiom its sides and anterior border a number of septa, containing plain muscula tissue, pass off, which extend in various directions as far as the inner surface o the tunica albuginea, to which they are attached. By means of these the interio of the testis is mapped out into a number of lobes, the septa which enclose then containing the branches of the testicular artery as they make their way to th' tunica vasculosa. These compartments contain the convoluted seminiferou tubules collected into bundles called the lobes of the testis, which vary in numbe from ioo to 200. Each lobe contains from two to four tubules, and is conical


THE ABDOMEN


75i


the base being directed towards the circumference of the testis and the apex towards the mediastinum. Each tubule is about 1 inch in diameter and is convoluted. When the coils are undone the tubule measures about 2 feet in length. The tubules of each lobule


Parietal Layer of Tunica Vaginalis

— Visceral Layer of Tunica Vaginalis

Tunica Albuginea Lobe of Testis


Mediastinum Testis

[.Sinus of Epididymis - - Epididymis

Testicular Artery


Vas Deferens


! Testicular Veins

« 

Artery of the Vas Deferens


Fig. 439. —Diagram showing a Transverse Section of the Testis and Scrotum.


unite into one, and the tubules of Wall 0 f Scrotum

adjacent lobules unite in turn, and so give rise to the straight tubules, each of which is about inch in diameter, and about ^ inch in length. These straight tubules enter the mediastinum, where they form by their division a network, called the rete testis. From this rete, tubules called efferent ducts proceed, which are about -fa inch in diameter, their number varying from twelve to twenty. These leave the testis at the upper part of its posterior border. For a short distance they remain straight, but they are soon thrown into convolutions, which form conical masses, called lobules of the epididymis. The length of each lobule of epididymis is about | inch, and its apex is directed towards the testis. When the convolutions are undone, the tube assumes a length of about 8 inches, its diameter gradually diminishing from about Aq inch at its commencement to about inch at its termination. The lobules open by separate orifices into the canal of the epididymis.

The epididymis consists of one tube, having a diameter of about ^ inch

in the head, where it commences in a blind extremity. In the body it diminishes a little in diameter, and in the tail it again enlarges. The tube presents a great number of convolutions, which, being folded upon themselves and connected together by loose tissue, give rise to a series of lobules. When the convolutions are undone the length of the epididymis has been variously estimated at from 12 to 20 feet. At its upper extremity it receives the lobules, and beyond the tail it terminates in the vas deferens. At the point where it terminates in the vas deferens there is . a diverticulum connected

n it, called the aberrant ductules, which extend upwards in a convoluted anner between the epididymis and the adjacent part of the vas deferens, ^e^th Grran ^ w ^ en coils are undone, is from 8 to 12 inches in


Vas Deferens

Aberrant

Ductule


Head of Epididymis


•"Lobules of Epididymis


Body of Epididymis


"Mediastinum Testis


l—Lobe of Testis


Tunica Albuginea


Tail of Epididymis

Fig. 440.—The Structure of the Testis and

Epididymis.








75 2


A MANUAL OF ANATOMY


Minute Structure. —The convoluted seminiferous tubules are composed oj hyaline basement membrane, lining which there are several layers of epithel cells, (i) The most external layer consists of cubical cells, known as the parie cells. They line the basement membrane of the tubule, and are of two kirn The majority of them give rise to the spermatozoa, and these are called 1 spermatogenic cells, or spermatogonia. Others are of a supporting nature, a are called the sustentacular cells, or cells of Sertoli, which subsequently form i columns of Sertoli. (2) The spermatogonia undergo mitotic division and gi rise to a second layer of cells, called the primary spermatocytes, or rnother-ce ,

(3) The primary spermatocytes a


undergo mitotic division, and give rise a third layer of cells, called the seconds spermatocytes, or daughter-cells. T mitosis which the primary spermatocy undergo is of the heterotypical varie and results in the chromosomes present the secondary being half the number those present in the primary spermai cytes. (4) The secondary spermatocyi also undergo mitotic division, and gi rise to a fourth layer of cells, called t spermatoblasts, or spermatids. The spermatids, having undergone considi able modifications, give rise to the spi matozoa. These spermatozoa lie wi their heads buried between the me deeply placed cells, their long tails pi jecting free into the lumen of the tubu The enlarged ends or heads of the sp< Fig. 441.— Section through Semi- matozoa, whilst they lie buried betwe niferous Tubule (Magnified), the deeper cells, are connected with t showing Various Stages of sustentacular cells of the lining epitheliu: Development of Spermatozoa. The straight tubules are composed of

S, Sertoli cell; P, interstitial cells. basement membrane lined with a sin£

layer of cubical epithelium. The tubu] of the rete testis are destitute of a basement membrane, its place being taken 1 the connective tissue of the mediastinum. The lining membrane of the tubu] consists of a single layer of cubical cells. The efferent ducts and the lobules epididymis are composed of a basement membrane, external to which there is layer of plain muscular fibres arranged in a circular manner. The lining epitt lium is of the ciliated columnar variety.

The structure of the epididymis is similar to that of the efferent ducts ai lobules.


Development of the Internal Sexual Organs.

A short account is given on p. 100 of the formation of the male and fema glands from the indifferent stage. In the testis are found medullary or sex cort composed of small epithelioid and large sex cells. Rete cords connect these wi the tubular structures of a part of the mesonephros.

Development of the Testis. —The medullary cords form cylindrical colum in which the cells slowly arrange themselves, so that lumina begin to appe in them about the seventh month. At the same time, or earlier, lumina a found in the rete cords, and by extension in each case those of the medullai and rete cords become continuous. Of the set of tubules formed in this wa those derived from the rete cords make the straight tubules and network of t] rete testis, while the larger parts, formed from the medullary cords, constitu the seminiferous tubules. The cells between the cords condense to form tl septa, continuous at the surface with the tunica albuginea. The tunica albugin is recognizable at a much earlier stage, half-way through the second monti


THE ABDOMEN


753


development at this time ensures that, from now on, no further ingrowth cells from the surface layer can take place. Here and there, between the astomosing cell cords, are certain epithelioid cells, which seem to have been t off from the neighbouring cords; these are said to develop at a late stage into e interstitial cells of the testis.

The seminiferous tubes of the growing testis of later stages are lined by several ^ers of cells, as described above. Spermatozoa remain quiescent in their sition up to the time of puberty, when, becoming motile, they free themselves d pass into the lumen, which has become considerably larger at this period. The structure and development of spermatozoa are dealt with on pp. 12 and , and the nuclear (reduction) changes on p. 17.

The convoluted canal of the epididymis, the vas deferens, and the ejaculatory ,ct are developed from the mesonephric duct. The seminal vesicle is formed rly in the fourth month as a blind diverticulum of the caudal part of the ssonephric duct, and the aberrant ductule is a slender diverticulum of that irtion of the mesonephric duct which forms the tail of the epididymis; it is remnant of the mesonephros, as is also the paradidymis at a higher level.

Development of Ovary.—Medullary cords become apparent in the ovary at much later stage than in the testis, and are not so well defined, giving the imession of being little more than rudimentary formations. The same may be id of the rete cords, which, however, seem to be better formed, and even develop mina in some cases. The rete cords effect junction with the glomerular strucres of the neighbouring part of the mesonephros, at any rate in some instances, id are said to join also with the rudimentary medullary cords, but the whole t of structures is only of temporary existence. During the third month vessels ow into the hilum of the organ, and by their extension produce the appearance of complete septa within it. About a month later cells begin to invade the gland 3m its covering ‘ peritoneal ’ cells, and this ingrowth displaces the rudimentary

ord ’ structures towards the hilum, where they ultimately break up and dis>pear. Ova are formed in the cells of the cords before the secondary ingrowth kes place from the surface, but when this occurs they degenerate, and ova e then derived from the ingrowing cells. Degeneration occurs even among ese, it being asserted, in fact, that the majority of ova degenerate after their rmation. It is not impossible that more than one invasion of cells may take ace from the surface, even during the first years of life, but nothing is certainly lown about this matter in the human subject.

In some animals the ingrowth from the surface takes place in the form of rds of celH, known as PfUiger’s cords, but this does not seem to be the case man, the appearance of such cords being produced only later by the aggredion of cells, which, being surrounded by indifferent cells as a tunic, make the -rly stages of the follicles of the ovary. Each follicle, then, contains cells derived Dm the surface, surrounded by indifferent mesodermal cells of the ovarian roma. One of the surface cells enlarges as the ovum, the rest, proliferating pidly, making the stratum granulosum and discus proligerus in which the ovum embedded, and also secreting the fluid (liquor folliculi) filling the follicle. The grounding stroma cells make the theca folliculi.

Development of the Epoophoron. —The horizontal tubule, which lies parallel the uterine tube, is a persistent part of the mesonephric duct, and represents the nal of the epididymis in the male. In some animals— e.g., the sow—the mesophric duct remains persistent, and, under the name of the duct of epoophoron drtner’s duct), can be traced from the broad ligament of the uterus along the le of that organ to the lateral wall of the vagina in its upper part, where it ^appears. In the human female it sometimes takes a similar course, and the •rtion of it on the uterine and vaginal walls is to be regarded as representing e vas deferens in the male. The transverse tubules of the epoophoron, extend? from the region of the ovary to the horizontal tubule (so-called duct of epo'horon), into which they open at right angles, are vestiges of the anterior gmental tubes of the mesonephros, and represent the straight tubules, rete dis, efferent ducts, and lobules of epididymis of the testis in the male.

48



754


A MANUAL OF ANATOMY


Development of the Paroophoron. —These vestigial tubules are derived i the more posterior segmental tubes of the mesonephros, and they represent paradidymis in the male.


ABDOMINAL CAVITY.

The abdominal cavity is somewhat ovoid, the vertical meas ment greatly exceeding the transverse. Its superior boundary formed by the diaphragm, which here presents a concave surf The inferior boundary is formed by the levatores ani and coco muscles, covered superiorly by the visceral pelvic fascia and inferr by the anal fascia. This boundary is concave on its upper asp



hie. 442 .—Diagrams to show Extent and Disposition of Abdominal Ca\ from Reconstructions in Coronal and Sagittal Planes.

D, diaphragm; LA, levator ani; A, abdominal cavity; P, pelvic cavity; FP, 1 pelvis; b, brim of pelvis, made by psoas major muscle.

I he superior and inferior boundaries, being fleshy, are capable of c tracting and relaxing alternately. During contraction the diaphra descends on each side and the levatores ani ascend, thus diminish the vertical measurement of the cavity. During relaxation the rev( takes place, the diaphragm ascending and the levatores ani descend] and so the cavity is increased in its vertical measurement, anterior and lateral boundaries are partly osseous and partly musci aponeurotic; the osseous boundaries are formed by the lower i










THE ABDOMEN


755


>ove and the pelvis below; elsewhere these boundaries are formed by le musculo-aponeurotic planes of the abdominal muscles. The )sterior boundary is formed by the bodies and discs of the lumbar irtebrae, psoas major and quadratus lumborum muscles with their Lscial investments, the sacrum and coccyx. The cavity is divided ito two regions, the abdomen proper and the pelvis. The abdomen roper is limited below by the brim of the pelvis, and its visceral con:nts are the abdominal portion of the alimentary canal, with the tception of the pelvic colon and rectum; the liver, pancreas, spleen, idneys, and suprarenal bodies. The pelvis is situated below the level [ the brim, and contains the pelvic colon, rectum, and internal uromital organs.

Abdomen Proper.

Division into Regions.—The abdomen proper is divided into nine jgions by means of two horizontal and two vertical lines, with their Drresponding planes. The horizontal lines are called subcostal and itertubercular. The subcostal line encircles the abdomen proper on level with the lowest parts of the tenth costal cartilages, and the lane corresponding to it is called the subcostal plane. The interabercular line connects the tubercles of the iliac crests, which can sually be felt about 2 \ inches behind the anterior superior iliac spine, he plane corresponding to this line is called the intertubercular plane, he vertical lines are called the lateral lines, right and left, and each xtends vertically upwards from the centre of the inguinal ligament, 'he subcostal and intertubercular lines, with their corresponding (lanes, map out the abdomen proper into three horizontal zones, ailed costal, umbilical, and hypogastric. The two lateral lines, with heir corresponding planes, subdivide each of these zones into three egionS'—two lateral, right and left, and a central. The abdomen >roper is thus eventually divided into nine regions, three in each of he three horizontal zones, as follows: the costal zone is subdivided nto right hypochondriac, epigastric, and left hypochondriac regions ; he umbilical zone is subdivided into right lumbar, umbilical, and left umbar regions ; and the hypogastric zone is subdivided into right iliac, lypogastric, and left iliac regions.

The regions just described and named are in general clinical use, md serve the purpose of allowing clinical description of location -vith great exactitude. Where more accurate placing is desirable, and n surface-marking of organs, it is customary to adopt the system ntroduced by Addison. This is a simple method, in which the whole trunk is halved and quartered horizontally, while vertical lines are only right and left lateral in addition to the median plane; here also the right and left lines are obtained by halving the distance between the tniddle line and the anterior superior iliac spine.

Fig. 443 shows Addison’s lines in position. The median plane is flanked by lateral lines, each half-way between it and the anterior superior spine. It is evident, therefore, that these lines do not corre


75 ^ A MANUAL OF ANATOMY

spond with mid-Poupart lines. The transpyloric plane (TP) is half-w between the symphysis pubis and the suprasternal notch, dividi the trunk into upper and lower halves, each of which is again bisecti The upper plane (TT) gained in this way is the transthoracic, which

not used, being put in oi to complete the system. T lower plane (IT) is t intertubercular , extending 1 tween the tuberculated pi minences on the iliac cre< it usually corresponds me or less with Cunninghan ‘ intertubercular ’ plane, b is not obtained in the sar way, and should not be co fused with it.

It may be mentioned ht that the transpyloric plane is the level of the first lumt vertebral body. For clink purposes it can be found practice by taking a level ha way between the umbilicus ai the infrasternal notch—not t xiphoid cartilage; this is only way of getting the level witho exposure, but it is not the actu transpyloric plane, which is ha! way between the symphysis ar suprasternal notch.

Superficial View of tl Contents. — On taking superficial view of the coi tents of the abdomen prop* the sharp anterior border ( the liver is seen on the rigt side projecting beyond th right costal margin, and als bulk of the organ, howevei lies concealed in the right hypochondrium, and the extent t which it passes into the left hypochondrium usually corresponds t the left mammary line. In the middle line it projects beyond th xiphoid process for about 2 inches, but along the right costal margi: it does not usually project more than about J inch. The anterio border presents two notches. One, which is well defined, is called th umbilical notch. It is situated fully i inch to the right of the middl line, and transmits the obliterated umbilical vein or ligamentum tere of liver. I he other, which is situated about 2 inches to the right of th< umbilical notch, is usually somewhat indefinite, and is called th< cystic notch. It allows the fundus of the gall-bladder to come forwarc


Fig. 443.

-Addison’s Lines on the Abdomen,

AS DESCRIBED IN TEXT.


beyond the xiphoid process. The great










THE ABDOMEN


757


posite the ninth right costal cartilage at a point coinciding with the ter border of the right rectus muscle. The falciform ligament is nspicuous as it takes attachment to the supero-anterior surface of s liver, which it divides into two lobes, right and left.

On the left side a portion of the stomach is visible, though a large rt of the viscus lies deeply in the left hypochondrium. The portion lich is seen in the epigastrium is partially covered by the left lobe of e liver, but a part of it in contact with the anterior abdominal wall, ovided the viscus is not empty. Descending from the greater curva


mall Intestine


Gall Bladder Stomach


Trans. Colon


Cosc.um


Bladder


I.iver


Fig. 444.—Anterior View of the Abdominal Viscera in situ.


ire of the stomach there is an extensive fold of peritoneum, which mgs down in the form of a curtain, and so conceals the jejunum and mm. This fold is called the greater omentum.* In normal circumances it descends as low as the level of the sacral promontory upon ie left side, but it stops a little short of that level on the right side, he condition of the greater omentum is subject to much variety. 1 some bodies it is very narrow, and much puckered in the vertical erection, so as to leave exposed the viscera which are normally covered 7 it. In other cases it is displaced to one or other side, or it may

For the distinction between an omentum, a mesentery, and a peritoneal gament, see p. 779 et seq.

















758


A MANUAL OF ANATOMY


even be raised into the left hypochondrium. In normal circumstai a few coils of the ileum are visible beyond the greater omentum on right side, and, more especially in the female, one or two loops of ileum may descend into the pelvic cavity to occupy the recto-utei In the right iliac fossa the caecum is in part seen, and in the left i fossa the iliac part of descending colon is partially visible.

When the greater omentum is raised and laid over the costal mar the coils of the jejunum and ileum come into view, occupying umbilical and hypogastric regions, and extending into the right left lumbar and iliac regions. The transverse colon is also seen cros: in an arched manner from the right to the left hypochondriac regio

Stomach.—When moderately distended, the stomach is pyrif and curved. It presents for consideration the following parts: extremities, two surfaces, two curvatures, and two orifices.


u

IE

O

H



Fig. 445. —The Stomach (External View).


Extremities.—The extremities are left and right. The left extren is known as the cardiac end or fundus. It is large and round, and for a cul-de-sac. Its direction is upwards, backwards, and to the left, c it is related to the left half of the diaphragm posteriorly and to spleen. The right extremity is known as the pyloric end. It lies neath the quadrate lobe of the liver, and is directed backwards. Ii narrow and tubular, and is continuous with the first part of the di denum. Its position is indicated superficially by a well-marked circu constriction, called the pyloric constriction, in which lies a small veir the prepyloric vein (Mayo).

Surfaces.—These are antero-superior and postero-inferior. 1 antero-superior surface is convex, and, though mainly directed 1 wards, has a slight inclination forwards. It is closely related (r) the under surface of the left lobe and frequently the quadrate lc



THE ABDOMEN


759


the liver, (2) the left half of the diaphragm, (3) the anterior abminal wall, and (4) when the viscus is empty the transverse colon, e postero-inferior surface is somewhat flat, and has a slight innation backwards.*v Its relations are as follows:

1. The diaphragm.

2. The gastric surface of the spleen.

3. Thejeft suprarenal gland.

4. The gastric area at the upper part of the front of the left kidney.

5. The antero-superior surface of the pancreas.

6. The upper surface of the transverse colon.

7. The upper surface of the transverse meso-colon.

Curvatures. —The curvatures, also known as borders, are lesser and sater. The lesser curvature, or posterior border, extends at first nost vertically downwards from the oesophagus, and then passes wards and to the right to the pyloric constriction. It is concave, d is directed backwards and towards the right. The lesser omentum nnects the lesser curvature with the lips of the porta hepatis of the er, and between the two layers of the lesser omentum, along the

ser curvature, there are the left gastric artery and the pyloric branch the hepatic artery, with the corresponding veins, and near the sophageal extremity a number of lymphatic glands. Towards its r loric extremity the lesser curvature presents a notch, which is proiced by the stomach being bent upon itself. This notch is called the igular notch. It indicates the division of the stomach into cardiac id pyloric parts, and lies in or near the middle line. The greater irvature, or anterior border, extends from the left side of the lower id of the oesophagus to the duodeno-jejunal constriction. It is con:x, and much arched. At first it arches over the fundus, passing wards, backwards, and to the left. It then passes downwards and rwards, and finally extends from left to right. The direction of the eater part of the greater curvature is forwards and towards the left.

gives attachment to the greater omentum and the gastro-splenic 'ament. The greater omentum is attached to the greater part of the eater curvature, from which it depends. Between its two layers Lere are the right gastro-epiploic artery and the left gastro-epiploic tery, together with the gastro-epiploic veins, right and left, and in ie region of the pylorus the subpyloric lymphatic glands. The gastro)lenic ligament is attached to the greater curvature to the left of the itachment of the greater omentum, one being directly continuous with ie other, both being part of the same peritoneal fold. The transverse don lies immediately below the greater curvature, under cover of ie greater omentum. About i| inches from the pyloric end the greater irvature may present a notch, called the sulcus intermedius, which idicates the subdivision of the pyloric part of the stomach into a yloric canal and a pyloric antrum; the sulcus is, however, very ininstant in position, and may be found at variable points along the neater curvature; it is not infrequently absent, and when present is nought to be the result of a transitory contraction.


760


A MANUAL OF ANATOMY


Orifices. —These are two in number—namely, cardiac and pylc The cardiac orifice is also known as the oesophageal orifice, and throi it the oesophagus opens into the stomach. It is situated at the up and left extremity of the lesser curvature, fully 2 inches to the righ the highest part of the fundus. The pyloric or duodenal orifice, throi which the stomach communicates with the duodenum, is small variable, and is situated at the right extremity of the stomach. I directed backwards, and is guarded by the pyloric sphincter, which 1 be described in connection with the structure of the stomach. Its posit is indicated superficially by the pyloric constriction already referred

Divisions of the Stomach. —The stomach is divided into two pc —cardiac and pyloric—by means of a line connecting the angular nc on the lesser curvature with the opposite point on the greater curvati The cardiac part lies to the left of this line, and is of large size, consists of the fundus and body of the stomach, the separation betw< these two parts being indicated by a line connecting the cardiac orii with the opposite point on the greater curvature. The pyloric pj which is short, is subdivided into two portions—namely, the pylc canal and the pyloric antrum—by means of the sulcus intermed on the great curvature. The pyloric canal adjoins the pyloric c< striction. It is about ij inches in length, and is narrow and cylindri in outline, like a portion of the small intestine. Its walls are thi and it is directed backwards. The pyloric antrum is a dilatation situai to the left of the pyloric canal, from which it is separated by the sul intermedins.

Position of the Stomach. —When the stomach is empty it is co paratively small, due to the contracted state of its walls during li It is situated in the left hypochondrium and the left part of the e gastrium, and is falciform in outline. The fundus is directed upwai and backwards; the cardiac portion, somewhat saccular, is direct downwards, forwards, and slightly to the right; the pyloric porti< tubular in outline, passes backwards and to the right; the pylorus 1 about \ inch to the right of the median line; the surfaces look upwai and downwards; and the greater curvature looks forwards, and t lesser curvature backwards.

When the stomach becomes distended it usually assumes an obliq position, its long axis being directed downwards, forwards and to t right.. The organ increases in length; the pylorus is carried towai the right side, assuming a position from 1J to 2 inches on the right si of the median plane; the pyloric canal is bent backwards; the fund becomes enlarged and directed upwards and towards the left; ai the upper surface acquires an inclination forwards, and the und surface an inclination backwards. The position of the cardiac orifi is practically unaltered. The stomach still occupies the left hypocho drium and the epigastrium, but, when much distended, part of may enter the umbilical and left lumbar regions. It is along t greater curvature that the main change occurs in distension; lit] alteration takes place along the lesser curvature.


THE ABDOMEN


761


Typography of the Stomach. —The cardiac orifice is situated behind he seventh left costal cartilage about an inch from the sternum. It is bout 4 inches distant from the anterior abdominal wall, and is on a 3 vel with the upper part of the body of the eleventh thoracic vertebra.

The pyloric orifice, or pylorus, is on a lower level and more anterior lane than the cardiac orifice, and, moreover, usually lies to the right f the median line. Relatively to the vertebral column it is on a level dth the upper part of the body of the first lumbar vertebra, and is pposite the tip of the ninth right costal cartilage. When the stomach 5 empty, the pylorus usually lies about J inch to the right of the median ne, but this distance is increased during distension to ij or 2 inches, r even more. The pylorus lies about 4 inches below the junction of he seventh right costal cartilage with the sternum, on a horizontal ne drawn midway between the suprasternal notch on the upper border f the manubrium sterni and the upper border of the symphysis pubis, he so-called transpyloric line (Addison). The pylorus usually lies 1 the transpyloric plane, about \ inch to the right of the middle line.

Peritoneal Relations. —The stomach is almost completely invested by perioneum, the anterior surface deriving its covering from the peritoneum of the eneral cavity, and the posterior surface from that of the lesser sac. The parts ncovered by peritoneum are as follows: a narrow line along the lesser curvature ietween the two layers of the lesser omentum for the passage of the left gastric nd pyloric vessels; a narrow line along the greater curvature between the two lyers of the greater omentum for the passage of the right and left gastro-epiploic essels; and the uncovered area or trigone. This latter area is situated on the (osterior surface below, and a little to the left of the cardiac orifice. It is about inches in breadth, and rather less from above downwards, its shape being riangular. This part of the stomach is in contact with the left crus of the iaphragm, and sometimes with the left suprarenal gland. The reflection of he peritoneum on the left of this area is carried upwards as a pointed process 0 the diaphragm, and is known as the gastro-phrenic ligament. The bare area •ermits of the passage to and from the lesser curvature of the left gastric artery nd vein.

bor the structure and development of the stomach, see pp. 856 ind 862.

Position, Connections, and Component Parts of the Intestinal Canal.—

fhe intestinal canal commences at the pyloric end of the stomach md terminates at the anus. It is divided into small intestine and large ntestine.

The small intestine commences at the pyloric extremity of the tomach, and terminates in the right iliac fossa by opening obliquely nto the large intestine. It measures in the cadaver about 23 feet n length, and is divided into three parts, which, from above downwards, ire called the duodenum (twelve fingers’ breadth), jejunum (‘ empty ’), md ileum (‘ coiled ’). In the living this measurement is reduced by 1 third, and in formalin-hardened bodies by a half. The duodenum s from 10 to 11 inches in length, and its limits are the pyloric extremity d the stomach and the duodeno-jejunal flexure on the left side of die body of the second lumbar vertebra. Since it is deeply placed, its Position and connections will be described later (p. 803). Of the


762


A MANUAL OF ANATOMY


remainder of the small intestine the upper two-fifths constitute th jejunum, and the lower three-fifths the ileum. There is no evider external mark of separation between the three divisions of the sma intestine, so that they merge imperceptibly into each other; but thei are internal characters which serve to distinguish them. On the lei side of the body of the second lumbar vertebra, where the duodenui terminates in the jejunum, the bowel describes a bend in a downwar and forward direction, called the duodeno-jejunal flexure, which i suspended from the right crus of the diaphragm by a fibro-muscula band, called the suspensory muscle of duodenum. The jejunum an ileum are very much convoluted, their coils being covered to a greate or less extent by the greater omentum. They lie below the transvers colon, and occupy the umbilical, hypogastric, right and left lumbai and right and left iliac regions. A few coils of the ileum sometime dip into the pelvis, and when this occurs they occupy, in the femak the recto-uterine pouch. The jejunum and ileum are attached to th vertebral column by a fold of peritoneum, called the mesentery propel which contains their bloodvessels, nerves, and lymphatics, and is c such a nature as to permit of great mobility in this part of the intestina tube. They are surrounded by peritoneum except along a narro\ interval corresponding with the attachment of the mesentery proper this border of the bowel being called the attached or mesenteric border as distinguished from the free or anti-mesenteric border. The sma] intestine is a smooth cylindrical tube, which gradually diminishes ii size from above downwards. The terminal portion of the ileum, a it is about to join the large intestine, is directed upwards and to th right, with a slight inclination backwards.

Diverticulum Ilei (Meckel’s Diverticulum). —This is a protrusion which i sometimes found connected with the free or anti-mesenteric border of the ileun from 1 to 10 feet above the ileo-colic valve. It represents the persistent proxima part of the vitelline or vitello-intestinal duct, which connects the yolk-sac with tha portion of the primitive alimentary canal from which the lower part of the ileun is formed. It usually measures from 2 to 3 inches in length, and its calibr generally corresponds with that of the tube from which it springs. It is ver; rarely attached to the umbilicus. In most cases it resembles the finger of ; glove, but occasionally is reduced to the condition of a cord. It is rarely provide( with a mesentery.

The large intestine commences in the right iliac fossa, and terminate: at the anus. It measures about 6 feet in length, and gradually diminishe in size from its commencement to its termination. It is composed 0 the colon and the rectum. The colon is subdivided into the caecunj (with the vermiform appendix), ascending or right colon, hepatic flexure transverse or middle colon, splenic flexure, descending colon, and pelvi colon.

Caecum.—The caecum is the commencement of the large intestine It represents that part of the gut which extends below the ileo-coli’ orifice, and is situated in the right iliac fossa, where it rests upon th ilio-psoas muscle with the intervention of the fascia iliaca. Its lowe» end or fundus has an inclination inwards towards the pelvic brim, clos




THE ABDOMEN


763


o which it usually lies. The average length of the caecum is about inches, its breadth being about 3 inches. When empty it is more or ess covered by coils of the ileum. In the distended state it comes nto contact with the anterior abdominal wall, and at the same time t descends as low as the outer half of the inguinal ligament. At its nner and back part, at a point about 2 \ inches from its lower end, it 'eceives the termination of the ileum, the opening being guarded by the ileo-colic valve. The position of this valve corresponds with a point on the right spino-umbilical line between 1^ and 2 inches from the interior superior iliac spine (McBurney’s point). In normal cases the

aecum is very movable, being completely covered by peritoneum. The

Fig. 446. —Oecum with Appendix and Terminal Piece of Ileum.

M, meso-appendix; IC, ileo-caecal fold; ICOL, ileo-colic fold.

line of reflection of the peritoneum posteriorly may correspond with the level of the ileo-colic orifice. In some cases, however, the peritoneum, after having invested the posterior aspect of the caecum, gives a covering to the posterior wall of the ascending colon for if inches (Treves), after which the reflection takes place. The line of reflection may be transverse or oblique, and the peritoneum so reflected is continuous with the left or interior layer of the mesentery proper.

In a few cases (about 6 per cent.) the upper part of the posterior surface of the caecum is destitute of peritoneum, and is bound down by connective tissue to the subjacent fascia iliaca. Under these circumstances its mobility is more or less curtailed.

The caecum is subject to much variation in its position, due, no



764


A MANUAL OF ANATOMY


doubt, to the fact that at its first appearance it lies high in the a domen to the left of the middle line. It varies both in the direction which it'descends and in the level to which it attains.

Varieties of Caecum. —The caecum is characterized by extreme variablen as regards form, but the variations may be grouped into the following th: principal types:

First Type. —d he caecum is conical, as in the foetus, the vermiform appen( springing from the apex of the cone. The three longitudinal muscular taer axe disposed as follows: one is situated on the postero-medial aspect; a seco lies along the postero-lateral aspect; and the third is placed on the anterior aspe They are nearly equally distant from each other, and meet at the junction of t caecum and vermiform appendix.

Second Type. —The caecum is divisible into two parts, an upper tubular anc lower conical, with the apex of which last part, the conus appendicis, the appenc is continuous. The taeniae are situated as in the preceding type.

Third Type. —In this variety the part of the caecum to the right of the anter: taenia becomes more developed, and consequently more prominent, than t part to the left of that band, and the anterior wall undergoes greater grow than the posterior wall. During these changes the apex is being gradua' shifted backwards and to the lefj:, until finally it takes up a position near t ileo-colic junction, where it adjoins the origin of the vermiform appendix. T part to the right of the anterior taenia becomes so much developed, especia' in a downward direction, as to give rise to a false apex. This is the most comim form of caecum, the origin of the appendix being transferred to the left ai posterior aspect.

The caecum is large in herbivora with simple stomachs— e.g., tl horse and rabbit—but small in herbivora with complicated stomachse.g., ruminants. It is usually small in carnivora— e.g., the cat—bi may be relatively large, as in the dog.

Vermiform Appendix.—The vermiform appendix is a small dive ticulum of the caecum, which opens into its inner and back part rathi more than 1 inch below the ileo-colic orifice. The caecal end of tl appendix is called its base, and the guide to it is rather more tha 1 inch below McBurney’s point. Its diameter corresponds with the of an ordinary goose-quill, and its length varies from 2 to 6 inches, ( more. Its outline is serpentine; while the lumen is originally coi tinuous along the whole length, a tendency to obliteration makes ii appearance after adult age, the apical portion being the first to I closed. The opening by which the appendix communicates with tl caecum is occasionally guarded by an indistinct fold of mucous men brane, known as the valve of Gerlach. The appendix is provided wit a mesentery, called the appendicular mesentery or meso-appendix. 1 seldom reaches more than half or two-thirds along the appendix, whic latter is thus rendered more or less convoluted or serpentine. Th meso-appendix and its variations will be found described on p. 787.

The position occupied by the appendix is extremely variable. The norm; positions may be tabulated as follows:

1. The vermiform appendix often lies under the left or inferior layer of th mesentery, where it takes a course upwards and to the left in the direction of th spleen. (According to Treves this is its usual position.)

2. It may lie on the brim of the pelvis, along the external iliac vessels, or mai project into the pelvic cavity.



THE ABDOMEN


3. It may lie to the right of the caecum and ascending colon, occupying the bTof the^ver ^° SSa an< ^ ascen ding over the right kidney towards the right

4. It may lie free among the coils of small intestine.


J ’ 447- To show the Positions and Relations to One Another of the eiver (E), Stomach (S), Gall-bladder (GB), and Colon (AC, TC, DC).

Based on the average positions of these structures given by Addison.


5; R may lie free underneath the caecum in a retro-caecal fossa. (This is the una most common situation according to Treves.)

e as :J y extend horizontally inwards to the promontory of the sacrum. 1 is x y P e ° f a PP endlx is usually only partially covered by peritoneum,

ieved to be the result of an early fixation to the abdominal wall.




j66


A MANUAL OF ANATOMY


Ascending Colon.—This extends from the caecum, on a level wil the ileo-colic orifice, to the under surface of the right lobe of tl liver at a point to the right of the gall-bladder. Here it describes bend, called the right colic flexure, which indents the liver, and «  gives rise to the colic impression. The ascending colon is aboi 5 inches in length, and occupies a part of the right iliac, right lumba and right hypochondriac regions, in which it lies deeply, being : contact with the posterior abdominal wall. Posteriorly it rests upc a portion of the right iliacus muscle covered by the fascia iliaca, tl right quadratus lumborum invested by its sheath, and the front < the right kidney in its lower and outer part. Anteriorly it is more < less covered by the coils of the jejunum and ileum, but is often : contact with the abdominal wall near its commencement. Medial it has the coils of the jejunum and ileum, and the right psoas maji muscle, covered by its fascia. The ascending colon in most cases covered by peritoneum in front and at the sides, but not behin Sometimes, however, it is completely invested by the serous membran which then forms behind it a mesentery, called the ascending mes' colon. Occasionally peritoneal folds are to be found extending fro the front of the ascending colon to the abdominal wall; one of thes more constant than the rest, is attached at, or a little above, the lev of the iliac crest, and is called the sustentaculum hepatis', it occurs about 18 per cent, of cases (Treves); it presents anteriorly a free co: cave border, and measures about ij inches in width, and about 2 inch* from before backwards.

Right Colic (Hepatic) Flexure.—This is the bend formed by tl gut between the termination of the ascending colon and the commenc ment of the transverse colon. The bend takes place in a directic forwards, downwards, and to the left, and so brings the bowel in froi of the second or vertical part of the duodenum. The right colic flexu: has the colic impression on the inferior surface of the right lobe of tl liver above it, the sharp anterior margin of the liver on its outer sid and the second part of the duodenum on its inner side. Posteriorly is in contact with the right kidney in'the same locality as the upp< part of the ascending colon, and it is here uncovered by peritoneum.

Transverse Colon.—This, which is comparatively long and vei arched, commences in the right hypochondrium in front of the secor part of the duodenum, and terminates in the left hypochondrium i the left colic flexure. Its length varies from 5 to 10 inches or mor Its extremities are deeply placed, the right being a little lower an more superficial than the left, and both being comparatively fixed c account of the shortness of the transverse meso-colon at these point The greater part of it descends into the umbilical region, where usually lies just above the umbilicus. The transverse colon is con pletely invested by peritoneum, except occasionally for 1 inch ( more posteriorly at its right extremity. The serous membrane forn an extensive fold behind it, called the transverse meso-colon, whic passes backwards to the anterior border of the pancreas, and is <


THE ABDOMEN


767

very limited extent at its right and left extremities. The transverse

olon is covered in front by the great omentum. Above it, from right to left, are the liver, gall-bladder, greater curvature of the stomach, md colic surface of the spleen; behind it are the second part of the duodenum, head of the pancreas, and transverse meso-colon; and below it are the coils of the jejunum and ileum.

Left Colic (Splenic) Flexure.— This is situated in the left hypochonirium in contact with the colic surface of the spleen, and behind the cardiac end of the stomach. It occupies a higher and deeper position Tan the right flexure, and its posterior surface is uncovered by perineum. Connected with its left aspect there is a triangular fold if the serous membrane, which attaches it to the diaphragm opposite .he tenth or eleventh left rib. This fold is called the phvenico-colic igament , it forms a platform upon which the colic surface of the spleen rests, and is hence sometimes called the sustentaculum lienis ‘ support of the spleen ’). It will be found described on p. 789.

Descending Colon. —This, which is of comparatively small calibre, Dwing to its being usually empty and contracted, commences in the eft hypochondrium at the left colic flexure, and terminates in the ower part of the left lumbar region on a level with the back part of the iliac crest, where it passes into its iliac portion. It measures about 5 inches in length, and lies deeply in the left hypochondriac and left umbar regions, being directed at first downwards and slightly inwards, md subsequently vertically downwards. Posteriorly it is in contact' rom above downwards, with the front of the left kidney at its lower and )uter part, and the left quadratus lumborum muscle invested by its Teath. Anteriorly it is covered by coils of the jejunum and ileum. Medially coils of the jejunum and ileum form a superficial relation, whilst more deeply there are the lower part of the left kidney and the eft psoas major muscle covered by its fascia. The descending colon n most cases is covered by peritoneum in front and at the sides, but lot behind. Sometimes, however, it is completely invested by the >erous membrane, which then forms behind it a mesentery, called the lescending meso-colon.

The ascending, transverse, and descending parts of the colon form m arch, within the concavity of which the coils of the jejunum and leum are disposed.

Iliac Part -of Descending Colon. —This commences on a level with -he back part of the iliac crest, and terminates at the inner border of he left psoas major anterior to the left sacro-iliac articulation. At -his point it enters the pelvic cavity and becomes the pelvic colon, d measures about 6 inches, and is situated in the left iliac fossa, where t lies upon the ilio-psoas muscle with the intervention of the fascia iaca, its direction being downwards and inwards. Anteriorly it is -overed, when empty, by coils of the ileum, but when distended it lies n contact with the anterior abdominal wall. The iliac colon in most ^ases is covered by peritoneum in front and at the sides, but not behind, sometimes, however, its terminal part is completely invested by the


A MANUAL OF ANATOMY


768

serous membrane, which then forms behind it a mesentery, called 1 iliac meso-colon.

For the pelvic colon and rectum, see pp. 943 and 944.

The large intestine, with the exception of the vermiform appenc and rectum, is characterized by well-marked sacculations, whi present a striking contrast to the smooth cylindrical contour of the w of the small intestine. These sacculations are due to the longitudii muscular fibres being largely gathered into three longitudinal ban< called tcenice coli, which are shorter than the portion of bowel to whi they are applied. The sacculations are separated from each ott by constrictions filled with fat. Another characteristic of the greal part of the large intestine is the presence at frequent intervals of sm projections of the peritoneal coat containing fat, called appendic epiploicce. These characteristics will be found described in connects with the structure of the large intestine on p. 870.

For the structure and development of the intestinal canal, s pp. 869 and 864 et seq.

Position, Connections, and Component Parts of the Spleen. —T]

spleen (lien) is a ductless gland which lies deeply in the epigastric ai left hypochondrium opposite the ninth, tenth, and eleventh rit and extending from about the level of the ninth thoracic spine to th of the eleventh. The organ can only be seen when the stomach drawn out from the left hypochondrium. It is soft, spongy, easi torn, and exceedingly vascular, and has a dark red colour. It is : liable to become enlarged that it is subject to much variety as regar< dimensions and shape. The following statement, therefore, of i dimensions is only to be accepted as approximately accurate. T 1 average length of the spleen is about 5 inches, its breadth at the wide part about 3 inches, and its thickness about ij inches. The weigh which is very variable, is about 6 ounces. The organ occupies a oblique position, its long axis being directed downwards, outwards, an forwards. Its lower two-thirds are situated in the left hypochondriun and the upper third in the epigastrium. When it has been hardene in situ its shape resembles that of an irregular tetrahedron (Cunning ham)—that is to say, it resembles a solid figure enclosed by foi equilateral triangles. The following description is based upon th view of its shape.

Apex. —This corresponds with the upper end, and lies in the ep gastrium about 2 inches from the median line. It is directed upward: inwards, and slightly forwards, and usually touches the upper laten angle of the suprarenal gland.

Surfaces. —One aspect of the organ is directed towards the dia phragm, the other looking towards the abdominal cavity and it viscera. The former aspect represents the diaphragmatic surface, whic is convex, and adapts itself to the concavity of the diaphragm. Thi surface looks outwards, backwards, and upwards. It is in contac with the diaphragm opposite the ninth, tenth, and eleventh ribs, th left plural sac containing in its upper part the thin basal margin of th


THE ABDOMEN


769


ft lung, descending for some distance between that part of the diahragm and the adjacent ribs. The visceral surface is complex, and resents three impressions, which are separated from each other by tore or less well-marked ridges, radiating from the medial colic angle Cunningham). These impressions are called gastric, renal, colic, and ancreatic.

The gastric impression is large, concave, and somewhat semilunar.

looks forwards, inwards, and downwards, and accurately adapts self to the fundus of the stomach on its posterior aspect. It is limited nteriorly by the sharp nterior border of the deen, which separates it om the diaphragmatic irface, and posteriorly it separated from the renal npression by the interlediate border, which xtends from the medial olic angle upwards to the pex. A little in front of lis border, and therefore tuated on the gastric npression, there is a ssure, called the hilum,

)r the passage of the Dlenic vessels, lymphacs, and nerves. Instead f a hilum there is somemes a row of foramina, he narrow portion of the astric impression behind he hilum is, at its lower ad, in contact with the ail of the pancreas, thus laking the pancreatic npression.

The renal impression, which is posterior to the gastric impression, s narrow. It looks inwards and downwards, and is in contact with he front of the left kidney at its upper and outer part close to the iteral border. It is separated from the gastric impression by the itermediate border, and is limited behind by the posterior border, diich separates it from the diaphragmatic surface. Inferiorly it is sparated from the colic impression by the ridge which extends from he medial colic angle to the posterior angle.

The colic impression is the small triangular surface which looks -ownwards and inwards. It rests upon the left flexure of the colon nd upper surface of the sustentaculum lienis or peritoneal platform ormed by the phrenico-colic ligament. It is separated from the renal

49


C —

Fig. 448.—Visceral Surfaces of Spleen. R, renal; G, gastric; C, colic.



770


A MANUAL OF ANATOMY


impression by the ridge already referred to, and from the gastric ir pression by the ridge which passes between the medial and anterior col angles. The angles of this impression are called medial, posterior, ar anterior, the last being the most prominent.

Borders. —These are anterior, posterior, intermediate, and inferic The anterior border is situated between the diaphragmatic surfa< and the gastric impression. It is sharp, and usually presents sever notches which are of considerable diagnostic importance. The poster! border is situated between the diaphragmatic surface and the ren impression. It is blunt, and its position and direction practical


8tb Costal Cart.


Fig. 449.— Transverse Section at the Level of the Twelfth Thoraci

Vertebra (after Symington).


coincide with the lowest left intercostal space. The intermediai border extends from the medial colic angle to the apex, and interven* between the gastric and renal impressions. The inferior bord< separates the diaphragmatic surface and the colic impression, and somewhat sharp.

The most fixed part of the spleen is naturally in the region of tl hilum. When the spleen enlarges it does so in a forward, downwan and inward direction, moving in a circumferential manner round i 1 most fixed point. The spleen moves in respiration, but cannot t palpated unless it is enlarged.



















THE ABDOMEN


771


Peritoneal Relations.—The spleen is surrounded by peritoneum, xcept at the hilum and where the gastro-splenic and phrenico-splenic igaments are connected with it. The serous membrane forms three olds, called gastro-splenic ligament, lieno-renal ligament, and phrenicoplenic ligament. The gastro-splenic ligament (omentum) is attached y one extremity to the gastric impression of the spleen just in front f the hilum, the other extremity being connected with the cardiac end f the stomach on its posterior aspect and the left border of the greater mentum. The lieno-renal ligament is attached by one extremity to the astric impression along the line of the hilum, the other extremity being ttached to the front of the left kidney at its upper and outer part, he phrenico-splenic or lieno-phrenic ligament extends between the pleen near its upper extremity and the contiguous part of the diahragm. The lieno-renal and phrenico-splenic ligaments are the )wer and upper parts respectively of one peritoneal fold.

Occasionally small accessory spleens, varying in number from one to twenty, re found in the gastro-splenic ligament in the neighbourhood of the hilum, r more rarely in the greater omentum or transverse meso-colon, rarely embedded 1 the pancreas.

Area of Splenic Dulness.—This area is limited posteriorly by the lid-scapular line between the ninth and eleventh left ribs, and anteriorly y the mid-axillary line as it crosses the ninth, tenth, and eleventh jbs, or by a line connecting the left sterno-clavicular joint with the ip of the eleventh left rib. The length of the area is about 3 inches, nd its breadth from 2 to 2\ inches.

For the structure and development of the spleen, see p. 897.

Position, Connections, and Component Parts of the Liver.—The liver lepar), which is the largest gland in the body, occupies almost all the ght hypochondrium, a great part of the epigastrium, and frequently mall parts of the right lumbar region and left hypochondrium. It is laintained in position by the following peritoneal ligaments: the oronary ligament, the right and left triangular ligaments, and the ilciform ligament.

Topography.—The size of the liver is so variable that the following tatement of its limits is only to be regarded as approximately accurate, a the right mammary line it extends from the fifth to the tenth rib lclusive. In the mid-axillary line the right aspect of the organ extends 'om the seventh to the eleventh rib, and in the scapular line its superior nd inferior limits are on a level with the ninth and eleventh thoracic 3 inous processes respectively, the ribs to which it is here related being ie ninth, tenth, and eleventh. The left limit of the organ usually correponds to the left lateral plane. In mapping out the upper limit the addle line may be taken as the starting-point. In this situation the nut is indicated by a line crossing the sternum at the level of the sixth ^stal cartilages, this line being slightly arched downwards. The line iould then be prolonged to the left, with a slight curve upwards, to point about 2 inches to the left of the left border of the sternum nd about 1 inch below the nipple. In continuing the line to the right


772


A MANUAL OF ANATOMY


it should be carried upwards so as to reach a point about \ inch belo the right nipple. The line, on being prolonged from this point towan the right side, must be carried slightly downwards so as to reach tl mid-axillary line at the level of the seventh right rib. The lower lim of the organ extends from a point about | inch below the tip of tl bony part of the tenth right rib to the left extremity of the line ii dicating the upper limit. The direction of the line indicating tl lower limit is upwards and to the left.

The liver is thus to a very large extent under cover of the low< ribs and costal cartilages of the right side, the xiphoid process, an the sixth, seventh, and eighth costal cartilages of the left side. It accurately moulded on the under surface of the diaphragm, whic separates it from the base of the right lung covered by pleura, and tl heart enclosed in the pericardium. The thin marginal part of the baj of the right lung, with its pleural investment, descends in the anguk interval between the diaphragm and the thoracic wall, and so partial] covers the liver, a relation which has to be borne in mind in percussir the organ. In the right mammary line the lung descends as low c the sixth rib, whilst the liver ascends to the upper border of the fiftt In the right mid-axillary line the lung descends as low as the eighi rib, whilst the liver ascends as high as the seventh. In the rigl scapular line (inferior angle of scapula) the lung descends as low c the tenth rib, whilst the liver ascends as high as the ninth. The live comes nearest to the surface below the right costal margin and belo^ the ensiform process. In the former situation it projects about J incl and in the latter about 2 inches, and in each situation is in contac with the anterior abdominal parietes.

Aarious circumstances affect the position of the liver. During respiratic the liver descends in inspiration and ascends in expiration. In the horizont; posture it ascends, and in the sitting or upright posture it descends. In di tension of the stomach and intestines, as well as in ascites, it ascends. In rigl hydro-thorax, hypertrophy of the heart, and hydro-pericardium it descend Long-continued pressure, as in tight lacing, causes the liver to be displaced dowi wards. Finally, when the abdomen proper is encroached upon by the gravi uterus or by an ovarian tumour the liver is displaced upwards.

The liver has a reddish-brown colour, and presents for the mos part a smooth surface. It is firm to the touch, but under pressure i friable—that is to say, easily crumbled. The dimensions of the orga can only be stated approximately. In the transverse direction (fror right to left) it measures from 7 to 10 inches, the measurement fror before backwards at its right extremity being about 6 inches, whic. also represents its vertical measurement at the thickest part of th right lobe. Its weight in the adult ranges from 45 to 60 ounces, c from 3 to 4 pounds, the weight in the female being rather less, and it relation to the body weight being in the proportion of one to forty i the adult. In early life the liver is proportionately larger than in th adult, and in a child at the period of birth its relation to the bod weight is as one to twenty.


THE ABDOMEN


773


Surfaces.—These are superior, anterior, inferior, right, and posterior, 't is not to be supposed, however, that these surfaces are all clearly eparated from one another by well-defined borders, only one margin )eing in reality distinct—namely, the anterior border, which has a rery sharp outline.

The superior surface is markedly convex in its right portion, and .ccurately adapts itself to the concavity of the diaphragm, with which it 5 in contact. To the left of this convex part there is a depression, called he cardiac impression, produced by the heart with the intervention of he diaphragm. To the left of this impression the superior surface igain becomes convex, and adapts itself to the concavity of the left lalf of the diaphragm. The superior surface is separated from the >osterior, anterior, and right surfaces by round, somewhat indistinct >orders.


The anterior surface looks forwards and is triangular. The apex s directed towards the left extremity of the liver, whilst the base is owards the right extremity. One side of the triangle corresponds to he anterior border, the other side being formed by the round border vdiich separates the anterior from the superior surface. The anterior urface is mainly in contact with the diaphragm and the right and eft costal margins, but at the middle line it is in relation with the dphoid process, and for about 2 inches below that process it is in contact with the anterior abdominal wall. The superior and anterior urfaces are divided into two lateral parts by the falciform ligament, he part to the right of this ligament being called the right lobe, and the >art to the left the left lobe. The right lobe forms about four-fifths f the entire supero-anterior surface in the adult, but in early life the wo lobes are very nearly of equal size.

The inferior or visceral surface looks downwards with an inclination





774


A MANUAL OF ANATOMY


to the left. It is divided into two parts, right and left, by the fiss for ligamentum teres. The part to the left of this fissure represenl portion of the left lobe. It lies in front of the cardiac orifice of stomach, the anterior surface of that organ close to the lesser curvati and the lower part of the lesser omentum. The part related to stomach presents an area called the gastric impression. The pari the right of this impression, close to the back part of the fissure ligamentum teres, presents a smooth round eminence, called the tu omentale. This eminence projects in a backward direction over lesser curvature of the stomach, and so abuts against the antei layer of the lesser omentum. The part of the inferior surface to


Inferior Vena Cava Caudate Process


- Cys Du<


Portal Vein


Rena

Impress


Gastric Impression on Left Lobe

/

/ /

Tuber Omentale ! i Hepatic Artery' / Common Hepatic Duct


• 1 Gall-bladder

! Quadrate Lobe


Caudate Lobe

Fissure for Ligamentum Venosum CEsophageal Impressior


Suprarenal Impression i Bare Area of Right Lobe


Duodenal Impre


Colic Impression


Ligamentum Teres Bile Duct


Fig. 451. —The Inferior Surface of the Liver.


right of the fissure for ligamentum teres presents, as its most strik] object, the gall-bladder, which occupies the fossa for gall-bladd This fossa extends from the anterior border of the porta hepatis. has the quadrate lobe on its left side, and a large part of the right lc on its right side. The portion of the inferior surface of the right lc to the left of the gall-bladder includes the following parts: the quadn lobe, the porta hepatis, the caudate process, and the lower margin the caudate lobe.

The quadrate lobe , which is elongated from before backwards, bounded anteriorly by the anterior border of the liver; posterio: by the porta hepatis; on the right side by the gall-bladder and fossa; and on the left by the fissure for ligamentum teres. It is

itact with the pyloric end of the stomach and first part of the )denum.

The porta hepatis forms a right angle with the back part of the ,ure for ligamentum teres, from which it extends over the inferior face of the right lobe for a distance of about 2 inches. It is mded in front by the quadrate lobe, and behind by the caudate )cess and the lower margin of the caudate lobe. The two layers of the ser omentum are attached to its anterior and posterior lips. It ves for the passage of the following structures, in order from before

kwards: (1) the common hepatic duct; (2) the hepatic artery, accomaied by the hepatic sympathetic plexus of nerves and lymphatic ssels; and (3) the portal vein, all surrounded by the capsule of liver. The caudate process is the narrow portion of liver substance which meets the right extremity of the lower margin of the caudate lobe th the adjacent part of the inferior surface of the right lobe. It 5 behind the porta hepatis, and has the portal vein in front of it, d the inferior vena cava behind it. It forms the upper boundary the opening into lesser sac.

The lower margin of the caudate lobe , like the caudate process, is uated behind the porta hepatis. It is divided by a notch into two linences of unequal size. The right eminence, which is the smaller the two, is continuous with the caudate process. The left eminence of large size, and is known as the papillary process. The part of e inferior surface of the right lobe which lies to the right of the gallidder is of large extent, and presents three impressions—namely, lie impression, renal impression, and duodenal impression. The lie impression , which looks downwards, is situated in front, where it s to the right side of the body of the gall-bladder. It is in contact th the right flexure of the colon. The renal impression , which is of rge size, looks backwards as well as downwards, is posterior to the lie impression, and is in contact with a large part of the front of e right kidney. The duodenal impression is situated on the inner le of the renal impression, just lateral to the neck of the gall-bladder, is in contact with the commencement of the second part of the lodenum.

The fissure for ligamentum teres is so named because it contains the mains of the umbilical vein, now known as the ligamentum teres of the >er. It commences at the anterior border of the organ in the interlobar )tch, and extends as far back as the left extremity of the porta hepatis, ith which it forms a right angle. It separates the quadrate lobe om the inferior surface of the left lobe. Sometimes the porta is more ' less completely bridged over by a portion of hepatic substance, which ms forms a pons hepatis. The obliterated umbilical vein terminates y joining the left division of the portal vein opposite the point at hich the obliterated ductus venosus, with which in the foetus the mbilical vein was continuous, is attached.

The right surface is convex, and is in contact with the diaphragm id right ribs from the seventh to the eleventh, the margin of the base of the right lung and pleura here descending between the ribs and diaphragm as low as the eighth rib. There is no well-marked line demarcation between this surface and the posterior, superior, ; anterior surfaces, but it is distinctly separated from the inferior suri by the right portion of the anterior border.

The posterior surface presents a concavity corresponding with convexity of the bodies of the tenth and eleventh thoracic vertet It is related to the diaphragm, and its component parts from left right are as follows: the posterior part of the left lobe; the oesopha^ impression; the fissure for ligamentum venosum; caudate lobe, exc


Fig. 452. —Posterior Aspect of Liver, showing Bare Area.

FL, falciform ligament; RLL, LLL, right and left triangular ligaments.


its lower margin; the fossa for the inferior vena cava; and the b; area of the right lobe.

The posterior part of the left lobe at its left extremity is a mi margin overlying the fundus of the stomach, but elsewhere it presei a distinct surface marked by the oesophageal impression, which is contact with the right side of the lower end of the oesophagus.

The fissure for ligamentum venosum lies vertically on the poster surface, having the caudate lobe on its right, and the oesophageal groc on the left lobe on its left. Interiorly it meets the left extremity of i porta hepatis and the posterior extremity of the fissure for ligament! teres, and superiorly it passes to the right and meets the fossa 1 inferior vena cava. It lodges the ligamentum venosum, which is connected below with the left division of the portal vein, and above with e inferior vena cava. The fissures for the ligamenta venosum et teres parate the right and left lobes on the posterior and inferior surfaces spectively.

Caudate lobe ( Spieghel’s lobe), with the exception of its lower margin,

s vertically on the posterior surface. It is bounded on the right side j the fossa for vena cava, on the left by the fissure for ligamentum rnosum, and interiorly by the porta hepatis. It looks backwards and little inwards, and is in contact with the right crus of the diaphragm >posite the tenth and eleventh thoracic vertebrae. Its lower margin is been already described (p. 775). The lobe lies in front of the upper id of the lesser sac of the peritoneum.

The fossa for vena cava lodges a part of the inferior vena cava. It

s vertically, and somewhat deeply, on the posterior surface, having le bare area of the right lobe on its right side, caudate lobe on its left de, and the caudate process below. This fossa is sometimes bridged rei by a portion of liver substance, called a pons hepatis. At the upper irt of this fossa the hepatic veins open into the inferior vena cava.

The bare area of the right lobe represents its back part. It measures om 2\ to 3 inches in the transverse direction, and fully 2 inches from Dove downwards, except at the extreme right, where it tapers to a Dint. It is destitute of peritoneum, and is enclosed between, the two rous layers which form the coronary ligament, being attached to the aphragm by areolar tissue. Its direction is backwards and a little wards. The extreme left end of this area, at a point immediately > the right of the lower end of the fossa for vena cava and near the tudate process, presents a somewhat triangular impression, called the iprarenal impression, for the right suprarenal body.

Borders. —The chief borders are three in number—namely, posterolperior, postero-inferior, and inferior. The postero-superior and istero-inferior borders give attachment to the two layers of peritoneum hich form the coronary ligament, and they enclose between them the Dsterior surface. The inferior border is sharp. At its right extremity passes backwards so as to separate the inferior from the right surface, t its left extremity it also passes backwards, and so forms the thin ft margin of the left lobe. Its anterior portion presents two notches, iterlobar and cystic. The interlobar notch is situated fully i inch to ie right of the middle line, and transmits the ligamentum teres. The >stic notch, often hardly perceptible, is situated about 2 inches to the ght of the interlobar notch, and allows the fundus of the gall-bladder ) come into contact with the anterior abdominal wall.

Peritoneal Relations. —The liver is covered by peritoneum except i the following regions: the bare area of the right lobe; a small triAguiar area at the posterior extremity of the hepatic attachment of ie falciform ligament; the porta hepatis; and the fossa for gall-bladder, ^cept in those rare cases in which the gall-bladder is completely inested by peritoneum.

For the ligaments of the liver, see p. 788.


Excretory Apparatus of the Liver. —This consists of the hep

ducts, the gall-bladder, the cystic duct, and the bile-duct.

The common hepatic duct is formed by the union of a right and branch which issue from the respective lobes at the porta hepatis. is the most anterior of the structures in the porta, and after a vark course of i to 3 inches downwards and to the right, it joins the cy duct, and so gives rise to the bile-duct. The diameter of the comr hepatic duct is about inch.

The gall-bladder is a reservoir for the bile. It is pyriform, an situated obliquely on the inferior surface of the right lobe, when

occupies the fossa for gall-blad< having the quadrate lobe on its side, and a large part of the ri lobe on its right side. It exte from the anterior border of the li to near the porta hepatis, and \ sents a fundus, body, and ne The fundus , which is round, lo downwards, forwards, and to right. It occupies the cystic no on the anterior border, and is contact with the anterior abdomi wall opposite the ninth right cos cartilage at the outer border of right rectus abdominis muscle. 1 body is directed upwards, ba ? wards, and to the left. Its infer and lateral surfaces are free, 1 superiorly it is attached by areo tissue to the fossa for gall-bladd IG - 453 - - Ducts » etc., J4 rests in front upon the right e

~ „ ,. ., ^ „ of the transverse colon, and behi

dt h mm™, w : 7 s ‘f on the first P art of the duodem

B, bile-duct; P, pancreatic duct; near lts junction with the stoma< A, ampulla in duodenal wall into The neck describes a sigmoid cui which both ducts open. first to the left, then to the rig'

and finally again to the left to 1 come continuous with the cystic duct. The gall-bladder is usua covered by peritoneum, except on its upper surface. Sometimes, ho ever, the serous membrane entirely surrounds it and forms a li£ mentous fold above it, by which it is loosely and movably suspend from its fossa. The gall-bladder measures about 3 inches in length, breadth at the widest part being i|- inches. Its capacity is from 1 iJ ounces. For the structure of the gall-bladder, see p. 890.

The cystic duct is 2 inches or more long, its diameter being abo j2 inch. Its course is backwards, downwards, and to the left, a: it ends by joining common hepatic duct an inch or less above t duodenum to form the bile-duct. For some distance the cystic aj


)mmon hepatic ducts run parallel and in close contact with each

her. The bile-duct (ductus communis choledochus) is formed by the lion of the common hepatic and cystic ducts. Its length varies xording to the level at which the cystic and common hepatic ducts rite, from i to 3 inches, its diameter being about J inch. It lies bereen the two layers of the lesser omentum in front of the opening into sser sac, where it has the hepatic artery on its left side arid the portal fin behind. It afterwards descends behind the first part of the duomum, and subsequently between the second part of the duodenum and le head of the pancreas. It next enters the wall of the second part “ the duodenum in company with the duct of the pancreas, and runs fiiquely in the wall for § inch. It then joins the pancreatic duct, the suiting duct forming a dilatation, called the ampulla , which, having mome constricted, pierces the mucous membrane and opens on the >p of a papilla at the junction of the inner and posterior walls of the cond part of the duodenum, where the upper two-thirds and lower rird of that part meet. The distance of this opening from the pylorus

about 3! to 4 inches. The bile-duct sometimes opens into the lodenum independently of the pancreatic duct, but close to it.

It is in the ampulla that a gall-stone frequently becomes lodged and fiayed in its downward progress towards the duodenum.

The size of the liver in early life is much greater than in the adult, the left be in particular assuming large dimensions and reaching to the spleen. As r ,e advances, however, the left lobe undergoes a marked diminution in size.

In the rabbit the openings of the two ducts are usually far apart; they are so separate but close together in ornithorhynchus, the pancreatic duct opening )ove the bile-duct.

Accessory bile-ducts are not uncommon in man; they are found leaving the rer at the extreme right end of the porta hepatis, and may join the right hepatic ict, the common hepatic duct, or the bile-duct.

For the structure and development of the liver, see pp. 884 and 888.

Peritoneum. —The peritoneum is the serous membrane which lines ie abdominal parietes, and invests more or less completely most of ie viscera. It is composed of two layers, parietal and visceral, the mtiguous surfaces of which are smooth and moist. In the male the terval between the two layers forms a closed sac, but in the female,

■ the fimbriated extremity of each uterine tube, the sac communicates ith the lumen of that tube, and through it with the cavity of the uterus id the vagina. It is at the margin of the fimbriated extremity of ich uterine tube that the endothelium of the peritoneum undergoes

sudden transition into the columnar ciliated epithelium of the uterine ibe.

The peritoneum forms certain reflections or folds which are of iree kinds—namely, omenta, mesenteries, and ligaments.

An omentum is a particular fold of peritoneum passing between the omach and another abdominal viscus. The omenta are two in number -namely, the greater omentum, which passes between the greater curvature of the stomach and the transverse colon; the lesser oi turn, which passes between the lesser curvature of the stomach anc porta hepatis of the liver.

A mesentery is a fold of peritoneum passing between a portio intestine and the posterior abdominal wall. The mesenteries in adult are normally as follows: the mesentery proper, which com the jejunum and ileum to the vertebral column; the appendic mesentery or meso-appendix, which is connected with the ve form appendix; the transverse meso-colon, which extends beU the transverse colon and the posterior wall of the abdomen at anterior border of the pancreas; and the pelvic meso-colon, w connects the pelvic colon to the anterior surface of the sacrun low as the third sacral vertebra. Occasionally the ascending cc descending colon, and iliac colon are each provided with a mesent called respectively the ascending meso-colon, descending meso-cc and iliac meso-colon.

A ligament is a fold of peritoneum which connects a viscus not of the alimentary canal to the abdominal or pelvic parietes or vis of any kind to each other or to the diaphragm. The peritoneal ligam are as follows: (1) the ligaments of the liver—namely, the falcif ligament, the coronary ligament, and the right and the left triang ligaments; (2) the gastro-phrenic ligament; (3) the gastro-splenic J ment; (4) the lieno-phrenic ligament; (5) the false ligaments of urinary bladder—namely, two posterior, two lateral, and superior; (6) the broad ligaments of the uterus.

Course of the Peritoneum. —The parietal and visceral layers of peritoneum are in unbroken continuity with each other, and this < tinuity is shown by tracing the membrane in the vertical and transv directions.

Vertical Course. —Commencing at the porta hepatis of the liver, layers of peritoneum descend to the lesser curvature of the stom; forming the lesser omentum. On reaching the lesser curvature ti two layers separate, one passing over the anterior surface and other over the posterior surface of the stomach. At the greater cui ture they come together, and descend in the form of a curtain over coils of the jejunum and ileum to the lower part of the abdomen, torn the two anterior or descending layers of the greater omentum. Tl two layers are then folded backwards, and ascend to the transvi colon, thus forming the two posterior or ascending layers of the gre; omentum. On reaching the transverse colon they separate, one la passing in front of and above the bowel, and the other layer be and behind it. Having enclosed the transverse colon, the two la] meet, and are prolonged backwards to the posterior wall of the abdor at the anterior border of the pancreas, thus forming the transv( meso-colon. On reaching the anterior border of the pancreas the 1 layers of the transverse meso-colon take leave of each other, and f( an ascending and a descending layer. The ascending layer pa: upwards over the anterior surface of the pancreas, and the poste.

tion of the under surface of the diaphragm, from which it passes the postero-inferior border of the liver, thus forming the inferior sr of the coronary ligament. Having covered the caudate lobe, it ves at the posterior lip of the porta hepatis, where it is continuous h the posterior layer of the lesser omentum.

The descending layer of the transverse meso-colon passes at first kwards upon the inferior surface of the pancreas, and then downds over the third part of the duodenum, at the lower border of



Fig. 454.— Diagram of the Peritoneum in the Adult Male (Vertical Section).

S. Stomach S.I. Small Intestine

P. Pancreas B. Urinary Bladder

D. Duodenum R. Rectum

T.C. Transverse Colon

The arrow is through the Opening into Lesser Sac.

Hi it is conducted off to the jejunum and ileum by the superior senteric vessels. Having surrounded these portions of the small -Stine, it passes to the posterior abdominal wall upon the other ect °f the superior mesenteric vessels, and so forms the mesentery P er - ^ then descends over the abdominal aorta and inferior vena a mto the pelvis, where its course will be subsequently traced. )m H le apex of the urinary bladder this layer of the peritoneum is ected on to the posterior surface of the anterior abdominal wall, -r lining which it passes to the anterior portion of the under surface


of the diaphragm, whence it is reflected on to the postero-supe border of the liver, thus forming the superior layer of the coron ligament. It then passes over the superior and anterior surfaces of liver, and, turning round its anterior border, it arrives at the ante lip of the porta hepatis, where it is continuous with the anterior la of the lesser omentum.

Transverse Course. —The peritoneum may be traced in the tn verse direction at two levels—namely, (1) above the transverse co]

or at the level of the op


ing into lesser sac, whicl situated behind the right free border, of the les omentum; and (2) below transverse colon, or at level of the umbilicus.

Above the Transvt Colon, or at the Level of Opening into Lesser Sac In front of the opening i: lesser sac there are the i layers of peritoneum, ante] and posterior, which fc the right or free border the lesser omentum, a which contain between th the bile-duct, the heps artery, and the portal ve Tracing the lesser oment' from this point to the 1< its two layers separate enclose the stomach, af


Fig. 455. —Scheme of a Horizontal Section which they pass to the gast across the Spleen, to show its Relation impression on the spleen to the Peritoneal Sacs. the gastro-splenic ligame

The cavity of the lesser sac is marked in solid The twn layers of this ll| black. S, stomach; K, kidney; D, diaphragm. t arp flnfpr i nr ~ nr i n Spleen is stippled. The dorsal meso-gaster, are anterior ana p

separating the two peritoneal sacs, is made tenor, and they contain I up of (A) the gastro-splenic ligament, and tween them the short gast (B) the lieno-renal ligament. branches of the splenic arte

At the spleen the two lay are immediately in front of the hilum. The anterior layer now tal temporary leave of the posterior layer, and turns completely round t spleen, covering its gastric, colic, diaphragmatic, and renal surfaces succession. On leaving the renal surface of the organ it again pasi to the gastric surface, but it is now behind the hilum. Here it me< the posterior layer of the gastro-splenic ligament, which had remain meanwhile stationary immediately in front of the hilum. These b layers now pass backwards to the anterior surface of the left kidney its upper extremity, and close to its lateral border, thus forming the no-renal ligament. The two layers of this ligament are disposed as 'ht and left, and between them are the splenic branches of the splenic tery. The right layer corresponds with the posterior layer of the stro-splenic ligament, and the left layer with the anterior layer of at ligament. The right layer of the lieno-renal ligament, after


Fm. 456 .— Lines of Reflection of Peritoneum from the Posterior Abdominal Wall (from a Reconstruction).

The arrow passes through the opening into lesser sac.

ving the left kidney, passes to the right over the aorta and inferior Qa cay a. As it covers the latter vessel it is placed behind the opening ° the lesser sac. It then continues its course to the right, and, V1 ng given a partial covering to the front of the right kidney, it sses over the right lateral and anterior walls of the abdomen as far the middle line. The left layer of the lieno-renal ligament, after V1 ng the left kidney, passes over the left lateral and anterior walls



of the abdomen, and, on arriving at the middle line, it becomes c tinuous with the right layer, which has just been traced as far as middle line. Along the posterior surface of the anterior wall of abdomen, in the middle line, above the level of the umbilicus, the p toneum meets with the ligamentum teres of the liver, around wb it is reflected, and here it is carried off from the abdominal wall to fc part of the falciform ligament.

Below the Transverse Colon, or at the Level of the Umbilicus .—Cc mencing at the middle line and passing to the right, the peritone covers the right half of the anterior abdominal wall and the ri, lateral wall as far as the lumbar region. It next covers the right si anterior surface, and left side of the ascending colon, whence it pas over the front of the right kidney at its lower and inner part. I


Fig. 457. — Diagram of the Peritoneum at the Level of the Opening 11

Lesser Sac (Transverse Section).

then reflected over the inferior vena cava, and, meeting with 1 superior mesenteric vessels, is carried off by them to the jejunum a ileum, both of which it invests. It is conducted back again to 1 vertebral column by the superior mesenteric vessels, thus forming 1 mesentery proper. It next passes to the left over the aorta, ai having partially covered the front of the left kidney at its lower a inner part, it meets the descending colon in the left lumbar regi* which it covers on the right side, anterior surface, and left si< Finally, it is reflected over the left lateral and left half of the anter wall of the abdomen as far as the middle line.

The relations of the peritoneum to the duodenum, pancreas, a kidneys will be described when these viscera fall to be considered.

Omenta. —The greater omentum extends from the greater curvature of the stomach and first inch of the first part of the duodenum to the ansverse colon, descending in its course usually as low as the pelvic im, and lower on the left side than on the right, which accounts for e greater frequency of an omental hernia on the left side. It covers e coils of the jejunum and ileum. Near the greater curvature of the omach it contains between its two layers the right and left gastrodploic arteries, and the epiploic branches of these vessels, which are ng and slender, descend into it. The greater omentum is often of lall size, thus leaving many of the coils of the small intestine uncovered, it may even be displaced into the left hypochondrium. It is com>sed of four layers of peritoneum, two of which, inseparably united, ascend from the greater curvature of the stomach to the region of e pelvic brim, these being called the anterior or descending layers. le other two layers, also inseparably united, ascend from the region


Fig. 458. — Diagram of the Peritoneum at the Level of the Umbilicus (Transverse Section).


the pelvic brim to the transverse colon, these being called the isterior or ascending layers. Between the two anterior and the two isterior layers there is usually, in healthy persons, a space which presents a part of the small cavity of the peritoneum, and is known > the lesser sac of peritoneum. In many cases, however, this space scarcely demonstrable on account of adhesions. It is most con)icuous a little below the greater curvature of the stomach.

The lesser omentum extends from the lesser curvature of the stomach fid first inch of the first part of the duodenum to the porta hepatis f the liver, and also to the fissure for ligamentum venosum. It is imposed of two layers of peritoneum which, at the lesser curvature f the stomach, contain between them the anterior and posterior ranches of the left gastric and pyloric arteries. For the most part s two layers are inseparably united, but at its right border, which is

ee , there lie between them the following structures: (1) the bile-duct 50


to the right side; (2) the hepatic artery, invested by the hepatic ple> of sympathetic nerves, to the left side; (3) the portal vein, which 1 between these two, and on a plane posterior to both; (4) a small super: pancreatico-duodenal tributary of the portal vein, which lies close the free margin of the omentum, and is usually the most anterior the structures enclosed; (5) lymphatic vessels; and (6) nerves. T] right or free border, with the foregoing contents, lies in front of t opening into lesser sac. The left border of the lesser omentum is sh< on account of the oblique position of the stomach, and is attached the diaphragm between the caval and oesophageal openings. T anterior layer of the lesser omentum is formed by peritoneum belongi to the greater sac, and the posterior layer by that belonging to t lesser sac, these two layers becoming continuous with each otl round the right or free border of the omental fold in front of the openi into lesser sac.

Mesenteries. —The mesentery proper is the fold of peritoneum whi attaches the jejunum and ileum to the vertebral column. Its vertebi border is called the root , and is comparatively short, measuring frc 5 to 6 inches in length. Its line of attachment extends from the co] mencement of the jejunum on the left side of the body of the seco: lumbar vertebra, at the anterior border of the pancreas, to the termir tion of the ileum in the right iliac fossa near the right sacro-iliac artic lation. This line of attachment passes obliquely from left to rigl and in this course the root of the mesentery proper crosses in success! the third part of the duodenum, aorta, inferior vena cava, and rig psoas major. The other border of the mesentery proper is called t intestinal border , and is attached to the jejunum and ileum througho their whole length. This border is of considerable length, and equ; that of the jejunum and ileum. The widening of the mesentery prop takes place gradually, so that it is thrown into a number of folc an arrangement which accounts for the coils of the jejunum and ileu] Its average breadth, from the root of the intestinal border, is abo 8 inches. The fold is composed of two layers of peritoneum, right superior, and left or inferior. The right or superior layer is continuo with the inferior layer of the transverse meso-colon, and with the pe toneum which covers the ascending colon, whilst the left or interi layer is continuous with the peritoneum which covers the descend! colon. Both layers are formed by peritoneum belonging to the great sac. The two layers contain between them the following structure

(1) the superior mesenteric vessels, and the jejunal and ileal arterie

(2) the superior mesenteric plexus of sympathetic nerves, and i secondary offshoots; (3) the lacteal vessels; (4) the mesenteric lymphal glands, and a variable amount of fat.

In some cases the mesentery proper presents one or more opening known as mesenteric holes, which may be congenital or traumat: If a portion of intestine slipped through one of these holes a mesentei hernia would result, and if the hole is situated in one layer only, therniated portion of intestine would take up a position in the space between the two layers. These openings are liable to be met with in at portion of the mesentery proper which is attached to the lower irt of the ileum, within the arch formed by the ileo-colic branch of e superior mesenteric artery and the last ileal artery.

In the mesentery of the jejunum, as distinct from that of the ileum, e fat is not uniformly distributed; near the intestinal border of this .rt of the mesentery areas are usually to be observed relatively free )m fat, and consequently translucent, the so-called ‘ windows ’ of e mesentery.

The mesentery of vermiform appendix or meso-appendix is a fold peritoneum which is derived from the left or inferior layer of the esentery proper near the terminal part of the ileum. It is triangular, d usually lies obliquely. Its right end reaches in a pointed manner the ileo-colic junction, and its left end forms a concave free border lich transmits the appendicular vessels and sympathetic plexus of rves. It seldom extends for more than half or two-thirds along the •pendix, which is thus rendered more or less convoluted or serpentine, may, however, extend along its entire length. In some cases it lies rtically, and then it loses its hold upon the mesentery proper, its tachment being transferred to the caecum, or right fascia iliaca, or en to the back of the ascending colon. The base of the appendix is metimes destitute of a mesentery, in which cases that portion of it closely connected to the posterior aspect of the caecum. Occasionally e entire meso-appendix is wanting, and then the appendix is found tiering to the back of the caecum. The meso-appendix may present small opening, through which a portion of bowel may pass and become

angulated. In .very rare cases the meso-appendix is disposed in ch a manner as to divide the ileo-colic fossa into an upper and a lower mpartment.

The transverse meso-colon is a broad fold of peritoneum which tends between the transverse colon and the posterior abdominal ill at the anterior border of the pancreas. Its layers contain between em the middle colic vessels, sympathetic nerves, and the lymphatics the transverse colon. Mesenteric holes may be present in the transrse meso-colon, under which circumstances a meso-colic hernia may cur.

The pelvic meso-colon is a fold of peritoneum which attaches the lvic colon to the lateral and posterior walls of the pelvis. It extends )m the inner border of the left psoas major (covered by the left 5 cia iliaca) near the left sacro-iliac articulation upwards and inwards the front of the promontory, and then downwards in the middle e to the front of the third sacral vertebra; its length is such as to ider the pelvic colon freely movable. It is composed of two layers disced laterally, and containing between them the superior rectal vessels, mpathetic nerves, lymphatic vessels, and a certain amount of fat.

The ascending and descending colons are each, in normal circummces, devoid of a mesentery. Occasionally, however, an ascending eso-colon and a descending meso-colon are present.


Peritoneal Ligaments — Ligaments of the Liver. — The perito ligaments of the liver are four in number (the ligamentum teres being regarded as of a peritoneal nature), and are as follows: falciform ligament, the coronary ligament, the right triangular ligam and the left triangular ligament.

The falciform ligament is also known as the suspensory ligam

It extends between the inferior surface of the diaphragm and posterior surface of the anterior abdominal wall on the one hand, the superior and anterior surfaces of the liver on the other. Its b which is free, extends from the umbilicus to the interlobar note] the liver, and contains between its two layers the ligamentum te The line of attachment of the ligament to the anterior and supe surfaces of the liver map the organ out into a right and left lobe, along this line the two layers of the ligament separate from each ot the right layer extending over the right lobe and the left over the lobe. Near the postero-superior border of the liver the two la] of the ligament diverge somewhat abruptly, and leave between tl a small triangular area which is destitute of peritoneum; they bec< continuous on either side with the superior layer of the coronary 1 ment.

The coronary ligament is also known as the posterior ligam

It is composed of two layers of peritoneum, superior and infei which are attached to the postero-superior and postero-inferior bor< of the liver on the one hand, and the diaphragm on the other. Tl layers are separated from each other by an interval, which correspo with the bare area of the right lobe of the liver. The superior It is continuous with the falciform ligament, and the inferior laye continuous with the peritoneum which covers the inferior vena c and the front of the right kidney.

The right and left triangular ligaments are situated at the extn right and left ends of the coronary ligament, and are formed by meeting at these points of the two layers of that ligament.

The ligamentum teres (round ligament) of the liver, though no peritoneal ligament, may here be described. It is a fibrous cord forr by the obliterated umbilical vein, and is contained within the bas< the falciform ligament between the umbilicus and the interlobar no of the liver, its course between these points being upwards, backwai and to the right. At the interlobar notch it enters the fissure ligamentum teres on the inferior surface of the liver, and terminates joining the left branch of the portal vein.

Although usually described as formed from a part of the (left) umbil vein, the ligamentum teres, where it lies in relation with the lower aspect of liver, is really the remnant of a secondary channel formed by communicai between the umbilical vein and the left vitelline vein. The -two umbilical v< run up in the body-wall and bulge into the small abdominal cavity, and in young embryo of the third week the left vein comes into association, through caudal part of septum transversum, with the left vitelline vein, establishin connection through which the umbilical blood of this side can pass directly to, liver and ductus venosus. When the right umbilical vein atrophies later, all



iod returned from the placenta is thus carried to the inferior vena cava by the nmunication. That part of the ligamentum teres lying in the abdominal 11 (canal of Richet) is a remnant of the umbilical vein, but that portion extding between this and the left division of the portal vein is the elongated ondary umbilico-vitelline communication.

On the surface of, or within, the ligamentum teres of the liver there are a few •y small veins, called para-umbilical veins. These anastomose at the umbilicus

h the epigastric veins of the anterior abdominal wall, and superiorly are conned with the left division of the portal vein. The anastomosis between these ns and the epigastric veins explains the enlargement of the veins of the anterior iominal wall in cases of portal obstruction within the liver.

The gastro-splenic ligament extends between the posterior surface the cardiac end of the stomach and the gastric surface of the spleen st in front of the hilum. It is formed of two layers, anterior and sterior, and is continuous with the greater omentum. The anterior ter is formed by peritoneum belonging to the greater sac, and the sterior layer by that belonging to the lesser sac. The fold contains tween its two layers the short gastric branches of the splenic artery. The other ligament of the stomach is called the gastro-phrenic ament. It is of small size, and extends between the region of the covered trigone of the stomach and the inferior surface of the iphragm, lying immediately to the left of the lower end of the oesoagus.

The ligaments of the spleen are two in number—namely, phrenicolenic or lieno-phrenic, and lieno-renal.

The phrenico-splenic or lieno-phrenic ligament is also called the spensory ligament. It extends between the spleen, near its upper tremity, and the contiguous part of the diaphragm. The lienotial ligament extends from the hilum of the spleen to the front of e left kidney at its upper and outer part. Its direction is backwards, d it is composed of two layers of peritoneum, right and left, which ntain between them the splenic branches of the splenic artery. The (ht layer corresponds with the posterior layer of the gastro-splenic

ament, and the left with the anterior layer of that ligament. The phrenico-colic ligament (sustentaculum lienis) extends between e splenic flexure of the colon and the diaphragm opposite the tenth eleventh left rib. It is triangular, and its surfaces are superior [ d inferior, its anterior border being free. It forms a platform upon hch the colic surface of the spleen rests.

The sustentaculum hepatis is a fold of peritoneum which is sometimes met th in connection with the ascending colon. (Treves found it in eighteen out one hundred bodies.) When present, it extends from the right side of the -ending colon to the abdominal wall at a point a little above the level of the ic crest. Its free border looks forwards, and it forms a shelf which supports e right margin of the liver.

Cavity of the Peritoneum. —The peritoneal cavity is divided into /0 compartments, greater and lesser, which communicate with each her through the opening into lesser sac behind the right or free border the lesser omentum.

The greater sac of peritoneum is the space which is exposed to view


after opening the abdominal cavity. It is separated from the le sac by the liver, lesser omentum, stomach, greater omentum, gas splenic ligament, lieno-renal ligament, and transverse meso-cc Its deepest parts with the subject lying in the supine position are, i exclude the pelvic recess, immediately lateral to the superior p of the kidneys, and it is to these parts that free fluid in the gen peritoneal cavity tends to gravitate.

The lesser sac of peritoneum (omental bursa) is an offshoot f the greater sac, the introversion taking place at the opening into le sac. It extends upwards behind the stomach to the posterior pai the inferior surface of the diaphragm and the caudate lobe of the li and downwards into the greater omentum.

Boundaries of the Lesser Sac — Anterior. —From below upwa the two anterior or descending layers of the greater omentum, posterior surface of the stomach, the lesser omentum, and the poste surface of the caudate lobe of the liver. Posterior .—From be upwards, the two posterior or ascending layers of the greater oment the transverse colon, the transverse meso-colon, and the ascent layer of the transverse meso-colon. Superior .—The posterior par the inferior surface of the diaphragm. Inferior .—The bend of greater omentum, where the two anterior or descending layers folded backwards, to become the two posterior or ascending lay Left .—The spleen; the gastro-splenic ligament; the lieno-renal ligann and the left border of the greater omentum.

In a great many cases that part of the lesser sac which is contai within the greater omentum is very limited in its downward exti on account of adhesions having formed between the layers of the gre; omentum.

Opening into Lesser Sac (Foramen of Winslow). —This is the oper by which the greater and lesser sacs of the peritoneum communic with each other. It is situated behind the right or free border of lesser omentum, on a level with the body of the twelfth thor; vertebra. Its direction is forwards and to the right, and it adr of the passage of one finger, and in some cases of two fingers. It however, often blocked by inflammatory products.

Boundaries — Anterior. —The right or free border of the les omentum, containing between its two layers (i) the bile-duct to right side; (2) the hepatic artery, invested by the hepatic plexm sympathetic nerves, to the left side; (3) the portal vein, which between these two, on a plane posterior to both; and (4) lymph; vessels. Posterior .—The inferior vena cava covered by peritonei Superior .—The caudate process of the liver. Inferior .—The first p of the duodenum, and the hepatic artery in the first part of its cou as it curves forwards and upwards from the coeliac axis. If the open is blocked by inflammatory products, and fluid is effused into lesser sac, the condition known as hydrops saccatus results. It is poss: for a loop of bowel to pass through the foramen, thus forming variety of internal hernia.


Peritoneal Recesses or Fossae. —The peritoneum presents in certain situations tall pockets, which are known as peritoneal recesses. Their importance conts in the fact that a small portion of intestine may enter one or other of them d become strangulated, thus constituting an internal hernia, which, except in e cases of the inguinal recesses, is called a retro-peritoneal hernia. The recesses, cording to their situation, are called duodenal, duodeno-jejunal, peri-csecal, d intersigmoid.

Duodenal Recesses. —Four varieties of duodenal recesses are met with in conction with the terminal part of the duodenum—namely, inferior duodenal, perior duodenal, para-duodenal, and retro-duodenal (Jonnesco).

The inferior duodenal recess is the most common and largest. It is situated the left side of the terminal part of the duodenum, and opens upwards. It is unded in front by a thin triangular portion of peritoneum, called the inferior


Fig. 459.— Duodenal Recesses: Duodenum turned toward the Right.

Arrows: 1 and 2, inferior and superior duodenal recesses, overhung by corresponding folds; 3, para-duodenal recess.


lodenal fold, which presents a free crescentic border or base superiorly. The ssa may admit the thumb, and may be nearly an inch deep. It is said to be esent in 75 per cent, of cases (Jonnesco).

The superior duodenal recess is less constant, and of smaller size, than the ferior, and lies about an inch above it. It opens downwards, and its orifice ces that of the inferior duodenal recess. It may admit the tip of a finger, is bounded in front by a thin triangular portion of peritoneum, called the perior duodenal fold, which presents a free crescentic border or base interiorly. ie recess is said to be present in 50 per cent, of cases (Jonnesco).

The para-duodenal recess is situated a little to the left of the terminal part the duodenum. It is bounded on the left side by a fold of peritoneum, proiced by the inferior mesenteric vein.

The retro-duodenal fossa is situated behind the terminal part of the duo:num.




Duodeno-jejunal Recess. —This recess, when present, contains the duodei jejunal flexure, and leads upwards and towards the left side. It is bounc by two free portions of peritoneum, called the duodeno-meso-colic folds, and has the pancreas above, the left kidney on the left, and the aorta on the rig It is said to be present in from 15 to 20 per cent, of cases.

Peri-caecal Recesses. —These recesses are three in number—namely, super ileo-caecal, inferior ileo-caecal, and retro-caecal.

The superior ileo-caecal recess is situated in the angle between the terminati of the ileum and the commencement of the ascending colon in front of the adj ace part of the mesentery proper. It opens inwards, and is bounded in front b} portion of the peritoneum, called the vascular fold of caecum, which is produc by the anterior caecal artery; behind, by the mesentery proper; below, by 1 ileum; and, on the right side, by the commencement of the ascending colon, size and depth the recess is small. The vascular fold of caecum in some ca; reaches downwards as in Fig. 461 to the caecum, and may then be more prope: called an ileo-caecal fold.

The inferior ileo-caecal recess is situated in the angle of junction of the ilei and caecum, and opens downwards and inwards. It may extend upwards foi


Asc. Colon Ileum Pelvic Colon


biG. 460.— Intersigmoid Fossa in a Child (after Poirier).


variable distance behind the ascending colon, and sometimes is capable admitting two fingers. It is bounded anteriorly and inferiorly by a portion peritoneum, called the ileo-caecal fold (bloodless fold of Treves); posteriorly, 1 the meso-appendix; laterally, by the caecum; and superiorly by the posteri aspect of the terminal part of the ileum and the inferior layer of the mesentei proper. The importance of this recess consists in the fact that it often contaii the vermiform appendix, or a portion of it. The ileo-caecal fold in certain cas is attached more to the appendix than to the caecum, and is often then called t] ileo-appendicular fold. It may contain a small recurrent branch of the a pendicular artery.

I he retro-csecal recess is situated behind the caecum, on the outer side of tl meso-appendix. It may extend upwards for a variable distance behind tl ascending colon, and is sometimes divided vertically into two or more compar meats. It occasionally contains the vermiform appendix, or a portion of it.

Intersigmoid Recess. —This recess is of rare occurrence in the adult, but frequently present in early infancy. It is situated behind the pelvic meso-colc near the bifurcation of the left common iliac artery, at the point where tl


ached border of the meso-colon changes its direction. It opens downwards i towards the left side. In its anterior wall one of the lower left colic branches the inferior mesenteric artery is frequently to be found; in its posterior wall

the ureter. In early life the alimentary tube is short and medium. It does not possess rue ventral mesentery at any stage in the human embryo. The ventral and •sal mesocardia, though lying ventral to the fore-gut, are derived from the icardial walls, and are not properly concerned with the alimentary tube, ile the only definite ' ventral ’ mesentery associated with this tube, the ventral itro-duodenal fold, is really a secondary drawing out and thinning of the turn transversum. This septum ( q.v.), however, might in itself be looked on in some ways representing a broad ventral mesentery, connecting the fore-gut

h the ventral body-wall (see pp. 46 and 80). The ventral gastro-duodenal mesentery extends from tfie ventral aspect of s primitive stomach and upper part of the duodenum to the ventral body11 on the cephalic side of the umbilicus. It is the lower layer of the septum



Fig. 461.— Ileo-clecal Fold and Recesses (after Jonnesco).


nsversum, within which the liver undergoes development. As the liver spends, it carries with it the ventral gastro-duodenal mesentery, which it ndes into two parts. The part between the liver and (1) the ventral portion the diaphragm, and (2) the ventral wall of the abdomen as low as the umbilicus, ms the falciform ligament of the liver; and the part between the liver (porta patis) and stomach (lesser curvature) forms the lesser or gastro-hepatic

tentum.

P r * m itive dorsal mesentery receives names corresponding to the parts the alimentary tube with which it is connected. Thus, in the abdomen there 5 the meso-gastrium, meso-duodenum, meso-jejunum, meso-ileum, meso pendix, meso-colon (ascending, descending, iliac, and pelvic), and meso dum.


As development proceeds, these mesenteric folds undergo important changes, the dorsal meso-gastrium, though primitively median, is pouched out very ay to the left to form the lesser sac ; this projects as a thin-walled sac into the side of the abdominal cavity below the liver, carrying the stomach in its front wall. Its opening looks to the right; it is attached here, and continu< with the meso-duodenum and general mesentery. Otherwise it lies free betw< the mesentery and left lobe of liver. When the umbilical sac discharges ■ intestinal coils, they displace the lesser sac and stomach to the left and upwa and push the colon and median meso-colon to the left and backwards, so tl these lie behind the coils and are overhung by the lower part of the lesser s projecting below the stomach (see Figs. 511 and 512). This projection of 1 lesser sac, at first unattached to the colon, on which it lies, is the early grea omentum. The lesser sac fuses with the peritoneum of the back wall, as a does the meso-colon, so far as its originally median part is concerned; thus 1 lesser sac is fixed above, while below this is the primitive transverse meso-coli On referring to Fig. 463, it will be seen that in this region there are four layers peritoneum at this stage. The upper two layers are continuous with the two p


Fig. 462. —The Retro-c,ecal Recess (after Jonnesco).


terior or ascending layers of the greater omentum, and represent the origir meso-gastrium. The lower two layers belong to the primitive transverse met colon. Subsequently the lower of the upper two layers and the upper of t] lower two layers unite and disappear. There are thus left only two layers of pei toneum, which constitute the transverse meso-colon of the adult, the lower lay of which is part of the primitive transverse meso-colon, whilst the upper layer part of the greater omentum. In fact, both layers are ultimately derived frc the two posterior or ascending layers of the greater omentum. As the resi of these changes, the pancreas comes eventually to lie behind the peritoneu whereas it was originally contained between the two layers of the meso-gastriu The inferior mesenteric vessels reach the intra-abdominal colon by runni between the layers of the median mesentery (meso-colon); when this is fore against the left dorsal wall by the pressure of the coils of gut, and adheres the the vessels are left behind the peritoneum.



The ascending and descending meso-colon, as a rule, disappear as a result of Ihesion.

The pelvic meso-colon persists and the meso-rectum disappears.

Structure of the Peritoneum. —The peritoneum is a typical serous membrane

e the pleura, the serous portion of the pericardium, and the tunica vaginalis, •iefly stated, it consists of a homogeneous connective-tissue basement memane, containing elastic tissue, and lined with endothelium.


s. 463.— Scheme, based on Embryonic Conditions, to show Fcetal Arrangements of Peritoneum and Composition of Transverse Mesocolon.

The wall of the lesser sac is really composed of two layers, but these

layers are not shown in the figure.

Development. —'The parietal peritoneum is developed from the somatic meso'Ul of the somatopleure of the body-wall. The visceral peritoneum is developed

m the splanchnic mesoderm of the splanchnopleure of the primitive intestinal

)e.

Blood-supply of the Intestinal Canal. —The intestinal canal receives blood-supply from the superior and inferior mesenteric arteries, th the exception of the upper portion of the duodenum and a portion the rectum.


Superior Mesenteric Artery. —This vessel springs from the front c the abdominal aorta about \ inch below the coeliac artery. It is a first directed downwards behind the body of the pancreas and th splenic vein. It then passes downwards and forwards in front of th uncinate process of the pancreas and third part of the duodenum, a the lower border of which latter it takes up its position between th two layers of the mesentery proper. The vessel then passes down wards near the root of the mesentery, its course being slightly curve*


Fig. 464. — The Superior Mesenteric Artery and its Branches (after Spalteholz).

with the convexity towards the left side, and it terminates near the ileo-colic junction in the last ileal artery, which anastomoses with the ileal branch of the ileo-colic artery. The vessel is surrounded by a tough sheath formed by the superior mesenteric sympathetic plexus.

Branches — Left Branches .—These are called the jejunal and ileal arteries (rami intestini tenuis), and are at least twelve in number. They pass downwards and to the left between the two layers of the mesentery proper, and supply the jejunum and ileum. After a course of about 2 inches each divides into two branches, which by their junction with

)ntiguous branches give rise to primary arcades. From the conexities of these arcades small branches .are given off, which act in a milar manner, and give rise to secondary arcades. This disposition of rteries goes on so as to form tertiary, quaternary, and even quinary rcades. The minute vessels arising from the arcades of the last er enter the wall of the jejunum and ileum along the mesenteric order, where each divides into two branches, which encircle the owel beneath its serous covering, thus providing for an equal arterial apply to all parts of the wall. From the rings thus formed branches enetrate deeply to reach the mucous coat. Each jejunal and ileal rtery, as well as its various branches, conducts to the bowel an offshoot f the superior mesenteric sympathetic plexus.

The branches from the terminal arcades divide some distance away

om the intestine, and diverging leave an interval into which the itestine can expand without throwing undue strain on the vessels, 'his arrangement obtains generally all along the abdominal portion f the alimentary canal.

Right Branches — Ileo-colic Artery. —This vessel is the lowest of tie right branches, and in many cases it arises in common with the ight colic. Its course is downwards and outwards towards the right iac fossa behind the peritoneum, and it divides into two branches, scending and descending. The ascending branch (colic branch) passes pwards and forms an arcade with the descending branch of the right olic, from which branches proceed to the lower part of the ascending olon. The descending branch (ileo-ccecal branch) passes to the upper •art of the ileo-colic junction, where it furnishes the following branches: leal, to the terminal part of the ileum, where it anastomoses with the ist ileal artery; appendicular , which, descending behind the terminal >art of the ileum, passes between the two layers of the meso-appendix, nd so reaches the vermiform appendix; anterior ccEcal , to the front of he caecum; and posterior ccecal, to its posterior aspect.

Right Colic Artery. —This is the second branch in order from below ipwards, and in many cases it arises in common with the ileo-colic. ts course is transversely to the right behind the peritoneum, and it livides into two branches, descending and ascending. The descendng branch anastomoses with the ascending branch of the ileo-colic, and he ascending branch with the right branch of the middle colic. The ircades thus formed furnish branches to the ascending colon, which n their course form secondary and tertiary arcades.

Middle Colic Artery. —This vessel arises from the right side and ront of the main trunk about 2 inches above the right colic on a level vith the lower border of the third part of the duodenum. Its course s forwards between the two layers of the transverse meso-colon, and it livides into a short right and a long left branch. The right branch mastomoses with the ascending branch of the right colic, and the eft branch with the ascending branch of the upper left colic from the nferior mesenteric. The arcades thus formed furnish branches to the niddle colon, which in their course form secondary and tertiary arcades.


Inferior Pancreatico-duodenal Artery.— This small vessel usual; arises from the right side of the main trunk opposite the upper bord< of the third part of the duodenum, but it may spring from the fir; jejunal artery. Its course is to the right behind the superior mesenter vein, and between the head of the pancreas and the third part of tl duodenum. It terminates by dividing into two branches, anteri< and posterior, which ascend one in front of the other behind the hea of the pancreas supplying it and the adjacent portions of the duodenur and anastomosing with the anterior and posterior branches respective; of the superior pancreatico-duodenal of the gastro-duodenal from tl


Fig. 465. —Schematic Drawing to show Upper Branches of Superic

Mesenteric Artery.

Non-peritoneal area stippled; A, TT, ascending and transverse meso-colon M, middle colic; R, right colic; IC, ileo-colic; I VC, inferior vena cava.

hepatic. The vessel is accompanied by an offshoot from the superi( mesenteric sympathetic plexus, and when it arises from the first jejun; artery it passes behind the superior mesenteric artery.

Superior Mesenteric Vein.— This vein is formed by tributaries whic return the blood from the parts of the intestinal canal supplied by tl superior mesenteric artery, and it receives in addition the right gastr* epiploic vein. It ascends on the right -side of the superior mesenter artery. After leaving the mesentery it passes over the third part «  the duodenum and uncinate process of the pancreas, and finally, behir the neck of the latter organ, joins the splenic vein to form the port


n. The vessel and its tributaries are destitute of valves, so that the od can regurgitate in cases of portal obstruction.

Superior Mesenteric Sympathetic Plexus. —This plexus is derived n the solar plexus. It closely surrounds the superior mesenteric sry in the form of a tough sheath, and furnishes offshoots which ompany all the branches of that vessel.

Lymphatic Vessels of Small Intestine. —These, which are called

eals, originate in the villi of the mucous membrane of the small sstine (see p. 866). They leave the wall of the bowel at the mesenlc border, those of the jejunum exceeding in number those of the im. Within the mesentery they take a course inwards and up:ds, becoming in succession the afferent and efferent vessels of the ups of mesenteric glands. At the root of the superior mesenteric 5 ry the lacteals, which have now emerged from the innermost


Fig. 466. —Portion of Jejunum with its Mesentery, showing Lacteal Vessels and Mesenteric Glands.

senteric glands, terminate in from one to four lymphatic trunks, ich open into the cisterna chyli.

Superior Mesenteric Glands. —These are about 150 in number, and situated within the mesentery proper and along the course of the nk of the superior mesenteric artery. In health their average size ibout that of a small pea, except along the course of the main artery, ere they are somewhat larger; they are more numerous in the jejunal m in the ileal mesentery. They receive the lacteals from the lower "t of the duodenum, the jejunum, and the ileum, and also the lymatics from the ascending and transverse colon. The glands may divided into three groups: a group of large and important glands the root of the mesentery, particularly numerous along the upper d of the superior mesenteric vessels; a second group in the neighboured of the first arterial arcades; and a third group of small glands in 5 neighbourhood of the terminal arcades; certain of this last group L V lie, especially in the upper jejunal region, in close proximity to i intestine or even upon it.


In the ileo-colic angle there is a special group of glands, called ileo-colic glands. These receive afferent vessels from' the termi part of the ileum, the caecum, the vermiform appendix, and beginn of the ascending colon; their efferent vessels pass to the innerm group of superior mesenteric glands. The efferent vessels of superior mesenteric glands usually unite with those of the coe glands to form one or more intestinal trunks, which, joining the effer


Fig. 467. —The Inferior Mesenteric Artery and its Branches (after Spalteholz).


lymphatics from the pre-aortic and retro-aortic glands, form 1 cisterna chyli.

Lymphatic Vessels of Ascending and Transverse Colon. —The ly

phatics of the ascending colon terminate in two ways as follow those from the lower part pass to the innermost group of super mesenteric glands, whilst those from the upper part go to the me: colic glands. The lymphatics of the transverse colon become affen vessels of the meso-colic glands, the efferent vessels of which j<


e terminal intestinal lymphatic trunks from the superior mesenteric mds. The lymphatic vessels from the transverse colon freely comLinicate with those in the greater omentum.

Inferior Mesenteric Artery. —This vessel arises from the front of e abdominal aorta towards its left side about ij inches above the Eurcation. Its course is downwards and to the left towards the t iliac fossa. It is behind the peritoneum, and lies first upon the rta, and then on its left side, where it is supported by the psoas ijor. Subsequently it is continued as the superior rectal artery er the left common iliac vessels. The artery is surrounded by the Eerior mesenteric sympathetic plexus.

Branches—Upper Left Colic Artery. —This vessel passes transversely the left, behind the peritoneum and over the lower part of the left Iney, and divides into two anches, ascending and deeding. The ascending inch anastomoses with the t branch of the middle lie, and the descending mch with the ascending anch of the lower left colic tery. The arcades thus rmed supply branches to e left extremity of the msverse colon and the

scending colon, which in eir course form secondary Ld tertiary arcades.

Lower Left Colic Arteries igmoid Arteries) . — These e usually three in number -superior, middle, and inrior—but they are very triable and may arise as single trunk. They pass )wnwards and to the left 7 er the psoas major, ureter, and testicular vessels, and supply te lower part of the descending colon and the pelvic colon. The [perior lower left colic artery , which lies, as a rule, behind the perineum, divides into two branches, ascending and descending. The sending branch forms an arcade with the descending branch of the pper left colic, and the descending branch passes between the two yers of the pelvic meso-colon, where it anastomoses with the middle wer left colic artery; this artery, or one of its branches, may lie in the iterior wall of the intersigmoid recess. The middle and inferior wer loft colic arteries pass between the two layers of the pelvic meso)lon, where they form arcades with the descending branch of the iperior lower left colic, with one another, and with the superior rectal


Fig. 467A. — Schematic Drawing to show the Lymphatic Arrangements for Ascending and Greater Part of Transverse Colon.

The glands are grouped along branches of the superior mesenteric artery.



artery. The branches of these arcades form secondary, or ev< tertiary, arcades before the terminal branches are given off.

The superior rectal artery (superior hsemorrhoidal artery) is tl

continuation of the inferior mesenteric, and will be found describ( on p. 961.

Inferior Mesenteric Vein.—This vein is formed by tributaries whi( return the blood from the parts of the large intestine supplied 1 the inferior mesenteric artery. It lies at first near the left side of i artery, but soon leaves it and ascends on the left psoas major, whe it lies on the left side of the aorta behind the peritoneum. In th course it crosses the left testicular artery and left renal vein. It pass<

to the left of the duodeno-jejun flexure lying in the anterior wall 1 the paraduodenal recess, and the curving sharply to the right, passi behind the pancreas to join the splen vein near its termination in the port vein. It may, however, open ini the angle of junction of the splen and superior mesenteric veins, or ini the superior mesenteric vein near i termination. The inferior mesenter vein and its tributaries are destitui of valves, so that the blood can n gurgitate in cases of portal obstru< tion.

Inferior Mesenteric Sympathet: Plexus.—This plexus is derived froi the left half of the aortic plexus. ] forms a tough sheath round tt artery, and furnishes offshoots wit its branches.

Inferior Mesenteric Glands.—Thes glands are situated around the roc and along the trunk and branches c the inferior mesenteric artery. Thos around the root of the vessel cor


Fig. 467B. — Scheme to illustrate the Lymphatic Drainage of Descending Colon and Iliac Loop, and Terminal Portion of Transverse Colon.


stitute the inferior mesenteric group of the pre-aortic glands.

The afferent vessels are derived from (1) the lower part of the descent ing colon , (2) the iliac part of descending colon, (3) the pelvic color and (4) some of the lymphatics of the rectum.

Their efferent vessels pass to the inferior mesenteric group of pre aortic glands.

Lymphatic Vessels of Descending and Pelvic Colon.—The lymphatic of the descending colon are singularly scanty; they terminate in two way as follows: those of the upper part pass to the meso-colic glands, whils those of the lower part with the lymphatics of the pelvic colon pas to the inferior mesenteric group of pre-aortic glands.



THE ABDOMEN


803

Lymphatic Glands of Large Intestine (Colic Glands).—The glands i arranged in groups, named according to the portion of intestine which they are related, and they are situated behind the respective rts, except those belonging to the transverse colon, which lie between 3 two layers of the transverse meso-colon, and are known as the iso-colic glands.

Position and Connections of the Duodenum.—The duodenum is 3 first part of the small intestine. It measures from 10 to 11 inches length and is the widest and least movable part. It extends from


Kidneys (RK, LK).

SP, testicular vessels; U, ureter; A, aorta; I VC, inferior vena cava.


s pylorus to the left side of the body of the second lumbar vertebra, lere it ends in the jejunum. It describes a somewhat U-shaped rve with the concavity directed upwards and to the left in close aptation to the head of the pancreas. It is devoid of a mesentery, d is divided into three parts—first, second, and third.

First or Superior Part.—The first part extends from the pylorus the right side of the neck of the gall-bladder. It lies in the epistnc region, and is about 2 inches in length, its direction being wards, backwards, and to the right when the stomach is empty, but ectly backwards when that organ is distended. The lesser omentum


furnishes a complete covering to about the first inch; the remainder i covered by peritoneum only in front. The first part is therefore com paratively movable.

Relations— Superior. —The caudate process of the liver and th hepatic artery. Anterior.— The quadrate lobe of the liver and the gal] bladder. Posterior. —The portal vein, gastro-duodenal artery, bile duct, and neck of the pancreas. Inferior. —The head of the pancrea and the division of the gastro-duodenal artery into its terminal branches The first part lies below the opening into lesser sac.

Second or Descending Part.—This part extends from the right sid of the neck of the gall-bladder to the right side of the body of the thin (sometimes fourth) lumbar vertebra. It lies at first in the epigastric and subsequently in the umbilical region; its length is from 3 to 4 inches and its direction is almost vertically downwards behind the right ex tremity of the transverse colon. The anterior surface is covered b; peritoneum, except opposite the transverse colon. If there is n< transverse meso-colon at this point, there is a distinct area left un covered and connected to the colon by areolar tissue. If, however there is a transverse meso-colon present at this point, the bare area i trifling. The posterior surface is destitute of peritoneum. The secom part is therefore very immovable.

Relations— Anterior. —From above downwards the liver and th gall-bladder near its neck, the right extremity of the transverse colon and some coils of the small intestine. Posterior. —The anterior surfac of the right kidney near the hilum, the inferior vena cava, and th psoas muscle. Right. —The right flexure of the colon, and the righ lobe of the liver. Left. —The head of the pancreas, which may encroacl upon it both anteriorly and posteriorly, the bile-duct, and the anterio and posterior branches of the superior and inferior pancreatico-duodena arteries. The bile-duct and pancreatic duct enter the wall of this par at the junction of the inner and posterior aspects a little below th centre.

Third or Inferior Part.—This part extends from the right side 0 the body of the third (sometimes fourth) lumbar vertebra to the lef side of the body of the second on a level with its upper border. A this point it makes a sharp bend forwards, and terminates in th jejunum, thus forming the duodeno-jejunal flexure. It lies at first h the umbilical, and subsequently in the epigastric region; its lengt is about 5 inches, and its direction is at first obliquely to the left an< upwards, and afterwards vertically upwards. Its anterior surface i covered by peritoneum derived from the descending layer of the trans verse meso-colon, except where it has the superior mesenteric vessel in front of it. There is no peritoneum behind it, and consequently i is fixed in position.

Relations— Anterior. —The superior mesenteric vessels and the uppe' part of the root of the mesentery, with portions of the small intestinf on either side of these. Posterior .—The inferior vena cava, aortj (below the origin of the superior mesenteric artery), left renal vein


ft psoas major, and left crus of the diaphragm. Superior .—The >wer part of the head of the pancreas (including its uncinate process), nd the inferior pancreatico-duodenal vessels.

The terminal portion of the third part is sometimes spoken of as he fourth or ascending part of Treves. It is covered by peritoneum n the left side, as well as in front, and in cases where a retro-duodenal scess is present it is partially covered by peritoneum behind towards re left side. The duodenal recesses of the peritoneum are met with n the left side of this portion. The duodeno-jejunal flexure is suspended from the right crus of the diaphragm by a fibro-muscular undle, called the suspensory muscle of duodenum. The muscle consists f both striped and unstriped muscular fibres, as well as of elastic ^ssue; as it passes downwards it lies in a fold of peritoneum called the uodeno-jejunal fold immediately to the right of the coeliac artery. Its bres are inserted mainly into the posterior surface of the duodeno"junal flexure, but certain of them are continued into the mesentery.


Fig. 469.—The Arteries of the Stomach, Duodenum, Pancreas, and Spleen.



Blood and Nerve Supply of the Duodenum.—The arteries of the uodenum are as follows: (1) the right gastric branch of the hepatic; 2) the superior pancreatico-duodenal branch of the gastro-duodenal


of the hepatic; and (3} the inferior pancreatico-duodenal branch of t superior mesenteric, ?&»&*&**£** »

The veins terminate in the superior mesenteric, splenic, and pori veins.

The nerves are derived from the hepatic and superior mesentei sympathetic plexuses.

The lymphatic vessels of the first part of the duodenum pass to t retro-pyloric glands, and those of the second and third parts pass the prepancreatico-duodenal and retro-pancreatico-duodenal glanc which lie along the anastomotic chains formed by the anterior ai posterior branches of the pancreatico-duodenal arteries.

Position and Connections of the Pancreas.—The pancreas is a loi narrow gland which is situated behind the stomach on a level with i first and second lumbar vertebrae. Its right extremity occupies i. duodenal curve, and its somewhat pointed left extremity is in conta with the spleen. The greater part of the organ lies in the epigasti region, but its left extremity is situated in the left hypochondriur The .anterior surface is covered by the ascending layer of the transver me9L-colon, and the inferior surface by the descending layer, but tl posterior surface is destitute of serous covering. The length of tl organ is from 6 to 8 inches, its depth from 1 to ij inches, except at tl right and left extremities, and its thickness from 1 to £ inch. I weight is about 3J ounces. It has been likened in shape to the capit letter J laid thus c- (Birmingham). For convenience of descriptic it is divided into a head, neck, body, and tail.

The head is the enlarged flattened right extremity. It chief corresponds with, and is closely attached to, the second and thii parts of the duodenum as far almost as the duodeno-jejunal flexur The expansion of the head to the left along the upper part of the thii portion of the duodenum is called the uncinate process.

Relations— Anterior. —The transverse colon with its meso-coloi and the superior mesenteric vessels crossing the uncinate proces The formation of the portal vein may occur in front of the upturne extremity of the uncinate process. Posterior— The inferior-vena cav right renal vessels, right crus of the diaphragm, aorta, and left ren; vein. Superior. —The first part of the duodenum and the superic pancreatico-duodenal artery. Inferior. —The third part of the du< denum, and the inferior pancreatico-duodenal artery. Right. —Tl second part of the duodenum, with the bile-duct behind, as low e a little below the centre, and the anastomoses between the superi( and inferior pancreatico-duodenal arteries. '

The neck may be defined as the part in front of the origin of the ver portae and the termination of the superior mesenteric vein. It. spring from the anterior surface of the head near its upper part; and. i*s aboij 1 inch in length. Its direction is upwards and to the left, and forms the connecting link between the head and body. The gastr* duodenal and superior pancreatico-duodenal arteries occupy groov| on its right side; the commencement of the first part of the duodenum in front of it, whilst the origin of the portal vein and the termination f the superior mesenteric vein are behind it.

The body passes to the left with a slight inclination backwards fter it has crossed the aorta. It is triangular, and presents three arfaces (anterior, posterior, and inferior) and three borders (superior, nterior, and posterior).

The anterior surface, which is covered by peritoneum, is in relation ith the posterior surface of the stomach. At its right extremity, 1st below the coeliac artery, it presents a prominence, called the fiber omentale from its relation to the lesser omentum. The tuber mentale of the pancreas, it will be noticed, lies behind the lesser mentum, whereas that of the liver lies in front of it. The posterior urface, which is destitute of peritoneum, is related to the following tructures: the aorta below the coeliac artery, with a portion of the oeliac plexus; the origin of the superior mesenteric artery; the left iprarenal gland; and the left kidney with its vessels. The.splenic ein passes from left to right in contact with this surface near the iperior border. The inferior surface, which is covered by peritoneum,

moulded on the duodeno-jejunal flexure, some coils of the jejunum, nd the left extremity of the transverse colon. The coeliac artery promts forwards over the superior border above the tuber omentale. To he left of this artery the splenic artery pursues its tortuous course to he spleen, and to the right of it the hepatic artery lies for a short istance. The transverse meso-colon is attached to the anterior border, long which its separation into ascending and descending layers takes lace, the former covering the anterior surface of the organ, and the itter, on its way backwards, investing the inferior surface. The osterior border presents nothing noteworthy.

T 1 j tail corresponds with the left extremity where the pancreas is arrowest, and is in contact with the lower end of the gastric surface f the spleen behind the hilum. The terminal part is in the lieno-renal igamentt

For the structure and development of the pancreas, see pp. 891, 894.

Coeliac (Solar) Plexus et the Sympathetic System. —The coeliac plexus 3 of large size, and is situated deeply in the epigastric region, behind he stomach and in front of the crura of the diaphragm and the aorta lose to the origins of the coeliac artery and superior mesenteric artery, t extends from one suprarenal gland to the other, and is composed f nerve-fibres and ganglia. The plexus receives its chief fibres from he greater and lesser splanchnic nerves of each side, which contain a irge number of spinal fibres. The greater splanchnic nerve is formed >y rqots derived usually from the fifth to the ninth or tenth thoracic ympathetic ganglia inclusive, and it enters the abdomen by piercing he crus of the diaphragm. The lesser splanchnic nerve arises by two oots from the ninth and tenth thoracic ganglia, and it also enters he abdomen by piercing the crus of the diaphragm. The plexus also eceives fibres from the right vagus nerve. Two of the ganglia of the 'celiac plexus are of large size, and are situated one at either lateral



Fig. 470. —The Sympathetic System in the Abdomen and Pelvis (Hirschfeld and Leveille).

R.K., right kidney; R.T., right testis,



le. They are called the cceliac ganglia (semilunar ganglia), right and t. Each lies over the corresponding crus of the diaphragm close the suprarenal gland, that of the right side being under cover of e inferior vena cava, and each receives at its upper part the greater lanchnic nerve. The lower part of each ganglion is more or less tached, and is known as the aortico-renal ganglion, which lies over e root of the renal artery, and in which the lesser splanchnic nerve rminates. From each cceliac ganglion branches proceed in a radiating inner upwards, outwards, downwards, and inwards. The inner oup of fibres extend from one ganglion to the other, embracing the diac artery as they cross the aorta, and forming the cceliac plexus, lich receives fibres from the right vagus nerve, and contains numerous lall ganglia.

The cceliac plexus furnishes three secondary plexuses—superior stric, splenic, and hepatic. The superior gastric plexus accompanies e left gastric artery to the lesser curvature of the stomach, and supies branches to the adjacent portions of the anterior and posterior rfaces of that organ. The splenic plexus goes with the splenic artery, id receives branches from the right vagus nerve. It is distributed, th the branches of the artery, to the pancreas, cardiac extremity of e stomach, left half of its greater curvature and adjacent portions its surfaces, and the spleen. The hepatic plexus accompanies the tery of that name, and receives branches from the left vagus nerve, s distribution corresponds with that of the artery, and its offshoots e as follows: pyloric to the lesser curvature of the stomach; gastrolodenal, dividing into right gastro-epiploic to the greater curvature the stomach, and superior pancreatico-duodenal to the head of the .ncreas, and the first and second parts of the duodenum; cystic to the 11 -bladder; and hepatic to the liver.

The diaphragmatic or phrenic plexus receives its fibres from the >per part of the coeliac ganglion, and it accompanies the phrenic artery the diaphragm, giving branches in its course to the suprarenal plexus. The suprarenal plexus receives its fibres from the coeliac ganglion d coeliac plexus. It contains small ganglia, and is joined from »ove by branches from the phrenic plexus, and below by branches )m the renal plexus. It is distributed to the suprarenal gland.

The renal plexus derives its fibres from the aortico-renal ganglion, e coeliac and aortic plexuses, and the lowest splanchnic nerve when esent. (The lowest splanchnic nerve arises from the eleventh oracic ganglion, and enters the abdomen behind the medial arcuate

ament, or through the crus of the diaphragm.) The fibres of the nal plexus, which contain ganglia here and there, are distributed th the renal artery to the kidney, branches being also given to the prarenal plexus, testicular plexus (ovarian in the female), and to the eter.

The superior mesenteric plexus is a continuation of the coeliac exus, and also receives fibres from the coeliac ganglia. It contains ganglion, called superior mesenteric, in contact with the origin of


Fig. 471. —Scheme of the Sympathetic Nerve in the Abdomen and Pelvis (Flower).


S.C. Sympathetic Trunk 1,2,3,4. Lumbar Ganglia a,b,c,d, Pelvic Ganglia G.I. Ganglion Impar

G. S. Greater Splanchnic S.S. Lesser Splanchnic L.S. Lowest Splanchnic D.P. Phrenic Plexus

S.R.P. Suprarenal Plexus

R. P. Renal Plexus

S. P. Testicular Plexus A.P. Aortic Plexus

I.M.P. Inferior Mesenteric Plexus L.C.P. Upper Left Colic Plexus S.P. Lower Left Colic Plexus S.H.P. Superior Rectal Plexus

H. P. Hypogastric Plexus

R.I.P. Jejunal and


P.P. Pelvic Plexus E.P. Epigastric Plexus C.P. Cceliac Plexus S.P. Splenic Plexus Pa.P. Pancreatic Plexus

L. G.P. Left Gastro-epiploic Plexus

B. S. Branches to Spleen

G. P. Superior Gastric Plexus

H. P. Hepatic Plexus Pvl.P. Pyloric Plexus

G.D.P. Gastro-duodenal Plexus

C. P. Cystic Plexus B.L. Branches to Liver

S.M.P. Superior Mesenteric Plexus I.C.P. Ileo-colic Plexus R.C.P. Right Colic Plexus

M. C.P. Middle Colic Plexus Plexuses



ie artery of that name, and it accompanies that vessel and its branches d be distributed to the intestinal canal from the middle of the duoenum to the commencement of the descending colon. Its secondary lexuses are as follows: jejunal and ileal, ileo-colic, right colic/middle Dlic, and inferior pancreatico-duodenal.

The abdominal aortic plexus derives its fibres from the coeliac ganglia nd the coeliac plexus. It extends along the aorta, beyond the origin f the superior mesenteric artery, in the form of two lateral strands hich communicate freely with one another over the vessel by many iterlacing fibres. It is reinforced laterally by branches from the imbar portion of the gangliated sympathetic trunk. The two lateral irands of the plexus ultimately cross the common iliac arteries, and nite in front of the body of the fifth lumbar vertebra to form the ypogastric plexus. The aortic plexus furnishes, on either side, ranches to the lenal and testicular (or ovarian) plexuses, and supplies le coats of the aorta. The right strand gives branches to the inferior ena cava, and the left furnishes the chief fibres of the inferior mesenteric lexus.

The testicular (spermatic) plexus derives its fibres from the renal ad aortic plexuses, and accompanies the testicular artery to the testis, i the female it is called the ovarian plexus, which goes with the artery f that name to the ovary.

The inferior mesenteric plexus is derived chiefly from the left strand f the aortic plexus, and contains a ganglion, called inferior mesenteric, hich lies below the root of the inferior mesenteric artery. The plexus companies the inferior mesenteric artery, and furnishes upper left )lic, lower left colic, and superior rectal plexuses, which supply the sscending colon, pelvic colon, and rectum.

The hypogastric plexus is formed by the fusion of the two halves of ie aortic plexus after these have crossed the common iliac arteries. It reinforced by branches from the lumbar ganglia, and is situated in ont of the body of the fifth lumbar vertebra between the common ac vessels. It is a large flat plexus, measuring about i \ inches in readth, and it ends in two divisions, which become the right and left dvic plexuses.

Coeliac Artery (Coeliac Axis).—The coeliac artery is a short thick trunk hich arises from the front of the aorta between the crura of the aphragm just below the aortic opening. Its direction is forwards id slightly downwards over the superior border of the body of the mcreas, and after a course of about 4 inch it divides into three radiatg branches—left gastric, splenic, and hepatic. Of these the splenic ^the largest, except during foetal life, when it is exceeded by the -patic. The branches of the coeliac artery supply the stomach, ■lodenum, pancreas, spleen, liver, and gall-bladder.

Relations.—The caudate lobe of the liver above, the superior border | body of the pancreas and splenic vein below, the lesser omentum ' J ron l, and a coeliac ganglion on either side. The artery is closely Grounded by the coeliac sympathetic plexus.


The left gastric artery (coronary artery) is directed upwards and

the left as far as the lesser curvature of the stomach on the right s: of the oesophagus. It then, on reaching the bare area at the back the stomach, bends sharply forwards and downwards, and passi between the two layers of the lesser omentum descends in two divisic from left to right along the lesser curvature towards the pylorus, wh it anastomoses with the two divisions of the right gastric branch of 1 hepatic. The artery is surrounded by the superior gastric sympathe plexus.

Branches. —These are oesophageal, cardiac, and gastric. The cesopi geal branches arise when the artery reaches the lesser curvature, a they ascend through the oesophageal opening of the diaphragm anastomose on the gullet with the lower oesophageal branches of t thoracic aorta. The cardiac branches are distributed to the card: end of the stomach, where they anastomose with the short gast branches of the splenic. The gastric branches arise from the t divisions of the artery on the lesser curvature, and pass to the frc and back of the stomach, where they anastomose with branches of t gastro-epiploic arteries.

The left gastric vein ascends from right to left along the les: curvature of the stomach as far as the oesophagus, where it receh a few oesophageal tributaries, after which it turns to the right a opens into the portal vein.

The splenic artery takes a tortuous course to the left along t superior border of the body of the pancreas behind the lesser s; On reaching the front of the left kidney it enters the lieno-renal li£ ment, and breaks up into several splenic branches which enter t spleen through the hilum. The artery is invested by the splenic sy pathetic plexus; the splenic vein lies below it, and behind the pancre

Branches .—These are pancreatic, left gastro-epiploic, short gastr and splenic. The pancreatic branches arise at intervals along t superior border of the pancreas, which they enter. One of the known as the arteria pancreatica magna , enters the organ towai its left end, and passes from left to right, lying a little above the pa creatic duct. The left gastro-epiploic artery arises near the spleen, a passes within the gastro-splenic ligament to the greater curvature of t stomach, along which it descends from left to right between the b layers of the greater omentum as far as the centre, where it anastomoJ with the right gastro-epiploic. It furnishes gastric branches to the fro and back of the stomach, which anastomose with branches of the 1< gastric artery, and epiploic branches, which descend into the greai omentum, these latter being long and slender. The short gash branches arise from the terminal part of the splenic and from its spier branches. They are about five in number, and having passed with the gastro-splenic ligament to the cardiac extremity of the stomac they anastomose with branches of the left gastro-epiploic and k gastric arteries. The splenic branches are about five in number, ai pass to the spleen within the lieno-renal ligament.


The splenic vein is formed by the union of about five veins which nerge from the spleen. It is of large size, and passes from left to ght behind the pancreas near its superior border, where it lies below le splenic artery. Having crossed the aorta, it joins the superior lesenteric vein to form the portal vein behind the neck of the pan•eas. The vein receives the following tributaries: the short gastric, le left gastro-epiploic, many pancreatic veins, and the inferior mesen^ric (as a rule).



Fig. 472. —The Arteries of the Stomach, Liver, and Spleen (after Merkel).


The hepatic artery passes at first to the right along the superior order of the pancreas for a short distance, where it lies behind the

sser sac. It then turns forwards below the opening into lesser sac D the upper border of the first part of the duodenum near the pylorus, od it subsequently ascends between the two layers of the lesser centum in front of the opening into lesser sac towards the porta epatis of the liver, on approaching which it divides into a right and tt hepatic branch. The vessel is accompanied by the hepatic symathetic plexus. As it ascends between the two layers of the lesser






omentum it has the bile-duct on its right side, the portal vein beii behind both.

Branches .—These are right gastric, gastro-duodenal, and right ai left hepatic. The right gastric artery [pyloric artery), of small siz arises near the pylorus, and passes to the lesser curvature of t] stomach, where it divides into two branches. These lie between t] two layers of the lesser omentum, and supply offsets to the front ai back of the stomach. They anastomose with the two divisions of t] left gastric artery. The gastro-duodenal artery also arises near t] pylorus, and descends behind the first part of the duodenum, havii the bile-duct on its right and the portal vein behind it. Havii

reached the lower bord of the first part of tl duodenum, it occupies groove on the right of tl neck of the pancreas, ar here divides into its tv terminal branches—rig] gastro-epiploic and si perior pancreatico-duod nal. The right gastr epiploic artery passes froi right to left along tl greater curvature of tl stomach as far as i centre between the tv layers of the great< omentum, and its distr bution and anastomos< are similar to those of tl left gastro-epiploic arter The superior pancreatic 1 duodenal artery, havir divided into anterior an posterior branches, d< scends between the hea of the pancreas and tf second part of the duodenum, towards the lower end of which latter i anastomoses with the inferior pancreatico-duodenal branches of th superior mesenteric. It supplies the first and second parts of the due denum, and furnishes branches to the adjacent portion of the pancreas The hepatic branches are the terminal divisions of the trunk. The righ which is the larger, enters the porta hepatis at its right end, whilst th left, small in size, enters that porta at its left end, having previous! furnished a branch to the caudate lobe. The right branch gives ol the cystic artery, and this divides into two branches, superior an< inferior, which ramify on the upper and under surfaces of the gall bladder.


Fig. 473.—Plan of the Relations of Portal Vein, Hepatic Artery (HA), and Bile-Ducts Behind the Duodenum (Interrupted Line), and in Lesser Omentum.


RG, right gastric; and SD, supra-duodenal

arteries.


Variations of the Hepatic Artery. —A knowledge of the variations of the right nch of the hepatic artery is of considerable importance, owing to the frency with which operations are performed on the gall-bladder and the biliary sages. The right hepatic artery arises in about 20 per cent, of cases from superior mesenteric artery, while in about 4 per cent, of cases there are sent two right hepatic arteries, one arising from the main hepatic trunk, the er usually from the superior mesenteric artery. While the right hepatic

ry usually passes behind the common hepatic duct, it passes in about 12 per t. of cases in front of it. The cystic artery most usually arises from the it hepatic, the most frequent site of origin being immediately after the artery made its appearance to the right of the duct. Accessory cystic arteries are infrequent. The left hepatic artery may arise from the left gastric artery, s important to remember that *the cystic artery, when it arises from an sual place—which is not very uncommon—always lies anterior to the duct nt).

The pre-pyloric vein passes from left to right, and opens into the tal vein near the pylorus.

The right gastro-epiploic vein passes from left to right, and opens d the superior mesenteric vein near its termination.

The superior pancreatico-duodenal vein takes up blood from the right 1 of the pancreas and from the duodenum, and opens into the superior senteric vein near its termination. Very constantly a small vein

n the pancreatico-duodenal area passes upwards in the greater entum, lying anteriorly near its free margin, and opens into the tal vein.

The cystic vein usually ends in the right division of the portal

n.

All the veins which return the blood from the stomach, duodenum, lcreas, and spleen are destitute of valves, so that the blood can urgitate in cases of portal obstruction.

Coeliac Glands. —The glands of this group are numerous. They round the coeliac axis, and extend over the aorta as low as the T n of the superior mesenteric artery. They receive their afferent sels from the gastric, pancreatic, splenic, and hepatic glands, and ir efferent vessels either join the intestinal lymphatic trunk (or nks) of the superior mesenteric glands, or open independently into

cisterna chyli. Gastric Lymphatic Glands. —These are arranged in two groups, >enor and inferior, the former lying along the lesser curvature of

stomach, and being almost entirely confined to the left part of this 'vature, and the latter below and behind the pyloric canal, forming

subpyloric and retro-pyloric groups. It is noteworthy that there no glands in the neighbourhood of the fundus or along the greater vature until the pylorus is reached. They receive their afferent

'Sels from the stomach, and their efferent vessels pass to the coeliac -nds.

Pancreatic Glands. —These lie along the superior border of the icreas. They receive their afferent vessels from that organ, and their

en t vessels pass to the coeliac glands. Splenic Glands. —These are numerous, and are situated near the


hilum of the spleen in contact with the tail of the pancreas. T! receive their afferent vessels from the spleen, and their efferent vessi having been joined by some of those from the left half of the grea curvature of the stomach, pass to the cceliac glands.

Hepatic Glands. —These are situated between the two layers of 1 lesser omentum near the porta hepatis. They receive as affen vessels those of the deep lymphatics of the liver, which accompany i branches of the portal vein, and also some of the superficial lymphat of the inferior surface of the liver, and their efferent vessels pass to t coeliac glands.

All these glands are closely interconnected through anastomoses betwe their respective afferent and efferent vessels, and so infection of one group liable to be followed by infection of other groups.

Portal Vein. —This vein is formed by the union of the super mesenteric and splenic veins, and is about 3 inches in length, commences on a level with the body of the first lumbar vertel a little to the right of the middle line, where it lies behind the ne of the pancreas. It ascends behind the first part of the duodenu and then between the two layers of the lesser omentum in front the opening into lesser sac, where it has anterior to it the hepa artery and bile-duct, the artery being on the left of the duct. Wh the vessel arrives at the right extremity of the porta hepatis of the In it presents a slight enlargement, called the portal sinus , and then divic into two branches, right and left, the former being the larger a shorter of the two. The right branch, having received the cystic ve enters the right lobe of the liver. The left branch, having traversed t porta hepatis from right to left, and furnished branches to the quadrc and caudate lobes, crosses the fissure for ligamentum teres and enti the left lobe. As it crosses this fissure it is joined in front by t ligamentum teres of the liver, which is the remains of the umbili< vein of foetal life. Posteriorly, and slightly to the right of this poi] it is connected with the fibrous cord which represents the foetal duel venosus. The portal vein near the pylorus receives the prepyloric a left gastric veins. The distinctive character of the vessel is that behaves like an artery, its blood ultimately entering the intralobu] plexuses of the liver.

The sources from which the vein receives its blood are as follow (1) the stomach, (2) the small and large intestine, except a porti of the anal canal, (3) the pancreas, (4) the spleen, and (5) the ga bladder.

Summary of the Tributaries of the Portal Vein. —(1) The superior mesente: vein, which takes up (a) the right gastro-epiploic, ( b ) the pancreatico-duoder veins, ( c ) the jejunal and ileal veins, ( d) the ileo-colic, ( e ) the right colic, a (/) the middle colic. (2) The splenic vein, which takes up (a) the short gast veins, ( b ) the left gastro-epiploic, (c) many pancreatic veins, and ( d ) the infer mesenteric (as a rule), which in turn takes up the superior rectal, lower left col and upper left colic veins. (3) The prepyloric vein. (4) The left gastric ve (5) The cystic vein.


The portal vein and its tributaries are destitute of valves, so that blood can regurgitate in cases of portal obstruction.

Development of the Portal Vein. —-The lower portion of the vein results from union of the two vitelline veins. The upper portion is developed from the half of the lower venous ring and the right half of the upper venous ring, aed by the vitelline veins around the primitive duodenum.

For a description of the bile-duct, see p. 779.


Fig. 474.— The Portal Vein and its Tributaries (after Spalteholz).


Kidneys. —The kidneys are two in number, right and left, and are ^ated deeply at the posterior part of the abdomen, where they lie md the peritoneum. They chiefly occupy portions of the epigastric ^ hypochondriac regions, but also extend slightly into the umbilical ^ lumbar regions. Relatively to the vertebral column they extend u the level of the upper border of the last thoracic vertebra to about centre of the body of the third lumbar, the right kidney being


usually somewhat lower than the left. The long axis of each 01 is directed downwards and slightly outwards, so that their upper c are rather nearer the middle line than the lower. The superior 1 of the right kidney is usually the lower border of the eleventh rib, wl that of the left is usually the upper border of the eleventh rib. feriorly the organs approach the iliac crests, from which they are dis about i to 2 inches, the right being the nearer of the two. Each kid


Fig. 475. — Dissection of the Posterior Abdominal Wall.


is surrounded by a quantity of areolar and adipose tissues, constitut the paranephric fat, which is in turn enclosed by a fibrous tissue covering known as the perirenal capsule (Gerota), and which, along with adjacent viscera, anchors the organ. The capsule is thicker beh than in front, and encloses the suprarenal gland as well as the kidfl The suprarenal gland is attached to the under surface of the diaphra by a strand of fibrous tissue forming a suspensory ligament. Ther no communication or connection between the glands of either side length of a kidney is about 4 inches, the breadth about 2\ inches, d the thickness about i| inches. The right kidney is usually shorter d broader than the fefT. The weight of the organ is about 5 \ ounces, form the kidney is bean-shaped. It presents two smooth surfaces, 0 extremities, and two borders. The anterior surface looks outads as well as forwards, and presents important visceral impressions, lilst the posterior surface looks inwards as well as backwards, and ssents muscular impressions. The extremities are enlarged and and, the superior more so than the inferior, the latter often assuming iomewhat pointed appearance. The lateral border has an inclination ckwards, and is convex and free. The medial border has an inclina


Fig. 476. —The Visceral Areas of the Kidneys. In this case the right renal vein was higher than usual.


n forwards, is concave, and is connected with the renal vessels and s pelvis of the kidney.

Relations — Anterior Surface of the Right Kidney. —This surface is erlapped by the right suprarenal gland for a very short distance at

upper and inner part. It presents three visceral areas—hepatic, odenal, and colic. The hepatic area lies somewhat obliquely, and uipies about the upper two-thirds, being in contact with the renal pression on the under surface of the right lobe of the liver. It is ^ered by peritoneum. The duodenal area corresponds with an elongated rrow strip lying close to the hilum, and reaching a little above and tow it. It is in contact with the posterior wall of the second part of ' duodenum, both being destitute of peritoneum. The colic area 5 below the hepatic, and, like it, is oblique. It is in contact with the



upper end of the ascending colon and the right colic flexure withe the intervention of peritoneum. Between the lower part of the di denal and the colic impressions—that is, at the lower and inner p; of the anterior surface—there is often a small area covered by pi toneum which is in contact with a portion of the small intestine.

Anterior Surface of the Left Kidney. —This surface is overlaps by the left suprarenal gland for a somewhat greater distance at its up] and inner part than obtains on the right side. It presents five visce areas—splenic, gastric, pancreatic, colic, and jejunal. The sple\ area is situated at the upper and outer part close to the lateral bord


Fig. 477. —-Diagram showing the Relations of the Kidneys from Behini


R.L. Right Lung L L. Left Lung S. Spleen

R.K. Right Kidney L.K. Left Kidney IX. Ninth Rib X. Tenth Rib


XI. Eleventh Rib XII. Twelfth Rib

I. L. First Lumbar Vertebra

II. L. Second Lumbar Vertebra

III. L. Third Lumbar Vertebra

IV. L. Fourth Lumbar Vertebra V.L. Fifth Lumbar Vertebra


and is in contact with the renal surface of the spleen, the peritonei of the greater sac intervening. The gastric area , somewhat triangul; lies at the upper end between the splenic and suprarenal areas, and abo the pancreatic area. It is in contact with the postero-inferior surface the stomach, with the intervention of the peritoneum of the small s; The pancreatic area lies transversely below the gastric area, and exten as low as about the centre of the hilum. It is in relation with t posterior surface of the body of the pancreas and the splenic vessi without peritoneum. The colic area is situated at the lower and ou part, and is in contact with the left colic flexure and the commencemii of the descending colon, without peritoneum. # At the lower and ini'


part there is a small area covered by peritoneum, which is related to a rt of the jejunum.

Posterior Surface. —This surface is readily recognized by observing at the pelvis of the kidney is posterior at the hilum. The inner rtion of it rests upon (a) the psoas major and its sheath, and (b) the is of the diaphragm. The outer portion rests, from above downirds, upon (a) the twelfth rib (in the case of the left kidney the venth rib also), (b) the diaphragm, and (c) the quadratus lumborum, vered by the anterior layer of the lumbar fascia. An important rgical relation of the upper part of this division of the posterior rface is that the pleura, in descending between the diaphragm and 3 twelfth rib, lies behind the kidney. Three nerves pass downwards d outwards behind the organ—namely, the subcostal, ilio-hypogastric, d ilio-inguinal. Kidneys hardened in situ usually show impressions educed by the last rib and the transverse processes of the upper nbar vertebrae.

The superior extremity is capped by the suprarenal gland, which also tends for a little over the anterior surface and adjacent portion of 3 medial border.

The lateral border, which is convex, rests on the posterior aponeurosis the transversus abdominis. The lateral border of the right kidney, er about its upper two-thirds, is in contact with the liver, whilst the eral border of the left kidney at its upper end is in contact with the

een. Near this border a small collection of fat is often found which

upies the interval between the kidney and spleen on the left side, d between the kidney and liver on the right side; this fat lies outside 3 fibrous capsule, and has been named the paranephric body to itinguish it from the paranephric fat which lies within the capsule. The medial border of the right kidney lies very near the inferior na cava, whilst that of the left is situated fully 1 inch from the rta. This border is concave, and presents a longitudinal fissure, Ued the hilum, which extends over about its middle third. It ssents two somewhat thick lips, anterior and posterior, and it leads a cavity within the organ, called the renal sinus. It transmits 3 following structures in order from before backwards: the branches the renal vein, the branches of the renal artery, with branches of the ial sympathetic plexus and lymphatics, and the pelvis of the kidney. The side to which a kidney belongs may be ascertained if the uctures at the hilum are in situ by noting that the hilum looks ^ards, that the ureter is posterior and inclines downwards. If, on 5 other hand, the structures at the hilum have been removed, the ^ to which a kidney belongs can usually be easily determined by ting that the anterior lip of the hilum shows two indentations [responding to the two prepelvic branches of the renal artery, [ereas the posterior lip only shows one indentation, which, moreer > points downwards, corresponding to the single retro-pelvic anch of the artery.


Varieties—Form. —The kidneys may be much elongated, or somewhat rou or triangular. The lobulated condition (Fig. 478), which is characteristic the kidney in early life, may persist in the adult.

Size. —One kidney may be diminished in size, in which case there may t proportionate increase in the other organ.

Position. —It is very rare to find the kidneys higher than usual, but on( both not infrequently extend into the iliac fossa, or over the pelvic brim.

Number — Diminution .—One kidney (usually the left) may be entirely s pressed, in which case the solitary kidney usually occupies its normal posit:

and may, or may not, be of large s Increase .—The number may be creased to three, the additional or being lateral or median in position.

Horseshoe Kidney. —This condil is brought about by the fusion of lower parts of the organ, the c necting band of renal substance tending across the vertebral columi Preternatural Mobility. —The kid is usually anchored in its normal p tion by its capsule and the adjac viscera, but it is sometimes mova which may be due to one of 1 causes: (1) the capsule may be v loose, giving rise to the condit known as movable kidney ; or (2) organ may be attached to the poste: abdominal wall by a peritoneal fold, called the meso-nephron, in which case condition known as floating kidney occurs, this being said to be more frequ on the right side.

Movable kidney is more frequent in the female than in the male, a peculiar which has been attributed to the fact that in the female the renal fossae cylindrical, whereas in the male they are pear-shaped, with the narrow end be] (Southam).

For the structure and development of the kidney, see pp. 900 a

910.

Ureter.—The ureter is the excretory duct of the kidney, and conve the urine to the bladder. It is a cylindrical, thick-walled tube, li a goose-quill, its average length being about 12 inches, and its diame about \ inch. The ureter commences towards the lower end of t kidney, where it is the continuation of the pelvis, and terminates in t bladder. The pelvis is funnel-shaped, and flattened from before bac wards. It lies partly in the renal sinus, where it receives the calic and partly outside the hilum, where it lies behind the other transmitt structures. Its direction is downwards and inwards, and, havi: become narrow, it passes into the ureter towards the lower end of t kidney.

The ureter passes downwards and inwards behind the peritoneu in contact with the posterior abdominal wall. It rests at first up< the psoas major and its sheath, being here crossed superficially by t. testicular (or ovarian) vessels, which are taking a course downwar and outwards, and deeply by the genito-femoral nerve, which is taki a similar course. In this part of its course the right duct has the infer! vena cava near it on its inner side, whilst the left duct has the aor



Fig. 478. —Kidney of a Child shortly before Birth.



its inner side, but at some little distance. On the right side the )er end of the ureter lies behind the second part of the duodenum; the left side the ureter is crossed by the upper and lower left colic sels. The ureter next crosses the terminal part of the common iliac sry (or the commencement of the external iliac), after which it ers the pelvic cavity, the right ureter being crossed by the lower t of the root of the mesentery proper, and the left by a portion of pelvic meso-colon, its position here corresponding with that of the ^rsigmoid recess. In the pelvis the ureter first passes downwards,

kwards, and slightly outwards, lying in front of the internal iliac sels and the sacro-iliac joint, following the curvature of the pelvic il in this region. It then turns forwards, downwards, and inwards, lg beneath the peritoneum, and crossing medially the obturator sels and nerve, and the umbilical artery. It subsequently passes rards to the bladder, being crossed medially by the vas deferens, ving arrived at the postero-lateral or ureteric angle of the bladder, it nmences to pierce the vesical wall anterior to the upper free end of the rinal vesicle, being here about 2 inches distant from its fellow, and )ut 1J inches from the base of the prostate gland. It now pursues an ique course through the wall of the bladder, lying in it for about nch, and finally opens into the interior by a very small slit-like jrture placed obliquely at one angle of the base of the trigonum

icse, where it is distant from its fellow and from the urethral orifice )ut ij inches. In the female the ureter, in its pelvic course, passes ng the side of the cervix uteri and upper part of the vagina, being tant f inch from the cervix, and being here crossed antero-laterally the uterine artery.

Varieties. —(1) The pelvis may be absent, its place being taken by two, very rarely three, tubes. (2) Double Ureter. —The foregoing tubes may lain separate for some distance beyond the hilum, or even as low as the bladder, s giving rise to a double or a triple ureter. (3) Dilated Ureter. —This conon is liable to result in consequence of urethral stricture, enlarged prostate, L vesical calculus.

For the structure and development of the ureter, see pp. 907 I 910.

Suprarenal Glands (Suprarenal Capsules). —The suprarenal glands Irenals) are two in number, right and left, and are situated in the gastric region. Each is compressed from before backwards, broad m side to side, and set upon the superior extremity of the corrernding kidney, to which it is bound by connective tissue. Each ^sule encroaches upon the adjacent parts of the anterior surface i medial border of the kidney, the left being mainly situated upon the dial border. The dimensions of the organ are so variable that they 1 only be stated approximately as follows: the length is about ij 'hes, and the breadth rather less than 2 inches. The weight, on an erage, is about 4 grammes, and they are almost as large at birth as later years.

The right suprarenal gland is rather smaller than the left, and is quadrangular. It is pressed between the diaphragm and the post( surface of the right lobe of the liver, and its surfaces are anterior posterior, the former having an inclination outwards and the la inwards. The anterior surface , close to the inner border, is in con with the inferior vena cava, and elsewhere it is related to the poste surface of the right lobe of the liver. At its upper and inner part t is a small fissure, called the hilum, through which the single right su


F!g. 479. —Dissection of the Posterior Abdominal Wall.


renal vein emerges. The peritoneum gives a partial covering to t surface at its lower and outer part. The posterior surface is in conk with the diaphragm and the upper part of the anterior surface of i right kidney. The right coeliac ganglion lies on the inner side of i right gland.

The left suprarenal gland is somewhat semilunar. The anter surface is related above to the postero-inferior surface of the stoma] with the intervention of the lesser sac, which furnishes it with a p<



meal covering. Below this it is related to the posterior surface of the ody of the pancreas and the splenic vessels, without peritoneum, he hilum, through which the left suprarenal vein emerges, is situated t the lower and inner part of this surface. The posterior surface at its pper part is in contact with the left crus of the diaphragm, and below

rests upon The upper and inner part of the front of the left kidney, s well as upon its medial border. Its upper lateral angle is usually in ontact with the apex of the spleen.

For the structure and development of the suprarenal gland, see . 897.

Abdominal Aorta. —The abdominal aorta commences at the aortic pening of the diaphragm on a level with the lower border of the body of he twelfth thoracic vertebra, where it lies in the middle line, and it sually terminates opposite the centre of the body of the fourth lumbar * ertebra, a finger’s breadth to the left of the middle line, by dividing into he right and left common iliac arteries. The position of the bifurcation lay be indicated in one of two ways as follows: (1) by taking a point inch belo\v and to the left of the umbilicus; or (2) by taking a point 1 the line which connects the highest parts of the iliac crests a finger’s •readth to the left of where it intersects the linea alba. The bifurcaion may take place a little lower down or higher up than the normal wel. The length of the vessel is about 5 inches. It occupies the pigastric and umbilical regions, where it lies very deeply behind the •eritoneum, and its direction is downwards with a slight inclination to he left.

Relations — Anterior .—The direct anterior relations, from above lownwards, are as follows: the origins of the phrenic arteries, the oeliac artery, coeliac glands, and cceliac plexus, the ascending layer f the transverse meso-colon, the pancreas and splenic vein, the root I the superior mesenteric artery, the third part of the duodenum nd left renal vein, the origins of the testicular (or ovarian) arteries, he aortic plexus, the pre-aortic group of lumbar glands, the peritoneum »f the greater sac, and the origin of the inferior mesenteric artery, die more remote anterior relations are the lesser omentum, stomach, ransverse colon with its meso-colon, coils of the small intestine, root >f the mesentery proper, and greater omentum. Posterior .—The disc >etween the twelfth thoracic and first lumbar vertebrae, the bodies and liscs of the upper four lumbar vertebrae, and the anterior longitudinal igament, the left lumbar veins, and the origins of the lumbar and nedial sacral arteries. Right .—The right crus of the diaphragm, vith the cisterna chyli and vena azygos lying deeply between the vessel aid the right crus, the cisterna chyli being nearest the aorta, and lightly covered by it; and the inferior vena cava. Left .—The left 'rus of the diaphragm, the left coeliac ganglion, the terminal portion >f the third part of the duodenum, and the left sympathetic gangliated runk.

Branches. —These are nine in number, and are arranged in two Toups, visceral and parietal, four of them being single and five arranged


in pairs. The four single branches are the coeliac artery, super mesenteric, inferior mesenteric, and median sacral. The five pa are the inferior phrenic, middle, suprarenal, renal, testicular (ovari


Fig. 480.—Dissection of Structures on Posterior Wall. Inferior mesenteric artery is laid down (with some of its branches) in positioi


in the female), and the lumbar. Excluding the lumbar arteries, tb order of origin of the branches is as follows: (1) phrenic, (2) coelia artery, (3) superior mesenteric and (4) middle suprarenal, both 0 the same level, (5) renal, (6) testicular (or ovarian), (7) inferior meser



c, and (8) median sacral. In what follows, the letter P after an sry signifies parietal, and V visceral.

The phrenic arteries (P) are two in number, right and left. They se, either separately or by a common trunk, from the front of the ta, as soon as the vessel has passed through the aortic opening of diaphragm. They at once diverge, each passing outwards and vards over the crus of the diaphragm, the right vessel lying behind inferior vena cava, and the left behind the oesophagus. Each ends dividing into two branches, medial and lateral. The medial branch ises forwards and inwards in a curved manner in front of the central don, and anastomoses with its fellow of the opposite side, and the sculo-phrenic of the internal mammary. The lateral branch passes wards, and anastomoses with the musculo-phrenic and the lower srcostal arteries. Each phrenic artery furnishes a superior supraal branch (or branches) to the suprarenal gland, the right vessel d giving off a few branches to the inferior vena cava, whilst the

supplies a few branches to the oesophagus. The right phrenic vein opens into the inferior vena cava, and the terminates in the left suprarenal vein, left renal vein, or inferior 1a cava.

The cceliac artery (V) and superior mesenteric artery (V) will be ind described on pp. 811 and 796.

The middle suprarenal arteries (V) are of small size, and are two in mber, right and left, each arising from the side of the aorta on a el with the origin of the superior mesenteric artery. The vessel sses outwards and upwards over the crus of the diaphragm to the Drarenal gland, in which it anastomoses with the superior suprarenal the phrenic and the inferior suprarenal of the renal.

The right suprarenal vein opens into the inferior vena cava, and the t into the left renal vein.

The suprarenal veins originally open mainly into the subcardinal system, e right suprarenal vein thus opens into the upper segment of the inferior 1a cava (above the right renal vein). The left suprarenal vein, as the remnant the left subcardinal vein, joins the left renal vein.

The renal arteries (V) are remarkable for their large size, and are 0 in number, right and left. They arise from the side of the aorta out \ inch below the superior mesenteric on a level with the body the first lumbar vertebra, the right artery being usually a little ver than the left. They form right angles with the aorta, and cross 3 crura of the diaphragm on their way to the hila of the kidneys, e right vessel passing behind the inferior vena cava, second part of e duodenum, and head of the pancreas, whilst the left passes behind e body of the pancreas. Each vessel has its own vein in front of it, d the aortico-renal ganglion lies over its root. On approaching the lal hilum each vessel divides into three or four branches, one of which, town as the retro-pelvic branch, usually passes behind the pelvis of e kidney, whilst the others lie between the renal vein in front and the pelvis behind. For the subsequent distribution of the branches the kidney, see p. 904.

Before breaking up into its proper renal branches the vessel g] off an inferior suprarenal artery to the suprarenal gland, paranep , branches to the capsule, and ureteric to the upper part of the ureter

Varieties. —(1) Very often there is an accessory renal artery present, ari close to the main vessel, and usually above it. (2) The renal artery may di 1 into its renal branches close to its origin. (3) There may be an aberrant r artery, which may arise from the phrenic, testicular (or ovarian), inferior mesenteric, common or external iliac, or median sacral. An aberrant renal arte when present, is usually confined to one side, more frequently the right; 1 artery more often passes behind the ureter than in front (Hutchinson). (4) cases of variations, or even in the normal condition, one or more of the rei branches may fail to enter the hilum, and may pierce the kidney on its anter surface, or near the upper or lower end.


Fig. 481.—To show the Arrangement of Veins joining to form the Portal Vein, and their Relations to the Aorta.



The renal veins, like the arteries, are of large size. Each lies front of its artery, and receives tributaries from the paranephric i and the upper part of the ureter. The vessels are tributaries of t inferior vena cava, which they join almost at a right angle, the k




ittle higher than the right. The left vein crosses in front of the ta, taking up in its course the left suprarenal and left testicular ovarian) veins. In some cases there is a single semilunar valve at

lower part of the opening of each renal vein into the inferior vena r a.

The renal veins originally join the periganglionic veins. Subsequently the it renal vein opens into the junction of the upper and lower segments of the

rior vena cava. When the left cardinal vein becomes obliterated, in great t the left renal vein becomes continuous with the primitive inferior vena cava.

mesial portion of the left renal vein is developed from the pre-aortic venous ms. For details see Chapter XIII.

The testicular arteries (spermatic arteries) (V) are two in number, ht and left, and they arise from the front of the aorta about 1 inch ow the renal arteries. If they arise separately they are close to each ler, but they sometimes spring by a common trunk. They are long, nder, somewhat tortuous vessels, which at once diverge, each passing iquely downwards and outwards behind the peritoneum. In this irse the vessel rests upon the aorta for a short distance, and then on the psoas major and its sheath, where it crosses the ureter, e right artery passes in front of the inferior vena cava and behind i terminal part of the ileum, whilst the left passes behind the left ic vessels and the iliac part of descending colon. Subsequently the

ery, on its way to the deep inguinal ring, lies upon the terminal part the external iliac. At the deep ring it approaches the vas deferens form, with other structures, the spermatic cord. The vessel then sses through the deep inguinal ring, along the inguinal canal, and rough the superficial inguinal ring into the scrotum, where it divides

o glandular and epididymal branches. In the abdomen the testicular ery furnishes ureteric branches to the ureter, and in the scrotum skives off cremasteric branches to the coverings of the spermatic cord, rich anastomose with the cremasteric branch of the inferior epigastric, iring foetal life the vessel is very short, and takes a transverse course the testis, which is then lying near the kidney. As the testis, hower, descends into the scrotum the vessel gradually becomes much rngated.

Varieties. —(1) One or both testicular arteries may be absent, in which cases

testis is supplied chiefly by the artery to the vas deferens. (2) A testicular ery may arise from a renal artery. The testicular veins (spermatic veins) spring from the pampiniform 2 xus of the spermatic cord at the deep inguinal ring, and are at first r o in number on each side, which lie one on either side of the correonding artery. They subsequently unite to form a single vessel, rich on the right side opens at an acute angle into the inferior vena va, and on the left at a right angle into the left renal vein. There is ually a valve at the point of termination of each vein, though this ay be absent. In the left testicular vein, where it joins the left renal

in, the valve directs the current of blood entering by the testicular in in the direction of the inferior vena cava. It also prevents the blood in the left renal vein from entering the testicular vein by direc the current over the mouth of the latter vessel. The left testici vein is rather longer than the right.

The testicular (or ovarian) veins drain the embryonic gonad into the cardinal venous system. Part of the abdominal vena cava (Chapter XII) is veloped from the subcardinal vein, so that the right testicular vein opens into ■ On the left side the subcardinal system drains by pre-aortic anastomosis the right subcardinal (inferior vena cava), the anastomosis forming part of left renal vein; hence the left testicular vein or ovarian vein opens into the renal vein.

The ovarian arteries (V) in the female take the place of the testici arteries in the male, and their course and relations in the abdor correspond with those of the testiculars. The ovarian arteries ; however, shorter than the testiculars, and they do not pass out throi the inguinal canal, but enter the pelvis by crossing the commencem of the external iliac artery. In the pelvis each vessel becomes v tortuous, and passes between the two layers of the broad ligamen the uterus to be distributed to the ovary. In the abdomen the art supplies branches to the ureter, and in the pelvis it furnishes the folli ing offsets: tubal to the uterine tube; a uterine branch to the side of uterus; and a ligamentous branch to the ligamentum teres of the utei which it accompanies as far as the inguinal canal. The ovarian arter like the testicular, are very short and transverse in direction dur foetal life, when the ovary occupies a position similar to that of testis. They, however, gradually become elongated as the ov; descends to its future abode in the pelvis.

The ovarian veins spring from the ovarian or pampiniform pie: between the two layers of the broad ligament close to the ovary. A 1 emerging therefrom their subsequent course and mode of terminat resemble those of the testicular veins.

For the inferior mesenteric artery (V) and vein, see p. 801; the median sacral artery (P) and vein, see p. 946; and for the lum' arteries (P) and veins, see p. 847.

Inferior Vena Cava. —The inferior vena cava commences oppos the upper border of the body of the fifth lumbar vertebra a little the right of the middle line, where it is formed by the union of 1 right and left common iliac veins, and it terminates at the poste inferior angle of the right atrium of the heart. It ascends along 1 right side of the aorta, resting upon the anterior and right aspects the lumbar vertebrae as high as the level of the second. Beyond t point it diverges from the aorta, and is supported by the right cj of the diaphragm. It then occupies the fossa for vena cava on 1 posterior surface of the right lobe of the liver. On leaving this fossa passes through the caval opening in the central tendon of the diaphrag and almost immediately afterwards opens into the postero-infer angle of the right atrium of the heart. As the vein passes through i caval opening, its walls are connected with the margins of that openii and so the patency of the vessel is maintained.


Relations — Anterior .—From below upwards, the right common c artery, lower part of the root of the mesentery proper, right ticular (or ovarian) vessels, third part of the duodenum, head of

pancreas, origin of the portal vein, first part of the duodenum, ming into lesser sac, and posterior surface of the liver. Posterior .— e bodies, discs, and anterior longitudinal ligament of the lower three ibar vertebras, the corresponding right lumbar vessels, inner border


ug. 482. —Scheme of the Inferior Vena Cava and its Tributaries.

the right psoas major and its sheath, right sympathetic gangliated ink, right renal artery, right coeliac ganglion, right crus of the diaragm, right suprarenal gland, and right phrenic artery. Right .— 3 m below upwards, the right ureter and the medial border of the ht kidney. Left .—From below upwards, the aorta and the right is of the diaphragm.

Tributaries. —These are as follows: the right and left common •c veins, right and left lumbar veins, the right testicular (or ovarian)







vein, the right and left renal veins, the right suprarenal vein, the ri^ phrenic vein (and sometimes the left), and the hepatic veins at i fossa for vena cava of the liver.

Chief Varieties. —(1) The vessel may be found on the left side of the ao: in its lower part, in which cases it subsequently crosses that vessel to take its usual position on its right side. This may be due to a transposition of visce or to a permanent patency of the lower part of the left cardinal vein of foetal li (2) The two common iliac veins, instead of uniting at the level of the fifth luml vertebra, may run up on either side of the aorta until they have received th renal tributaries, after which the left crosses the aorta to join the right, a form the inferior vena cava about the level of the first lumbar vertebra. (3) T. inferior vena cava in very rare cases may terminate in a large azygos vein, a through means of that in the superior vena cava. Under these circumstam the hepatic veins open into the right auricle of the heart.

Development .—The postrenal segment of the inferior vena cava is develop from the lower portion of the right supracardinal or periganglionic veins. 1 prerenal segment is developed from (1) the upper portion of the right subcardii vein; (2) the hepatic sinusoids; and (3) the common hepatic vein (Lewis). £ development of vessels, in Chapter XIII.

Aortic Lymphatic Glands. —These glands are very numerous, ai are arranged in four groups , which lie around the abdominal aori The groups are spoken of as pre-aortic, juxta-aortic, right and left, a] retro-aortic, respectively.

Pre-aortic Glands. —These are usually disposed in three setsnamely, (1) cceliac glands, which constitute a very distinct set aroui the origin of the coeliac artery; (2) superior mesenteric glands, in tl region of the origin of the superior mesenteric artery, and along t] trunk of the vessel; and (3) inferior mesenteric glands,in the region the origin of the inferior mesenteric artery.

The afferent vessels of the pre-aortic glands are derived from the following sources:

  1. Rectum.
  2. Pelvic colon.
  3. Descending colon.
  4. Transverse colon.
  5. Ascending colon.
  6. Caecum.
  7. Vermiform appendix.
  8. Small intestine.
  9. Stomach.
  10. Liver.
  11. Pancreas.
  12. Spleen, glands.
  13. Juxta-aortic

The coeliac glands more particularly receive their chief afferent vessels from the following glands:

  1. Gastric glands.
  2. Retro-pyloric glands.
  3. Hepatic glands.
  4. Splenic glands.
  5. Pancreatic glands.


The efferent vessels of the pre-aortic glands usually unite to fori one trunk, called the intestinal lymphatic trunk, which with the lumbc lymphatic trunks from the juxta-aortic glands forms the cisterna chyl A few of them pass to the retro-aortic glands.


Tuxta-aortic Glands (Lateral Lumbar Glands). —These are disposed wo groups— right and left. The right glands lie both in front of, behind, the inferior vena cava, whilst the glands of the left side n a single chain on the left side of the abdominal aorta, rhe juxta-aortic glands of either side receive their afferent vessels a the following sources:

  1. Common iliac glands.
  2. Testis. 5. Kidney.
  3. Ovary, uterine tube, and adjacent half of body of uterus.
  4. Suprarenal gland.
  5. Kidney.
  6. Abdominal wall.


rheir efferent vessels for the most part unite on either side to form mbar lymphatic trunk, right and left, which opens into or forms the -rna chyli. Some pass to the pre-aortic glands, and others to the o-aortic glands.

Retro-aortic Glands. —These glands are about four in number, and j lie behind the abdominal aorta in front of the bodies of the third fourth lumbar vertebrae. Their afferent vessels are derived from pre-aortic and lateral aortic glands, as well as from the vertebral ies and ligaments to which they are related. Their efferent vessels

e to form a single trunk, called the intestinal lymphatic trunk , which is into the cisterna chyli.

Diaphragm — Origin. — Sternal Portion. —By two fleshy slips from back of the xiphoid process close to its lower end. Costal Portion.— six fleshy slips at either side from the inner surfaces of the lower costal cartilages, which interdigitate with slips of the transversus ominis. Lumbar Portion.— From the lateral and medial arcuate nents, and from the anterior surfaces of the bodies of lumbar ebrae, as well as the intervertebral discs and anterior longitudinal nent, by two crura, the right crus reaching usually as low as the between the third and fourth lumbar bodies, and the left as low as disc between the second and third.

T nsertion. —The central tendon on all sides.

V erve-supply .—The right and left phrenic nerves, each of which figs chiefly from the anterior primary division of the fourth cervical r e, and usually receives a branch from the fifth, and sometimes from third. Each phrenic nerve, on approaching the diaphragm, des into a dorsal and two ventral branches, the dorsal branch being ributed to the lumbar portion, the two ventral branches accomping the two branches of the phrenic artery. On the right side, re a communication takes place between the right phrenic nerve and right phrenic sympathetic plexus, a small ganglion, called the \lion diaphragmaticum, is situated at the place of communication, milar connection is established on the left side, but no ganglion is ent.

Arterial Supply. —(1) The phrenic branches of the abdominal (2) the pericardiaco-phrenic and musculo-phrenic, both branches be internal mammary of each side; (3) the phrenic branch of the


superior epigastric of the internal mammary of each side; and (4) bram from the lower intercostal arteries.

Lymphatics .—These are arranged in two groups, one on the thor; aspect, the other on the abdominal aspect; there is a free communicai between the two groups on each side of the middle line, but not so : between the groups of the two sides. The free communication refei to is promoted by the movements of respiration, for during inspirat when the pressure in the thorax is reduced, and that in the abdoi is increased, the lymph flows from the abdominal to the thor surface of the diaphragm, while during expiration the movemen reversed. The lymph is drained from the diaphragm superiorly by


Fig. 483. —The Diaphragm (Inferior View).


supradiaphragmatic glands, which send their efferents to the intei mammary, posterior mediastinal, and intercostal glands, and from diaphragm inferiorly by the upper juxta-aortic glands of either si the pre-aortic and oesophageal glands. The lymphatics of the vari viscera in relation with the diaphragm are separate from those of diaphragm except in the case of the liver.

Action .—The diaphragm by its contraction increases the vert] diameter of each half of the thorax, and is therefore a muscle of spiration. The middle portion of the central tendon is fixed by rea: of the fibrous portion of the pericardium, which is implanted into being connected above with the deep cervical fascia. The fle;







rtion, however, becomes flattened, and descends towards the abdomen, placing the viscera, and so increasing the vertical diameter of each If of the thorax. The diaphragm also elevates the lower ribs, except

last, which is fixed by the quadratus lumborum muscle. The muscular fibres pass in an arched manner upwards and inwards to the Aral tendon, upon which they converge from all points. The sternal portion separated on either side from the costal portion by a small interval occupied areolar tissue, through which the superior epigastric vessels and some of the •erficial lymphatics of the upper surface of the liver pass. Above and below 3 interval are the pleura and peritoneum respectively. In this situation a phragmatic hernia may take place, involving one or other of the abdominal cera. Between the lowest costal fibres of the corresponding lateral arcuate iment there is sometimes another areolar interval of small size. The crura strong, thick, musculo-tendinous bundles disposed vertically, the left being

smaller, shorter, and more posterior of the two. Each crus is fleshy laterally, 1 strongly tendinous medially, the lower extremity of each being entirely idinous. On a level with the lower border of the body of the twelfth thoracic •tebra the inner tendinous fibres of the crura are connected by a fibrous band, led the median arcuate ligament, which lies in front of the aorta. The muscular res of the crura pass upwards in a diverging manner to be inserted into the iterior border of the central tendon. The innermost muscular fibres on either e, reinforced by fibres springing from the median arcuate ligament, decussate ore reaching the central tendon, and enclose between them the oesophageal ming. In the decussation the bundle derived from the right crus passes in nt of that from the left, which latter is of small size.


The central tendon is also called the cor diform or trefoil tendon, is much elongated from side to side, convex in front, and conve behind. It is divided into three lobes or alse—right, median, d left, of which the right is the largest, and the left the smallest d narrowest.

The diaphragm presents three foramina—namely, aortic, vena val, and oesophageal.

The aortic opening is situated in the middle line between the upper rtions of the crura, and in front of the disc between the bodies of e twelfth thoracic and first lumbar vertebrae. It is bounded on her side by a crus, in front by the median arcuate ligament, and hind by the anterior longitudinal ligament of the vertebral column, is therefore not really an opening in the diaphragm, but is situated hind it. It transmits the aorta, thoracic duct, and azygos vein, in is order from left to right.

The vena caval opening is situated in the central tendon close to its sterior border and at the junction of the right and median lobes, is somewhat four-sided, with rounded angles, and transmits the ferior vena cava, twigs from the right phrenic nerve, and some of e deep lymphatics of the liver.

The oesophageal opening is situated in the fleshy-part of the muscle, is elliptical, and lies in front, and a little to the left, of the aortic 'ening, being separated from it behind by the inner decussating >res of the crura. It transmits the oesophagus, the right and left gus nerves, and the oesophageal branches of the left gastric


In addition to the foregoing foramina, the diaphragm presents certain sr fissures as follows: each crus is pierced by the greater and lesser splanct nerves, and sometimes by the lowest. The left crus is also pierced by the infe vena hemiazygos vein. The musculo-phrenic artery pierces the costal port and the branches of the phrenic nerve are also transmitted through the mus A small vein pierces the central aponeurosis on the left side at a point co sponding to that of the vena caval opening on the right side; it is believed represent the left vitelline vein of the embryo.

The arcuate ligaments are five in number, as follows: lateral, rij and left; medial, right and left; and median. The lateral arcu ligament is a thickening of the upper part of the anterior wall of sheath of the quadratus lumborum, and extends from the last to the tip of the transverse process of the first lumbar vertebra. 1 subcostal artery and anterior primary division of the last thora



Fig. 484.— The Diaphragm (Superior View) (after L. Testut’s ‘ Anatomie Humaine ’).

nerve pass downwards and outwards behind it. The medial arcui ligament is a thickening of the upper part of the sheath of the psc major, and extends from the tip of the transverse process of the fi lumbar vertebra to the side of its body, and sometimes to that of 1 second vertebra. The gangliated trunk of the sympathetic pas: into the abdomen behind it, and sometimes the lowest splanchnic ner The median arcuate ligament is a fibrous band which connects t innermost tendinous fibres of the crura on a level with the lower bore of the body of the twelfth thoracic vertebra, and arches over the aort

Relations of the Diaphragm — Superior .—The right and left pleurae with lungs, and the pericardium with the heart. Inferior .—The peritoneum, exo opposite the bare area of the posterior surface of the liver; the liver with j falciform, coronary, and right and left triangular ligaments; the stomach; spiel! pancreas; kidneys; and suprarenal glands.


Development. — The diaphragm is developed in four parts—ventral and dorsal l lateral (R. and L.).

The ventral part, central, is the first to appear, and is developed from the turn transversum. It lies between the pericardial and peritoneal cavities, l has the primitive oesophagus passing on its dorsal aspect in the mid-line, with ericardio-peritoneal passage on each side of this ; these are the primitive pleural



Fig. 485. — The Thoracic Duct, Azygos Veins, and Posterior Intercostal Glands.

hes, from which the secondary pleurae will start their extension into the 7-wall.

iach of the lateral parts is brought into existence as the result of extension of sural sac. This, enlarging in the body-wall, splits this into inner and outer rs. The extension of the cavity caudally brings the inner layer into evidence Fe pleuroperitoneal membrane, separating the growing pleura from the ttnmal cavity. Extension of muscle cells from the central part into these




lateral membranes makes them into the lateral portions of the diaphragm, fusion between these pleuro-peritoneal membranes and the ventral part o diaphragm may be incomplete on one or other side, in which cases a commu tion is left between the thoracic and abdominal cavities, through which a phragmatic hernia may occur. The persistent opening is just lateral to the si renal gland.

The central dorsal part of the diaphragm is formed from the common d mesentery, or meso-oesophagus (see p. 61), into which muscular fibres ex to form the crura.


Gangliated Trunk of the Sympathetic. —This cord enters the al men behind the inner portion of the medial arcuate ligament. It i descends along the inner border of the psoas major, where it lie front of the bodies of the lumbar vertebrae, and having passed be] the common iliac artery, it enters the pelvis. The right lumbar tr is under cover of the inferior vena cava, whilst the left lies a little tc left of the aorta, and the lumbar vessels of each side pass beneath corresponding cord. Each cord usually possesses four ganglia.

Branches. —These are arranged in two sets—namely, rami c municantes, and branches of distribution. The rami communicai which are long, are of two kinds, white and grey, the latter b

the more numerous. The u rami are composed of me< lated nerve-fibres, and are more than three in num They are derived from anterior primary division: the first two or possibly tl lumbar nerves, and procee< the ganglia. The grey r pass from all four ganglia join the anterior primary d sions of the five lumbar ner One or more rami may div and so pass to one or ir ganglia. Both white and g rami pass together bene the fibrous arches of the ps Fig. 485A.— Two Common Modes of Origin major in company with of the Thoracic Duct (after Rouviere). lumbar vessels, and the C(

L, lumbar ducts; I, intestinal duct. In one case there is a definite cisterna (C). Some juxta-aortic glands are seen below.



munications with the lum nerves are established d to the intervertebral forami The branches of distribul proceed partly from the ganglia and partly from the connecting cc and are distributed to the coats of the aorta, the bodies and ligame of the lumbar vertebrae, and the hypogastric plexus, the last branc crossing the common iliac artery.

Cisterna Chyli (Receptaculum Chyli). —This is the dilated commer ment of the thoracic duct. It is situated deeply at the upper pari

posterior abdominal wall in front of the bodies of the first and second bar vertebrae, where it has the aorta on its left side and slightly in t, and the vena azygos on its right side. It is overlapped by the t crus of the diaphragm. It is somewhat elliptical, being about

h broad at its widest part, and about 2 inches in length. Superiorly ccomes narrow, and is continued into the thoracic duct, which

rs the thorax through the aortic opening of the diaphragm. It ives the following efferent vessels from below upwards: the right left lumbar lymphatic trunks from the juxta-aortic glands, which its lower narrow end; the efferent vessels from the retro-aortic ids; and the intestinal lymphatic trunk (or trunks) from the preic glands.

fVzygos Veins. —These are three in number—namely, the vena

os, the inferior vena hemiazygos, and the superior vena hemi*os. rhe vena azygos usually commences in the right ascending lumbar , which is formed by longitudinal anastomosing branches passing veen the lumbar veins in front of the lumbar transverse processes, so disposed as to form one vein which communicates with the rior vena cava, and with one or other of the following veins of the t side: the common iliac, the internal iliac, the ilio-lumbar, or the ral sacral. Sometimes, however, the azygos vein springs from the

erior aspect of the inferior vena cava close to the right renal vein, rom that renal vein itself, or from the first right lumbar vein. It

nds upon the body of the first lumbar vertebra, where it lies on the it side of the cisterna chyli under cover of the right crus of the )hragm, and it enters the thorax through the aortic opening of t muscle. For its subsequent course in the thorax, where it ninates in the superior vena cava, see the section of the thorax. The inferior vena hemiazygos commences in the left ascending bar vein, through which it has communications similar to those he azygos vein. It may, moreover, spring from the left renal vein, he first left lumbar vein. It enters the thorax through the left crus he diaphragm, and subsequently terminates in the azygos vein.

The azygos and inferior hemiazygos veins are persistent portions of right and left cardinal veins of foetal life.

The azygos and inferior hemiazygos veins, through their connections h the ascending lumbar veins, establish communications with the

rior vena cava, and with the common iliac veins or some of their •utaries. They therefore form important channels by which a siderable quantity of blood is returned from the lower limbs and Lominal wall in cases of obstruction of the inferior vena cava.

The superior vena hemiazygos will be found described in connection h the thorax.

Fasciae of the Posterior Abdominal Wall—Iliac Fascia. —This fascia ers the iliacus and psoas major muscles. Above the level of the c crest it is related only to the psoas major, and the part covering t muscle is spoken of as the psoas sheath. Superiorly it forms the


medial arcuate ligament, which extends between the tip of the lumbar transverse process and the side of the body of that verte Medially it is attached to {a) the intervertebral discs and contigi margins of the bodies of the lumbar vertebrae, and (b) the fibrous ar over the lumbar vessels opposite the centre of each lumbar b< Laterally , near the tips of the lumbar transverse processes, it ble with the anterior layer of the lumbar fascia which covers the quadr; lumborum. Below the level of the iliac crest the iliac fascia covers iliacus as well as the psoas major. This part of it is known as fascia iliaca , and it passes uninterruptedly from the iliacus on to psoas major. Laterally it is attached to the anterior two-thirds of iliac crest immediately within its inner lip, and 'medially to the al the sacrum and the iliac portion of the pectineal line. Inferiorl is disposed in the following manner: along the outer half of the ingu ligament on its deep aspect the fascia is firmly attached to that 1 ment, and joins the fascia transversalis, the two constructing a a which contains the first part of the deep circumflex iliac artery, posite the external iliac vessels the fascia passes downwards bet them and the inguinal ligament to form the posterior wall of the fern* sheath. Medial to the external iliac vessels it is continuous with pubic lamina of the fascia lata, as that covers the upper part of pectineus. From the point of junction between the iliac fascia and pubic fascia lata an intermuscular septum (ilio-pectineal) passes bs wards between the pectineus and the psoas major to be attached to ilio-pubic eminence and the front of the capsular ligament of the 1 joint.

The importance of the iliac fascia has reference to the course taken by in cases of lumbar (psoas) abscess. The pus cannot pass outwards over quadratus lumborum without bursting through the psoas sheath, because psoas sheath is bound down to the anterior wall of the fascia covering quadratus lumborum at the outer border of the psoas muscle. It cannot ] across the vertebral column on account of the attachments of the psoas she in that situation. The usual course, therefore, taken by the pus is to dif itself downwards within the psoas sheath. On reaching the iliac fossa it 1 diffuse outwards beneath the iliac fascia as that covers the iliacus muscle, br cannot enter the pelvic cavity on account of the attachment of the iliac fa to the pelvic brim, unless it bursts through the psoas sheath. Consequen the pus usually treks along the psoas major within its sheath, and, pas: behind the inguinal ligament and the femoral sheath containing the fem vessels, it may point in the region of the saphenous opening on a level with lesser trochanter, simulating a femoral hernia, or it may accompany one or ol of the large vessels in this region, more particularly perhaps the medial fem' circumflex artery, which may conduct it to the back and inner side of the th

Lumbar Fascia (Aponeurosis). —This is situated between the ] rib and the iliac crest, and is often regarded as the posterior aponeurc of the transversus abdominis muscle. Strictly speaking, only middle layer is the posterior aponeurosis of this muscle. When follo\ backwards it divides into three layers—anterior, middle, and poster: The anterior layer, which is thin, covers the quadratus lumbort and is attached medially to a vertical ridge on the anterior surface

e transverse processes of the lumbar vertebrae some distance medial their tips. In this situation it is interposed between the quadratus mborum and psoas major, and receives the iliac fascia which forms e psoas sheath. At the outer border of the quadratus lumborum it ins the middle layer, and is here also continuous with the fascia transTsalis. Superiorly it forms the lateral arcuate ligament, which tends between the last rib and the tip of the first lumbar transverse ocess. Interiorly it is attached to the ilio-lumbar ligament and the ntiguous part of the inner lip of the iliac crest. The middle layer, tiich is of considerable strength, is attached medially to the tips of e lumbar transverse processes, and laterally, at the outer border of e quadratus lumborum, it is joined by the anterior lamina, whilst the outer border of the sacro-spinalis it receives the posterior layer.


Fig. 486. —Diagram of the Lumbar Fascia.

iperiorly it is attached to the lower border of the last rib, and inriorly to the back part of the summit of the iliac crest. The middle yer lies between the quadratus lumborum and the sacro-spinalis. ie posterior layer, which is also very strong, is attached to the spinous ocesses of the lumbar and sacral vertebrae, and the posterior fourth the outer lip of the iliac crest. It lies behind the sacro-spinalis, at the her border of which it blends with the middle layer, and so the uscle is enclosed in a sheath. The posterior layer is joined by the scia covering the latissimus dorsi, and affords attachment to the tter muscle and serratus posterior inferior.

Muscles of the Posterior Abdominal Wall—Psoas Major (Magnus)— 'igin. —(1) The inner part of the anterior surface of the transverse ocesses of the lumbar vertebrae; (2) the lateral aspects of the intervertebral discs, and of the adjacent borders of the twelfth thorac and all the lumbar vertebrae; and (3) a series of fibrous arches whi cross the lumbar vessels at the centres of the bodies of the lumb vertebrae.

Insertion .—The lesser trochanter of the femur, by a tendon whi receives on its outer side the greater part of the iliacus.

Nerve-supply .—The lumbar plexus. The branches come me particularly from the anterior primary divisions of the second ai third lumbar nerves.

Action .—Acting from its origin, the muscle is a powerful flexor the thigh upon the pelvis, coming into play in walking, or ascendi a stair; it is a weak medial rotator of the hip. Acting from its i sertion, it is a flexor of the lumbar portion of the vertebral colun upon the pelvis, and of the pelvis upon the thigh, as in the act of stoo ing. The muscle of one side, acting from its insertion, is capable producing lateral flexion of the lumbar portion of the vertebral colum

As the muscle descends close to the pelvic brim the fibres of t iliacus begin to join the outer side of its tendon, and they contin to do so as far as the insertion, thus giving rise to a conjoined mus( known as the ilio-psoas.

Psoas Minor (Parvus). —This muscle is present in man on one or both sic in about 45 per cent, of bodies. It arises from the lateral aspect of the inti vertebral disc between the twelfth thoracic and first lumbar vertebrae, and fre the contiguous borders of their bodies, by means of a small fleshy belly, which usually about 2 inches long. It is then replaced by a long, narrow, flat tendc which expands as it is about to take insertion into the middle of the pectin* line and the ilio-pubic eminence, in which latter situation it blends with the il pectineal intermuscular septum. It also gives an aponeurotic expansion to t whole length of the inguinal ligament.

The nerve-supply is the anterior primary division of the first lumbar nen Acting from its origin, the muscle tends to flex the pelvis upon the vertebi column, and is a tensor of the psoas sheath. Acting from its insertion, it ten to flex the lumbar portion and lower part of the thoracic portion of the vertebi column upon the pelvis. Its characteristic action is seen in the position assum by saltatory animals preparatory to the act of leaping, that position consisti in a drawing forwards of the pelvis and vertebral column.

The psoas minor lies along the anterior aspect of the psoas major close to inner border, except at the pelvic brim, where its expanded tendon turns to t inner side of that muscle.

Iliacus — Origin. — (1) The lateral part of the upper surface of the a of the sacrum; (2) the anterior sacro-iliac, ilio-lumbar, and lumb sacral ligaments; and (3) the upper half of the iliac fossa, reachii anteriorly as low as the anterior inferior iliac spine.

Insertion. —(1) The outer aspect of the tendon of the psoas majo (2) the triangular surface which is situated below, and in front c the lesser trochanter of the femur (between it and the spiral line and (3) the ilio-femoral ligament. The fibres inserted into the ili femoral ligament are those which arise in the region of the anterior i ferior iliac spine. They are sometimes separated from the rest of tj muscle, and are then known as the ilio-capsularis.


Nerve-supply .—The femoral nerve.

Action .—Acting from its origin, the muscle is a flexor of the thigh pon the pelvis. Acting from its insertion, it is a flexor of the pelvis pon the thigh.

Quadratus Lumborum — Origin. —(1) The ilio-lumbar ligament;

) the inner lip of the crest of the ilium for about 2 inches behind id outside the ilio-lumbar ligament; and (3) the tips of the transverse rocesses of the lower three or four lumbar vertebrae.

Insertion. — (1) The lower border of the last rib along its inner half, id (2) the tips of the transverse processes of the upper three or four


Fig. 487.—The Psoas, Iliacus, and Quadratus Lumborum Muscles.

imbar vertebrae, by tendinous slips which lie behind the slips of origin, he fibres of the muscle are so arranged as to form deep and supernal layers; the deep layer consists of ilio-transverse fibres, the supercial layer of transverso-costal fibres medianly and of ilio-costal fibres derally.

Nerve-supply .—The subcostal nerve and the anterior primary l visions of the first two lumbar nerves.

Action .-—Acting from its origin, the muscle depresses and fixes le . last rib, and is therefore a muscle of inspiration, inasmuch as ls auxiliary to the diaphragm. In depressing the last rib the






muscle is also capable of producing lateral flexion of the vertebi column. Acting from the last rib, it will produce lateral flexion the pelvis.

The muscle is encased in a sheath, the anterior wall of which formed by the anterior layer of the lumbar fascia, and the posteri wall by the middle layer.

Lumbar Plexus. —The lumbar plexus is situated deeply in front the transverse processes of the first three lumbar vertebrae in the su stance of the psoas major. It is formed by the anterior prima divisions of the first three lumbar nerves and the greater part of th

of the fourth. In addition, ti anterior primary division of the fir lumbar is usually reinforced by small communicating branch fro the subcostal nerve, called the dors lumbar nerve. The nerves concern! in the lumbar plexus first furnish tl following branches: (i) the first giv twigs to the psoas minor when pre ent; (2) the first and second supp branches to the quadratus lur borum; (3) the second and thii give branches to the psoas majo and (4) the upper two or three fu nish white rami communicantes 1 the lumbar sympathetic gangliate trunk. The mode of formation ar branches of the plexus are as follow the first lumbar, having been, as rule, reinforced by the dorso-lumb; from the subcostal, furnishes, froi above downwards, the ilio-hyp< gastric and ilio-inguinal, and the it descends to join a branch from tl second. The second, third, and th; part of the fourth which enters ini the plexus break up into a sma anterior or ventral, and a large po: terior or dorsal division. The descending branch from the first joir a branch from the ventral division of the second to form th genito-femoral nerve, which arises next in order to the ilio-inguina The lateral cutaneous nerve of thigh arises by two roots from th dorsal divisions of the second and third. The femoral nerve arise by three roots from the dorsal divisions of the second, third, an fourth, the root from the third being the largest. The obturator nerv arises usually by three roots from the ventral divisions of the seconc third, and fourth, but the root from the second may be absent. Thj accessory obturator nerve, when present, arises by two roots from th


Fig. 488. —Diagram of the Right Lumbar Plexus.


ird and fourth, which are interposed between the roots of the femoral id main obturator nerves.

The branches of the lumbar plexus are accordingly as follows:

1. Muscular to psoas minor (when present), from first lumbar.

2. Muscular to quadratus lumborum, from first and second lumbar.

3. Muscular to psoas major, from second and third lumbar.

4. Two or three white rami communicantes, to the lumbar sympaetic gangliated trunk, from the upper two or three lumbar.

5. Ilio-hypogastric and ilio-inguinal, from first lumbar.

6. Genito-femoral, from first and ventral division of second lumbar.

7. Lateral cutaneous nerve of thigh, from dorsal divisions of second Ld third lumbar.

8. Femoral, from dorsal divisions of second, third, and fourth mbar.

9. Obturator, from ventral divisions of second, third, and fourth mbar.

10. Accessory obturator (when present), from third and fourth mbar, between the roots of the femoral and main obturator.

The ilio-hypogastric nerve, having pierced the outer border of the oas major near its upper part, passes outwards and downwards over e quadratus lumborum, lying below the subcostal nerve and behind e kidney. It then pierces the posterior part of the transversus >dominis a little above the iliac crest, and furnishes its lateral cutaneous anch, which, perforating the internal and external oblique, crosses e iliac crest at the junction of its middle and anterior thirds to be stributed to the integument of the adjacent part of the gluteal region, le nerve continues its course forwards between the internal oblique id transversus abdominis, supplying branches to these muscles and mmunicating with the ilio-inguinal nerve.' About 1 inch in front of e anterior .superior iliac spine it pierces the internal oblique, and then ns forwards between the fibres of that muscle which arise from the guinal ligament and the external oblique aponeurosis. Finally, it erces that aponeurosis 1 inch above the superficial inguinal ring, and distributed to the integument of the suprapubic region, where it is

series with the anterior cutaneous nerves. The ilio-hypogastric irve is serially continuous with the intercostal nerves; like these it ves off a lateral cutaneous branch, and then ends as an anterior itaneous nerve.

The ilio-inguinal nerve, having pierced the outer border of the psoas ajor lower down than, but close to, the ilio-hypogastric, passes diquely outwards and downwards over the quadratus lumborum, here it may lie below the lower end of the kidney or behind it. It en passes forwards immediately above the inner lip of the iliac crest meath the transversus abdominis. In this part of its course it may I st upon the iliac fascia and iliacus muscle. Near the anterior part the iliac crest it pierces the transversus, and here communicates with e anterior cutaneous branch of the ilio-hypogastric. It subsequently rforates the internal oblique, after which it descends through the lower two-thirds of the inguinal canal, and emerges through the sup ficial inguinal ring, where it lies lateral to the spermatic cord. Fina] having pierced the external spermatic fascia, it is distributed to ' integument of the inner side of the thigh in its upper third, and integument of the scrotum or labium majus, according to the s The ilio-inguinal nerve in its course supplies branches to the inter oblique and transversus abdominis muscles. It differs from the f hypogastric and intercostal nerves in the following two respects: it d< not give off any lateral cutaneous branch, and it is not distribui to the skin of the abdominal wall. The ilio-hypogastric and ilio-ingui nerves often arise by a common trunk, and their fibres for a considera part of their course are often contained in the same sheath.

The genito-femoral nerve (genito-crural nerve) passes forwa: through the psoas major, and appears on its superficial surface ab( the level of the body of the third lumbar vertebrae, where it lies close the inner border of the muscle. It sometimes pierces the muscle two parts, due to an early division of the nerve into its genital a femoral branches. It then descends upon the psoas sheath, passi slightly outwards, and crossing behind the ureter. At a variable c tance above the inguinal ligament (sometimes in the psoas major) 1 nerve divides into two branches, genital and femoral. The gem branch lies upon the external iliac artery close above the inguinal lij ment, and enters the inguinal canal through the deep inguinal n to be distributed to the cremaster muscle. The femoral branch descer on the outer side of the external iliac artery, and passes out behi the inguinal ligament, having just prior to this crossed the deep circu flex iliac artery. On entering the thigh it lies for about J inch wit] the femoral sheath, and subsequently, piercing the outer wall of tl sheath, is distributed to the skin over the femoral triangle.

The lateral cutaneous nerve of thigh pierces the outer border of 1 psoas major near its centre, and takes a direction downwards and 0 wards over the back part of the iliac crest into the iliac fossa. It tl crosses the iliacus under cover of the fascia iliaca towards the anter superior iliac spine, where it enters the thigh behind the outer end the inguinal ligament. For the distribution of the nerve in the thij see p. 564.

The femoral nerve (anterior crural nerve) pierces the outer bon of the psoas major about the level of the back part of the pelvic bri It then passes forwards, lying deeply between the psoas major a iliacus, and appears in the thigh behind the inguinal ligament. Whi in the abdominal cavity it gives branches to the iliacus muscle. I course and distribution of the nerve in the thigh will be found

P- 575 The obturator nerve pierces the inner border of the psoas maj at the back part of the pelvic brim, and lies upon the ala of the sacru having the lumbo-sacral trunk deep to it on its inner side. Passi deeply behind the common iliac artery it enters the pelvic cavity, ai passes along the outer wall a little below the pelvic brim, where it 1


ove the obturator artery. -It then enters the thigh through the turator canal. For the course and distribution of the nerve in the [gh, see p. 579.

The accessory obturator nerve (when present) pierces the inner border of the >as major close to the main obturator nerve, but, unlike it, does not enter the vie cavity. Its course is forwards along the inner border of the psoas major derneath the external iliac vessels, and it emerges on to the thigh by passing sr the superior pubic ramus beneath the pectineus muscle. Under cover of it muscle it divides into the following three branches: articular to the hipnt; muscular to the deep surface of the pectineus; and a reinforcing branch join the superficial or anterior division of the main obturator nerve. It is netimes very small and only represented by articular branches. At its origin s more closely associated with the femoral nerve than with the main obturator, is present in about 30 per cent, of cases.

Varieties of the Lumbar Plexus. —These assume the form of two types, high prefixed, and low or postfixed. In the prefixed type the anterior primary dsion of the third lumbar is a nervus furcalis, and takes part in the sacral

xus; whilst in the postfixed type the anterior primary division of the fifth nbar is a nervus furcalis, and takes part in the lumbar plexus.

Lumbo-sacral Trunk. —This is formed by the union of the ventral d dorsal divisions of the descending branch of the fourth lumbar

rve with the ventral and dorsal divisions of the anterior primary vision of the fifth lumbar. It is a large double trunk, which rests >on the ala of the sacrum, being at first under cover of the psoas ajor, and subsequently lying on its inner side, where it has the •turator nerve lateral and superficial to it. In its course it passes hind the common and internal iliac vessels, and in the pelvis, its two visions having joined those of the anterior primary division of the st sacral nerve, it takes part in the sacral plexus, entering more .rticularly the upper or outer band of that^plexus which is continued to the sciatic nerve.

The anterior primary division of the fourth lumbar nerve is known a nervus furcalis from the fact that it is distributed partly to the mbar and partly to the sacral plexus.

Lumbar Arteries. —These are branches of the abdominal aorta, mg parietal in their distribution, and serially continuous with the •sterior intercostal and subcostal arteries. They are eight in number, ur right and four left, and they arise in pairs, separately or conjointly, )m the posterior aspect of the parent trunk. They occupy the grooves the centres of the bodies of the first four lumbar vertebrae. As each tery winds round a vertebral body it passes beneath one of the fibrous ches of the psoas major and the lumbar sympathetic gangliated ^mk. It then passes behind the psoas major and lumbar plexus, and L reaching the interval between two adjacent lumbar transverse prosses it gives off a posterior branch. The upper two arteries pass neath the corresponding crus of the diaphragm, and those of the (ht side also pass beneath the cisterna chyli and the azygos vein.

1 four arteries on the right side pass beneath the inferior vena cava. le trunk of each lumbar artery gives off a few vertebra, branches to e body and ligaments of the adjacent vertebral and muscular branches


to the psoas major. The posterior branch passes backwards betv the adjacent transverse processes in company with the posh primary division of a spinal nerve, and divides into a medial and lat branch. The medial branch supplies the multifidus, and the lat branch supplies the sacro-spinalis, giving also cutaneous branches w. accompany the cutaneous nerves to the skin. Opposite an ir vertebral foramen the dorsal branch furnishes a spinal branch , wi enters the vertebral canal through the foramen, to be distributee the spinal cord and its coverings, as well as to the wall of the cana

The continuations of the arteries then usually pass behind quadratus lumborum, with the exception, as a rule, of that of the fou At the outer border of that muscle they pierce the aponeurosis of transversus abdominis, and pass forwards between that muscle and internal oblique as far as the lower part of the rectus abdominis, w] they enter. They furnish the following offsets: muscular to the qr ratus lumborum; extraperitoneal to the extraperitoneal arei tissue, which anastomoses with branches of the ilio-lumbar, thephre and the hepatic colic, and renal arteries, thus forming the ex peritoneal arterial plexus of Turner; muscular to the abdonr muscles, which anastomose above with the lower two intercostal ; subcostal arteries, below with the ascending branch of the deep circi flex iliac and ilio-lumbar, and in front with the inferior epigast Sometimes there are five lumbar arteries on each side, the fifth ] coming usually from the median sacral artery. Each of these pa: beneath the corresponding common iliac vessels, and having furnis' a lumbar branch, usually to the gluteus maximus, is distributed o the lateral mass of the sacrum, and ends in the iliacus, where it ar tomoses with the deep circumflex iliac artery.

The lumbar veins open into the inferior vena cava, those of left side passing behind the abdominal aorta. The vessels of e; side are connected by a series of longitudinal anastomosing veins front of the lumbar transverse processes, and the longitudinal ve: thus formed is called the ascending lumbar vein.

Subcostal Artery. —This vessel is the last parietal branch of thoracic aorta. It lies below the last rib, and is in series with posterior intercostals above and the lumbar arteries below. It wii round the side of the body of the twelfth thoracic vertebra, and coui along the lower border of the twelfth rib with the subcostal ner passing behind the lateral arcuate ligament of the diaphragm and front of the quadratus lumborum. This part of the vessel is beh: the kidney and the ascending or descending colon according to the si Its subsequent course corresponds with that of the lumbar arteries, anastomoses with the lower two intercostal arteries, the termi branches of the lumbar arteries, the ascending branch of the d< circumflex iliac, and the inferior epigastric artery. This vessel has be borne in mind in such operations as nephrotomy, nephrorrhap] and nephrectomy.

The subcostal vein of each side enters the thorax behind the late'


uate ligament of the diaphragm, the right opening into the azygos n, and the left into the inferior vena hemiazygos.

Subcostal Nerve. —This is the anterior primary division of the elfth thoracic nerve, and is in series with the eleventh or last internal. It accompanies the subcostal artery, and ultimately enters J sheath of the rectus abdominis, which muscle it pierces from behind wards to become an anterior cutaneous nerve. In its course it gives an undivided lateral cutaneous branchy which pierces the internal 1 external oblique muscles, and descends ir the iliac crest to be distributed to the n of the anterior part of the gluteal

ion; this branch may be small or absent, sides this branch it furnishes the follow; offsets: (x) dorso-lumbar to the anterior mary division of the first lumbar nerve;

I (2) branches to the quadratus lumborum, nsversus abdominis, internal oblique, and ramidalis.

Lumbar Glands. —These are very numer>, and are divided into four groups—

!-aortic, retro-aortic, and juxta-aortic, ht and left. They lie behind the parietal 'itoneum, in front of, behind, and along J sides of the aorta and inferior vena cava, e lower glands are continuous with the per members of the group of the common .c glands. The lumbar glands receive iir afferent vessels from the following irees: (1) the alimentary canal down to

anal orifice; (2) the liver and gall-bladder;' the pancreas; (4) the spleen; (5) the testes the male; the ovaries, uterine tubes, and per end of the uterus in the female; the kidneys; (7) the suprarenal glands; the vertebral part of the diaphragm; the common iliac glands; and (10) the iominal wall. Their efferent vessels unite form the lymphatic intestinal and the nphatic lumbar trunks, which in turn

n to form the cisterna chyli at the level of the body of the second nbar vertebra.

Common Iliac Arteries. —These vessels are the terminal branches of i abdominal aorta. They arise from that vessel opposite the centre the body of the fourth lumbar vertebra, a finger’s breadth to the t of the middle line, and they at once diverge from each other. Their irse is obliquely downwards and outwards over the lower portion the body of the fourth and the whole of that of the fifth lumbar -tebra, as well as the disc between the two. Each artery, on arriving

54


Fig. 488A.— Scheme illustrating the ‘ Groups ’ of Aortic Glands (modified FROM RoUVIERE).

Glands in front of aorta are pre-aortic, PA; those beside aorta are right and left lateral aortic, RL, LL ; the right lateral group is composed of sub-groups: A-V, between

• aorta and vena cava inferior ; PV, prevenous; RV, retro-venous ; and LV, latero-venous. Glands behind the aorta are not shown, being made up of derivatives from one or both lateral groups.


8 5 o


A MANUAL OF ANATOMY


opposite the lumbo-sacral articulation, ends by dividing into exter and internal iliac arteries. The length of the right common iliac about 2 inches, and that of the left about if inches. The left ve< is less oblique in direction than the right, and the course of each may indicated in the following manner: draw a line from a point £ ir below the umbilicus, a finger’s breadth to the left of the middle li to a point at the groin midway between the anterior superior iliac sp and the symphysis pubis, and let this line be slightly curved with 1 convexity directed outwards. About the upper 2 inches of this 1: indicate the course of the common iliac artery, and the remainder tl of the external iliac vessel.


Inferior Vena Cava


Aorta Suprarenal Lymphatics

Renal Lymphatics


Right Common Iliac Glands


Right External Iliac Glands


- Median Group of Lumbar Glands


Lymphatics ol Left Testis


-r- Sacral Glands


Right Internal Iliac Glands


Fig. 489.—Lymphatics of the Abdomen (after Mascagni).


Relations Anterior. The peritoneum, coils of the small intestin one halt of the aortic sympathetic plexus, and the ureter, which lath crosses the artery close to its termination, though it may be transferre o e commencement of the external iliac vessel. An additional supei hcial relation of the left common iliac artery is that it is crossed by tb superior rectal vessels.

Posterior.— Each artery rests upon the lower half of the body c

e +L OU ^- W ^°^ e that of the fifth lumbar vertebra, as we

as the disc above and below the latter, and the gangliated sympatheti trunk, the right vessel is separated from the foregoing structures b;

te commencement of the inferior vena cava, the terminal part of th lett common iliac vein, and the right common iliac vein, whilst the lei




























THE ABDOMEN


851


'essel is free from posterior venous relations. Lying deeply behind ach artery there are the obturator nerve, lumbo-sacral trunk, and >etween them the ilio-lumbar artery.

External. —On the outer side of the right vessel there are, from hove downwards, the inferior vena cava, right common iliac vein, nd psoas major. On the outer side of the left vessel is the psoas najor.

Internal. —On the inner side of the right vessel, from below upwards, there are the right common iliac vein, the left common iliac rein, and the hypogastric sympathetic plexus. On the inner side of he left vessel there are the left common iliac vein and the hypogastric )lexus.


Pelvic Colon Greater Omentum


1 ig . 490. — Transverse Section at the Level of the Disc between the Body of the Fifth Lumbar Vertebra and the Sacrum (after Symington).


_ It is to be noted that the left artery is related only to its own r ein, which lies on its inner side. The right artery, on the other [and, is related to three veins as follows: the inferior vena cava, which ies partly behind its upper end and partly on its outer side; the terminal >art of the left common iliac vein, which lies partly on its inner side nd partly behind it; and the right common iliac vein, which, from >elow upwards, lies first on its inner side, then behind it, and finally >n its outer side.

The inner, outer, and middle chains of common iliac glands lie on he inner, outer, and posterior aspects respectively of the common liac vessels.

Branches. —These are as follows: peritoneal to the peritoneum md extraperitoneal areolar tissue; muscular to the psoas major;















852


A MANUAL OF ANATOMY


ureteric to the ureter (all of small size and unimportant); exter iliac; and internal iliac. In some cases the common iliac gives one or other of the folJpwing vessels: ilio-lumbar, median sacral, late sacral, lumbar, or an aberrant renal artery.

Varieties. —The chief variety affects the length of the vessel. It may very short, which is due either to a low bifurcation of the aorta or a high bifui tion of the artery itself; or it may be very long, which is due to exactly oppo causes. When abnormally long, the vessel is usually more or less tortuous.

Collateral Circulation. —After ligature of a common iliac artery, the cl channels by which the circulation is carried on are as follows: (1) the supe: epigastric of the internal mammary from the first part of the subclavian ana: moses with the inferior epigastric of the external iliac; (2) the lumbar branc of the aorta anastomose with (a) the ascending branch of the deep circumj iliac from the external iliac, and ( b) the ilio-lumbar of the internal iliac; (3) superior rectal of the inferior mesenteric from the aorta anastomoses with (a) middle rectal of the internal iliac, and (b) the inferior rectal of the inter pudendal from the internal iliac; (4) the median sacral from the aorta anastomc with the lateral sacral branches of the internal iliac; and (5) the pubic branc' of the obturator from the internal iliac and of the inferior epigastric from external iliac, both of one side, anastomose across the middle line with the coi sponding branches of the opposite side. The vesical and middle and inferior rec arteries of one side anastomose in a similar manner with those of the oppo: side.

Common Iliac Veins. —Each vein is formed by the union of t external and internal iliac veins opposite the corresponding sac] iliac articulation on a level with the brim of the pelvis. They un to form the inferior vena cava opposite the upper border of the bo of the fifth lumbar vertebra a little to the right of the middle lb behind and on the right side of the right common iliac artery. T right vein is necessarily shorter than the left, and it ascends almc vertically, lying at first medial to, then behind, and finally on t outer side of its own artery. The left vein ascends very oblique from left to right, lying medial to its own artery, and then behind tb of th right side. It crosses the median sacral artery, and is cross by the superior rectal vessels and the left half of the aortic plexi The common iliac veins are usually destitute of valves.

Tributaries. —These are chiefly the external iliac, internal ilia and ilio-lumbar. In addition, the left vein receives the median sacr vein.

Ihe left common iliac vein is mainly the persistent and enlarged transve1 branch (transverse iliac) which connects the right and left supracardinal periganglionic veins of the embryo above the back part of the pelvic brim. I commencement, however, is developed from the left veins. The right comrn< iliac vein is developed from the part of the right cardinal vein which interven between the termination of the right external iliac vein and the right extremi of the transverse iliac vein.

Common Iliac Lymphatic Glands. —These glands are about m

in number, and are arranged in three groups —lateral, intermediate, ai medial—which lie along the common iliac artery. The afferent vesse of the lateral and intermediate groups are derived from the external ai internal iliac glands; the afferent vessels of the medial group procee



THE ABDOMEN


853

1 the other hand, directly from the viscera, from (1) the prostate and, (2) the base of the bladder, (3) the lower part of the vagina, and ) the cervix uteri.

The efferent vessels of all the common iliac glands of one side pass the juxta-aortic glands of the same side.

External Iliac Artery.—This vessel is the larger of the two terminal visions of the common iliac in the adult. It extends from the lumbocral articulation to the lower margin of the inguinal ligament, where is continued into the femoral artery. Its course is along the pelvic im, and at the groin it passes through the vascular lacuna at a point idway between the anterior superior iliac spine and the symphysis

Pelvic Colon Bladder

l /


G - 49i- —Transverse Section at the Level of the Second Sacral Vertebra

(after Symington).


ibis. The course of the vessel may be indicated in the following anner: draw a line from a point f inch below the umbilicus; a finger’s 'eadth to the left of the middle line, to a point at the groin midway 'tween the anterior superior iliac spine and the symphysis pubis, and t this line be slightly curved with the convexity directed outwards, bout the upper 2 inches of this line indicate the course of the common ac artery, and the remainder that of the external iliac vessel. The le indicating the course of the vessel corresponds to the lower part of tat which has been given as indicating the course of the common iliac, be vessel is from 3J to 4 inches long, and its direction is downwards, itwards, and forwards.
















§54


A MANUAL OF ANATOMY


Relations —A nterior .—The artery is covered by the parietal p toneum aild extraperitoneal areolar tissue, the portion of the la which is related to it being known as Abernethy’s fascia. The ri vessel at its commencement is crossed by the terminal part of ileum, and sometimes by the vermiform appendix, whilst the left its commencement is crossed by the pelvic colon, and each may crossed by the ureter. In the female both arteries are crossed superic by the ovarian vessels. Near the inguinal ligament each vesse crossed by the deep circumflex iliac vein, and the genital branch of genito-femoral nerve lies upon it. The testicular vessels in the rr also lie for a short distance upon it in this situation, and the vas defer for ligamentum teres of the uterus) arches over it from without inwai The external iliac glands lie along the artery. Posterior .—The art rests upon the iliac fascia at the pelvic brim, except for a little ab the inguinal ligament, where it lies upon the psoas muscle with intervention of the fascia which forms its sheath. The right art at its commencement has its own vein behind it for a short distance, c each vessel may have the accessory obturator nerve as a deep poste] relation. Lateral .—The psoas major covered by the iliac fascia, genito-femoral nerve, and its femoral branch. Internal .—The p< toneum, the extraperitoneal areolar tissue (Abernethy’s fascia), wh binds the artery with its vein to the iliac fascia, the external iliac v (except for a short distance above on the right side, where the veir behind the artery), and the vas deferens near the inguinal ligamen

Branches.—These are as follows: muscular to the psoas maj glandular to the external iliac glands (both unimportant); infer epigastric; and deep circumflex iliac. For the latter two, see pp. ' and 732.

Varieties of the Branches. —(1) The origin of the inferior epigastric maytransferred to the femoral, or to the arteria profunda femoris, and the dc circumflex iliac may be transferred to the femoral. (2) The medial circumfl obturator, or arteria profunda femoris may arise from the external iliac, in wh latter case two large arteries would emerge on to the thigh beneath the ingui ligament.

The external iliac vein is the continuation of the femoral vein, extends from the lower border of the inguinal ligament to the sac iliac articulation on a level with the brim of the pelvis, where it jo: the internal iliac, and so forms the common iliac vein. The right v< lies at first medial to its artery, and then behind it. The left vein 1 medial to its artery throughout. Its chief tributaries are the infer epigastric and deep circumflex iliac veins.

The external iliac vein of adult life is preceded in function by the infer] gluteal vein of the embryo, which is the primitive vein of the lower limb. In i process of development the upper part of the femoral and the whole of 1 external iliac vein of the adult are continued upwards from the long saphenc vein to the cardinal portion of each common iliac vein, and the inferior glut* vein is now a tributary of the internal iliac.

Collateral Circulation. —When the external iliac artery is ligatured, tj collateral circulation is carried on through the following channels: (1) t


t


i.


THE ABDOMEN


855

iperior epigastric of the internal mammary from the first part of the subclavian nastomoses with the inferior epigastric of the external iliac; (2) the pubic ranch of the obturator from the internal iliac anastomoses with the pubic ranch of the inferior epigastric; (3) the ilio-lumbar and superior gluteal, both om the internal iliac, and the abdominal branches of the lumbar arteries from le aorta anastomose with the deep circumflex iliac of the external iliac; (4) the Dturator from the internal iliac anastomoses with the medial circumflex of the •teria profunda femoris; (5) the inferior gluteal from the internal iliac anas>moses with the medial and lateral circumflex, and the first perforating of the •teria profunda femoris; (6) the gluteal anastomoses with the external circum3X and the ascending branch of the medial circumflex from the arteria pronda femoris; (7) the companion artery of sciatic nerve of the inferior gluteal lastomoses with the perforating branches of the arteria profunda femoris; and ) the superficial perineal and dorsal artery of penis of the internal pudendal from ie internal iliac anastomose with the superficial and deep external pudendal of le femoral.

External Iliac Lymphatic Glands.—These glands are related to the eternal iliac vessels, and are about twelve in number. They are usually rranged in three chains —lateral, intermediate, and medial—there eing about four glands in each chain. The lateral chain lies on the der side of the external iliac artery, between it and the psoas major tuscle, except the lowest gland, which lies upon that muscle. The iter mediate chain lies in front of the interval between the external iac artery and vein. The medial chain lies below the level of the exjrnal iliac vein, upon the upper part of the lateral wall of the pelvis, bove the obturator nerve. One of the glands of this chain may lie ithin the pelvic entrance to the- obturator canal, and is spoken of 5 the obturator gland, but it is not constant. The lowest gland of ich chain lies close to the deep aspect of the inguinal ligament, and lese are known as the retro-femoral glands—* lateral, intermediate, and ledial respectively.

The afferent vessels of the external iliac glands convey lymph from tie following sources:

1. The deep inguinal glands.

2. Some of the superficial inguinal glands.

3. The deep structures of the antero-lateral abdominal wall below tie umbilicus.

4* To a certain extent the glans penis or glans clitoridis, these unphatics passing along the inguinal canal.

5. The adductor muscles.

6. The prostate gland and prostatic urethra in part.

7- The bladder.

8. Part of the membranous and the bulbar portions of the urethra.

9- The upper part of the vagina.

10. The body and cervix of the uterus.

The efferent vessels of all the external iliac glands pass to the ommon iliac glands.

Lacunar Region.—The lacunar region is situated between the Jguinal ligament and the anterior margin of the hip bone, and is ivided into two compartments—muscular and vascular.



8 5 6


A MANUAL OF ANATOMY


The muscular lacuna is subdivided into two portions, lateral iliac, and medial or pectineal, by the ilio-pectineal septum , wl separates the psoas magnus from the pectineus. This septum pa; between the ilio-pubic eminence and the fascia iliaca at its poini junction with the upper part of the pubic portion of the fascia 1; The lateral compartment, which is of large size, is bounded in front the outer part of the inguinal ligament and the iliac fascia, behind the anterior margin of the ilium, and medially by the ilio-pectir septum. It transmits (i) the ilio-psoas muscle, (2) the lateral cutane nerve of thigh, and (3) the femoral nerve. The medial compartmen situated between the superior pubic ramus behind and the upper p of the pubic lamina of the fascia lata in front, the ilio-pectineal sept being lateral tout. It contains the origin of the pectineus muscle, £ is shut off from the abdominal cavity by the attachment of the pn lamina of the fascia lata to the medial portion of the pectineal line, connection with this portion of the fascia lata there is a bundle fibres, known as the pectineal ligament [of Cooper ). This ligam extends between the ilio-pubic eminence and the pubic tubercle, tween which points it is attached to the medial portion of the pectir line in front of the pectineal part of inguinal ligament, being clos incorporated with the pubic lamina of the fascia lata.

The vascular lacuna is situated anterior to the other two. Il bounded posteriorly by the connection between the iliac fascia £ the pubic lamina of the fascia lata, whilst anteriorly it is bounded the central portion of the inguinal ligament and the downward p longation of the fascia transversalis to form the anterior wall of femoral sheath, that fascia being here strengthened by the deep feme arch. It gives passage to (1) the external iliac vessels, the vein be medial to the artery; and (2) the femoral branch of the genito-femo nerve, which lies close to the outer side of the artery. The part of t lacuna medial to the external iliac vein forms the femoral ring, wh is closed by the femoral septum.


STRUCTURE AND DEVELOPMENT OF THE ABDOMINAL

VISCERA.

Structure of the Stomach.

The wall of the stomach is composed of four coats—serous, mi cular, submucous, and mucous.

The serous coat is formed by the peritoneum, which covers eve part of the organ except (1) along the lesser and greater curvatur and (2) the uncovered trigone, situated on the posterior surface, bel( and a little to the left of the cardiac orifice.

The muscular coat (muscularsi externa) is composed of plain muscui tissue disposed in three layers—external or longitudinal, middle circular, and internal or oblique. The external or longitudinal fib) are continuous with the longitudinal fibres of the oesophagus, and


THE ABDOMEN


CEsophagus


857

pyloric end of the stomach they are continuous with the longitudinal

es of the duodenum. They are most abundant along the lesser vature, and partially separate off in that region a tubular portion the cavity known as the intergastric canal, which is thought provide for the rapid trans;sion of fluids. The middle or ular fibres completely surround stomach from the fundus to pyloric end. At first they are 1 and irregular in position, Longitudniaijiuscuiar-j

over the pyloric canal they thick. At the pylorus they ome augmented, and are gathi together into a thick muscular l, called the pyloric sphincter, ich lies within a circular fold the mucous membrane. The ermost fibres of this ring bele continuous with the circular es of the duodenum. Some of circular fibres appear to be itinuous with the superficial 'ular fibres of the right side of the lower end of the oesophagus.

3 internal or oblique fibres are continuous with the circular fibres of

the left side of the lower end of the oesophagus. They loop over the stomach immediately to the left of the cardiac orifice, and run very obliquely downwards and to the right for a considerable distance on both surfaces of the organ. They cannot be traced as far as the pylorus, but end by inclining downwards to the greater curvature, where they blend with the circular fibres.

The submucous coat situated between the


Pyloric Sphincter

Fig. 492. — Dissection showing the Muscular Layers of the Stomach.


Cardiac Orifice


CEsophagus


Fundus


sser Curvature

mmon tic Duct


Stic Duct


Pylorus


■ile Duct '


--Greater

Curvature


-Pancreatic Duct


Duodenum

493.—The Stomach and Duodenum opened.


is


muscular and mucous coats. It is composed of areolar tissue, and serves partly as a connecting medium, and % as a bed in which the arteries subdivide before entering the cous coat.









8 5 8


A MANUAL OF ANATOMY


The mucous coat is covered by a single layer of columnar epithe It is soft and pulpy, and in the empty state of the viscus is th into folds, which are for the most part longitudinal, and are due t loose connection between the muscular and mucous coats. T however, are readily effaced when the stomach becomes distei It is thickest towards the pyloric end, and in healthy adults it ] light crimson colour, while in early life this is heightened into a b rosy tint. After death, however, it presents a mottled appear being marked with grey-brown patches. When examined with a it presents a great number of polygonal depressions, varying in diar from T Jo to -lo inch, the largest being near the pylorus. These in

to it a honeycomb appear


Duct


Mucosa with Cardiac Glands


Muscularis Mucosae


Submucosa


) Muscular Coat


The mucous membrane surrc ing them is elevated into r by subjacent capillary netw and in the region of the py these ridges present proc( called plicce villosce. The gonal depressions are beset minute pores, which are the hces of the gastric glands. 1 glands, which belong to the tui variety, are placed perpen larly in the mucous coat, are closely packed together upright stakes. They are of kinds, cardiac and pyloric, tween which there are ce differences.

The cardiac glands are siti the cardiac two-thirds.


in


Peritoneal Coat


duct of each forms about oneof the entire length of the g It is lined with a single lay


Fig. 494.—The Cardiac Glands of

'A, 1 , A. L AO AAAA^VJ. VV i- LAA CL OAAA£;A^ ACL

the Stomach (highly magnified). columnar epithelium. The

end of the duct is connected with two or three gland-tubes, 1 represent two-thirds of the entire gland. Each gland-tube is dfv into a neck, body, and fundus. The neck is the part connected the duct, and it forms one-third of the length of the gland-tub( is narrower than the body, and is lined with coarsely granular polyt cells, which almost completely fill it, thus leaving a very small li These are called the central or chief cells. Between these am basement membrane there are interposed large oval or sph granular cells, each having a clear nucleus. These, which are < the parietal or oxyntic (‘ acid-forming ’) cells, do not form a contii layer, but are placed at intervals, and they give rise to small swe on the wall of the neck. The body is wider than the neck, and i two-thirds of the length of the gland-tube. It is lined by a prolong











































THE ABDOMEN


Mucosa with Pyloric Glands


Muscularis Mucosae


859

he central or chief cells of the neck, which almost completely fill it, which have now become somewhat columnar and transparent, ween these cells and the basement membrane there are a few ietal or oxyntic cells here and

e. The parietal cells of the k and body impart the characstic beaded appearance to the id-tube. The fundus is the d deep end of the gland-tube.

The pyloric glands are situated he pyloric third. The duct of 1 forms one-half of the entire (th of the gland. It is lined 1 a single layer of columnar helium. The deep end of the t is connected with two or re gland-tubes, which represent -half of the entire gland. The k of each tube is comparatively rt, and the body is branched ts deep extremity. The neck body are lined with cubical mlar cells, representing the tral or chief cells of the cardiac ids, and they are not so vded as in the cardiac glands,

Tat there is a very distinct en. There is an entire absence of parietal or oxyntic cells, and body of each gland-tube has an undulating, convoluted outline.

pyloric glands are serially continuous with Brunner’s glands of small intestine.




} Submucosa


K Muscular Coat


Peritoneal Coat


Fig. 495.— The Pyloric Glands of the Stomach (highly magnified).


Summary of the Cardiac and Pyloric Glands.


Cardiac Glands.

)ucts short.

hand-tubes long.

hand-tubes almost filled with coarsely granular polyhedral cells, called central or chief cells.

arnien very small.

dand-tubes have parietal or oxyntic cells between the central cells and the basement membrane.


Pyloric Glands.

1. Ducts long.

2. Gland-tubes short.

3. Gland-tubes lined with cubical

granular cells.

4. Lumen distinct.

5. Gland-tubes destitute of parietal

or oxyntic cells.


At the deepest part of the mucous coat, and forming a part of ii re is a stratum of plain muscular tissue, called the muscularis mucos> 'scularis interna), which is disposed in two layers—outer longitudim ^ inner circular. The mucous membrane is also provided wit l phoid tissue in the interspaces between the deep ends of the gastri





















86 o


A MANUAL OF ANATOMY


glands. In the cardiac part of the stomach this lymphoid tissue oci in the form of isolated collections, called lymph follicles, which be; resemblance to the solitary glands of the intestinal mucous membr; In the neighbourhood of the pylorus these lymph follicles bec< aggregated, and so resemble somewhat the aggregated lymph nodules of the small intestine.

Blood-supply—Arteries.—Along the lesser curvature there

(1) the left gastric branch of the coeliac artery in two divisions,

(2) the right gastric branch of the hepatic, also in two divisions. A 1 the greater curvature there are (1) the right gastro-epiploic of gastro-duodenal of the hepatic from the coeliac artery, and (2) the gastro-epiploic of the splenic from the coeliac artery. At the fur there are the short gastrics of the splenic artery.

The branches arising from all these arteries enter the muscular < without piercing the peritoneum. They subsequently make t way inwards to the submucous coat, where they break up into bram which freely anastomose with one another. Fine branches then e] the mucous coat, which run upwards between the closely-packed gas glands, round which they form by their anastomoses a delicate capil] network with its meshes elongated in the direction of the gland-tu From their network somewhat larger vessels proceed upwards, wl by their anastomoses form a coarser and more superficial netw around the orifices of the ducts of the glands. The arteries along lesser curvature are smaller, longer, and not so tortuous as those al the greater curvature; further, they do not anastomose so fre features which are probably attributable to the fact that the le curvature, unlike the greater curvature, undergoes relatively li change in distension of the stomach.

Veins.—These arise from the superficial network of capilla round the orifices of the ducts of the glands. They take a downw course between the gland-tubes, and on reaching their deep ends t form a plexus. From this plexus branches proceed outwards to submucous coat, in which they form another plexus. The branc arising from this latter plexus, having passed through the musci coat, terminate in the following veins: (1) the right gastro-epipl which opens into the superior mesenteric; (2) the left gastro-epiploic ■ short gastrics, which open into the splenic; (3) the left gastric; < (4) the prepyloric, the latter two opening directly into the portal v The veins of the stomach contain numerous valves, which are si ciently competent in early life to oppose the return of venous blc but in the adult they are incompetent.

Lymphatics.—These commence near the free surface of the muc membrane either in loups or in enlargements, and they take a do ward course between the gland-tubes, where they open into a 1 work of lacunar spaces. The branches which proceed from ' network, on reaching the deep ends of the glands, form a ple> and the vessels issuing from this plexus, on entering the submuc coat, form another plexus, the lymphatics of which are furnished v



86i


THE ABDOMEN


yes. The vessels which emerge from this latter plexus accompany bloodvessels, and pass to the lesser and greater curvatures, and vicinity of the hilum of the spleen. At the lesser curvature y are connected with the coronary glands, at the greater curvature i the subpyloric glands,

1 st those which accomy the short gastric

ries pass through the nic glands, the efferent >els of all these glands mately passing to the iac glands. In addition the lymphatic vessels described there is a peritoneal lymphatic

[US.

Nerves.—These are ded from (i) the two i nerves, and (2) symletic plexuses from the

ac plexus. The right us nerve descends upon Fig - 49 5 A -— Scheme (after Rouviere) of the .posterior surface of the Chains of Lymph Glands accompanying the nach, whilst the left r Ranches of the Celiac Artery (CA)

ve descends upon the V * £ T. 1 •? 7 l"

rinr wvfnr? cT/rrr Also shows the lymphatic territories of the stomach

v jace. ine sym- corresponding with the vascular supplies. ietic plexuses closely

)mpany the arteries. The nerves form two gangliated plexuses posed of non-medullated nerve-fibres. One of these is situated veen the longitudinal and circular fibres of the external muscular and corresponds to the plexus myentericus of Auerbach of the stine. The other plexus is situated in the submucous coat, and esponds to the plexus of Meissner of the intestine.


■ he explanation of the right vagus nerve descending upon the posterior tee, and the left upon the anterior surface, of the stomach is found in the

ion assumed by the stomach in the early embryo. Briefly stated, at that )d of life the stomach is a straight tube, and its surfaces are right and left, two vagi nerves, therefore, right and left, naturally descend on the right left surfaces of the viscus. When, however, the stomach turns over on its owing to the enlargement of the omental bursa towards the left, the surface h was originally right becomes posterior, and the surface which was originally becomes anterior. Thus the right nerve eventually descends on the posterior mally the right) surface, and the left nerve descends on the anterior (originally eft) surface.

Pylorus.—The opening between the pyloric end of the stomach the duodenum is provided with a sphincter muscle, called the nc sphincter. This is formed by an aggregation of the circular cular fibres, which causes the mucous membrane to project in form of an annular fold, thus giving rise to the pyloric valve. The



862


A MANUAL OF ANATOMY


pyloric sphincter is only relaxed when the contents of the sto are being passed into the duodenum. At all other times it is condition of firm contraction, and the pyloric orifice then take form of a cleft.

The average length of the stomach is about io inches, and its average at the widest part about 5 inches. Its capacity is very variable.

Development of the Stomach (for general relations, etc., of the early stc see p. 79).—The cavity of the stomach begins to show a dilatation befoi 5 mm. stage. The dilatation increases fairly rapidly, possibly in assoc with the freedom ensured by the fact that the organ is carried on the wall of the lesser sac; the area of the fundus is quite distinct before the e the first month as an enlargement to the left of the line of the wall of the 1 which is only connected with the body and pyloric portion. The fundus not begin to grow out to its proper size, however, before the end of the s month.


Fig. 496.—Three Sections in Region of Stomach at Differeni

Developmental Stages.

The first shows the condition of the wall at 10 mm. The second show nature of the pits in the lining layer during the third month. The section illustrates the sudden changes seen in the disposition of the 1 membrane, etc., in passing from the pyloric region (P) to the duodenuir


The lining layer of the stomach is fairly thick, and is embedded in a mesodermal coat. In the fifth week (Fig. 496) a faint indication of the civ muscular coat can be seen on the right side of the viscus (left in figure) lining epithelium shows several tiers of cells where cut obliquely, but prob as in the lower part of the section, there are really some three or four layers the middle of the second month the circular coat is more or less complete, some indications of the other coats are to be found. The lining layer, beco thinner as the stomach grows, shows irregularities on its free surface, espec in the pyloric portion. The organ is now very vascular. During the 1 month the surface irregularities of the epithelium, now a single cell layer, definite short pits (Fig. 496), which are not—at any rate at first—mad folding of the layer as a whole, but by inequalities in height of its cells mesoderm grows in later between the pits. This pitting of the epithe appears to be more marked in the pyloric region. The pit-like appearan

due to section; they are really of the nature of cleft-like sinkings in the sin layer.

In the fifth month and subsequently glands are formed as secondary growths of the floors of these pits, starting apparently from certain eosino




THE ABDOMEN


863

>, which constitute altogether or in part the floors. These eosinopile cells [i to be the direct precursors of the parietal cells of the cardiac glands, rhe cavity of the stomach presents certain folds or grooves which appear >e fairly constant. Among these are two grooves which run longitudinally ig the lines, more or less, of the two curvatures, and two folds project into cavity on either side of the future lesser curvature. These folds enclose the - of the ‘ internal gastric canal/ which is thus almost as well marked in the >ryo of the second month as in many adult bodies. These folds and grooves lot pass into the pyloric part.

rhe pyloric portion of the stomach is, in the embryo, a contracted, tube-like il, much longer compared with the rest of the organ than in the adult. It )t, however, to be looked on as part of the duodenum, from which it may be mguished very early (Fig. 496).


Structure of the Intestinal Canal.

Small Intestine. The wall of the small intestine, which is cylin al, is composed of four coats—serous, muscular, submucous, and

ous. The serous coat is formed by peritoneum derived from the mesenT P ro per. In the case of the duodenum it is incomplete, but it ns a complete investment to the jejunum and ileum, except along irrow interval corresponding to the mesenteric border of the bowel, re the peritoneal investment becomes continuous with the two

rs of the mesentery proper. rhe muscular coat (muscularis externa) is composed of plain musr tissue, disposed in two layers, external or longitudinal, .land rnal or circular.. The external or longitudinal fibres are continuous 1 the corresponding fibres of the stomach, and they are best marked tg the anti-mesenteric border. The internal or circular fibres are tmuous with the outermost fibres of the sphincter pylori, and form uch thicker layer than the longitudinal. The muscular coat attains greatest thickness in the duodenum, whence it gradually diminishes, ween the two muscular layers there is a gangliated plexus of nonaillated nerve-fibres, called the myenteric plexus (Auerbach’s plexus), also a plexus of lymphatic vessels.

Hie submucous coat is situated between the muscular and mucous s. It is composed of loose areolar tissue, and serves partly as a lectmg medium and partly as a bed in which the arteries subtle. It contains a gangliated plexus of non-medullated nerve^s, called the plexus of the submucosa (Meissner’s plexus), and a “Us of lymphatic vessels. In the duodenum this coat lodges the denal glands, and the deep ends of the solitary nodules project it throughout. ^ J

rhe mucous coat is red and thick in the upper part of the small stme, but pale and thin in the lower part. It is covered by a e layer of columnar epithelium. The protoplasm of the cells is Itudmally fibrillated. Underneath the epithelium there is a baseb ^ m .k rane > known as the subefiithelial endothelium , and underf s * s main part of the mucous coat, which is essentially corn'd of adenoid tissue—that is to say, retiform tissue containing in


864 A MANUAL OF ANATOMY

its meshes lymph corpuscles. At the deepest part of the mucous and forming a part of it, there is a stratum of plain muscular ti called the muscularis mucosce (muscularis interna ), which in i situations is disposed in two layers—outer longitudinal and circular. In some places, however, only the outer longitudinal is present. The mucous coat is beset all over with minute projecl called villi, and is sometimes called the villous coat. These impart to it a woolly appearance like the nap of velvet. It dimm in thickness from above downwards, and is characterized by the folic structures: (i) circular folds, (2) villi, (3) duodenal glands, (4) intes glands, (5) lymphoid nodules, and (6) aggregated lymphoid nodule Of the foregoing structures the circular folds, villi, and aggre^ nodules constitute the macroscopical (naked-eye) characters ol mucous membrane, the others forming its microscopical character The circular folds (valvulae conniventes) are permanent folds 0 mucous membrane which cannot be effaced. They are absent

the first part of the duodenum for a disl of from 1 to 2 inches from the pylorus. ( mencing about the upper end of the second of the duodenum as small straggling folds, become large and distinct at the place oj trance of the bile-duct and pancreatic (about 4 inches from the pylorus). Throug the rest of the duodenum and in the upper of the jejunum they are still prominent, am placed close to each other. In the lower of the jejunum they become smaller, and placed farther apart. In the upper part oi ileum they become still smaller and more gular, and they finally disappear just be] the centre of the ileum. They are cresc( folds placed across the bowel, and each con of two layers of mucous membrane applied 1 to back, with a little submucous areolar ti Fig. 497. —The Circu- intervening. Their average length is a lar Folds. 2J inches, and the average breadth of eac

about J inch. The majority of them ex round the bowel for from one-half to two-thirds of its circumfere Some, however, describe complete circles, whilst a few are arrai in a spiral manner so as to describe from one to three turns round tube. Some of them begin and terminate in bifurcated extremi whilst others present abrupt single extremities. The purpose sei by the circular folds is a twofold one. In the first place they incr the extent of the absorbing and secreting surface of the mucous m brane, and in the second place they delay the passage of the intest contents, and so afford time for digestion and absorption.

In connection with the circular folds of the duodenum the com] orifice of the bile-duct and pancreatic duct has to be noted. At



1
















THE ABDOMEN


865


ction of the inner and posterior aspects of the second part of the )denum, where the upper two-thirds and lower third of that part st, there is a small eminence of the mucous membrane, called the

idenal papilla. It lies at the


er end of a vertically-placed 1 , which bifurcates so as to form ind of hood for it. From the er part of the papilla a fold ends downwards for some disce, which acts as a bridle, and es the apex a downward direc1. On the summit of this papilla re is an opening which reprets the common orifice of the > ducts. These ducts, having versed the wall of the second t of the duodenum obliquely f inch, unite to form one duct, ch, before piercing the mucous t, presents an enlargement


Fig. 498.— Duodenal Papilla. A, papilla; B, circular folds.


Goblet Cell


ed the ampulla, but subsequently narrows at its final ending. In ampulla a gallstone may become lodged and delayed in its down'd progress toward the duodenum. About 1 inch above the duodenal papilla there is another small papilla upon which there is another minute opening. This represents the orifice of the accessory pancreatic duel.

The villi commence at the beginning of the duodenum on the outer side of the pylorus, and extend as far as the margins of the segments of the ileo-colic valve. They are minute projections of the mucous membrane, to which they impart a velvety appearance, and may be visible to the naked eye, but are more readify seen with the aid of an ordinary lens if a portion of bowel is floated in water. They are closely set upon the mucous


Fig. 499.—Two Villi.

villus, Showing striated basilar are C K l0SeI y Set "P 0 * the mucous )r der, columnar epithelium, goblet membrane (circular folds included),


hmp -- epithelium, goblet v ils, and lacteal vessel; B, villus, except over the solitary glands, mowing the capillary bloodvessels. Their total number is said to be

about four millions (Krause). The are conical, cylindrical, leaf-like or finger-like processes, varying ^ngth from To to To inch. They are larger and more numerous e lower part of the duodenum and in the jejunum, especially at

55












866 A MANUAL OF ANATOMY

its upper part, than in the ileum, and they diminish both in size number from above downwards, becoming somewhat filiform in ileum. Each villus is an elevation of the mucous membrane coverec a single layer of columnar epithelium. It is composed of (i) adei tissue, (2) a capillary network of bloodvessels, (3) one or more lac vessels ensheathed by plain muscular tissue, and (4) arborization nerve-fibrils derived from the plexus of the submucosa.

Between the columnar epithelial cells of the free surface there amoeboid lymph corpuscles. Beneath the epithelium is a basen membrane composed of flattened cells, and known as the subepith endothelium. The cells of this basement membrane send procc between the columnar cells of the free surface, and also are conne< with the branched cells of the retiform tissue of the adenoid tis One artery (sometimes two) enters the base of the villus and asc( to near the centre. Here it breaks up into a number of branc which form a copious capillary network. From this plexus the bi is returned by one or two venous radicles, which leave the villu its base, where they open into the venous plexus of the mucous m brane. In the centre of the villus there is a lacteal vessel, which c mences near the tip in a blind bulbous extremity, or if there shoul<


two lacteals, they originate in the fom a loop. The wall of the lacteal vess( formed by a single layer of endothelial pk which are connected by processes with branched cells of the retiform tissue of adenoid tissue. The vessel is ensheathec longitudinal plain muscular fibres der; from the muscularis mucosae, their fi cells being connected with the basen membrane of the villus. The villus is vaded by adenoid tissue—that is to retiform tissue with its meshes filled a amoeboid lymph corpuscles. The branc cells of this retiform tissue are connectec processes, on the one hand, with the er thelial plates which compose the wall of lacteal vessel, and on the other hand ^ the cells of the basement membrane near surface, and these latter in turn send processes between the columnar epith cells of the free surface.

The villi play a most important par absorption, partly through their cop capillary networks, and partly through t lacteals. The lacteals serve specially for absorption of fats, which is probably effected in the following man the columnar epithelial cells at the free surface take up the sapon) and emulsified fats, which they transfer to the amoeboid lymph )


Duodenal Glands


Fig. 500.—Section of the Duodenum, showing Duodenal Glands (highly magnified).




































THE ABDOMEN


867

iscles between them. These corpuscles then carry the fats inwards rough the adenoid tissue into the lacteal vessel.

Duodenal glands (Brunner’s glands) are confined to the duodenum, id are serially continuous with the pyloric glands of the stomach, ley are very numerous in the commencement of the duodenum, iere they form a continuous layer of gland tissue extending as low the entrance of the bile-duct and pancreatic duct. Beyond this ant they gradually diminish in number, and ultimately disappear ar the duodeno-jejunal flexure. They belong to the class of race3 se or acmo-tubular glands,, and they differ from the pyloric glands the stomach in having their tubules more branched and in having


Villus ____


Intestinal Gland


Solitary Nodule Muscularis Mucosas


Submucosa


Circular Muscular Fibres


>ngitudinal Muscular Fibres

Peritoneal Coat __=§§§=


’Mucosa


Fig. 501. —Vertical Transverse Section of the Small Intestine

(highly magnified).


iger ducts. Otherwise the structure of the two kinds of glands is nlar. The duodenal glands lie embedded in the submucous coat, i their long ducts pass through the whole thickness of the mucous d, upon the surface of which they open between the intestinal glands, tte of them, however, open into these glands. The glands can easily displayed by removing the peritoneal and muscular coats of the ^denum and a little of the submucous areolar tissue, when they ^ear as small, round, grey-coloured masses like millet seeds, varying diameter from T V to inch.

the intestinal glands (crypts of Lieberkiihn) are found in large fibers over the whole of the mucous membrane of the small intestine, well as that of the large bowel. They belong to the class of simple



































868


A MANUAL OF ANATOMY


tubular glands, and are to be regarded as small diverticula of tl mucous membrane. Each gland takes the form of a simple tub which is closed and slightly enlarged at its deep extremity, and opei by its other end on the surface between the villi. The glands a] present on the circular folds as well as in the intervening parts. The are placed vertically and close together, and are confined entirely to tf mucous coat, in which they extend from the free surface to the musci laris mucosae. In length they vary from ^ to yTq inch. Each glan is composed of a basement membrane lined with columnar epitheliun and the lumen is of large size.

The solitary nodules are present over the whole extent of the mucoi membrane of the small intestine. They assume the form of small, whit round, or oval nodules, which project by their deep ends into the sul mucous coat, whilst their superficial ends give rise to slight elevatior of the free surface, where they have the openings of the intestin; glands placed around them. They are found upon, as well as betweei the circular folds. In structure each solitary nodule is composed ( adenoid tissue containing large numbers of lymph corpuscles, and pe: meated by capillary networks. Each nodule is surrounded at its dee part by a copious plexus of lymphatic vessels, or by lymphatic sinuse The solitary nodules are simply lymphoid tissue.

The aggregated nodules (Peyer’s patches) are peculiar to the sma intestine, and average about thirty in number in the adult, bein

more numerous in early life. They are situate along the free or anti-mesenteric border of th bowel, which must therefore be opened alon its attached or mesenteric border in order t preserve them. They are largest, best market and most plentiful in the lower half of the ileun In the upper part of the ileum and lower pai of the jejunum they become smaller and mor scarce, and they disappear as a rule above th centre of the jejunum. They vary in lengt from inch to 4 inches, their breadth rangin from J inch to 1 inch. They are for the mos part oblong, their long axis coinciding with tha of the bowel. In the upper part of the ileui and lower part of the jejunum, however, the are somewhat circular. Each aggregated nodul is composed of a group of solitary lymphoi nodules, surrounded by lymphatic plexuses c lymphatic sinuses. The area of each aggregate nodule is slightly elevated, and there are no vil over the lymphoid nodules, whilst the opening of the intestinal glands are arranged in


Fig. 502.—An Aggregated Lymphoid Nodule.


circular manner round each nodule. There are no circular folds ove the aggregated nodules. The aggregated nodules are best marke in young persons. Towards middle life they fade away, and in ol









THE ABDOMEN 869

persons they are usually only distinguishable as discoloured portions of the mucous membrane.

Blood-supply—Arteries.—The duodenum receives its arteries from the superior pancreatico-duodenal of the gastro-duodenal from the hepatic, and the inferior pancreatico-duodenal of the superior mesenteric. The jejunum receives its arteries from the jejunal branches of the superior mesenteric. The ileum receives its arteries from the ileal arteries, and its terminal part in addition receives its arterial supply from the ileal branch of the ileo-colic from the superior mesenteric.

Veins.—The destination of the venous blood of the small intestine is the superior mesenteric vein, and thereafter the portal vein. The veins are provided with valves which are competent in early life, but in the adult they are incompetent, and therefore allow regurgitation of blood to take place towards the small intestine, as happens in cases of portal obstruction.

Lymphatics.—These form a copious plexus of valved vessels, which is situated in the submucous coat. This plexus receives the lymphatics of the mucous membrane and the lacteals of the villi, and it surrounds the deep ends of the solitary nodules. Its efferent vessels pierce the muscular coat, and in doing so they take up the lymph from an intramuscular plexus of lymphatics, which lies between the longitudinal and circular layers. They then leave the bowel at the mesenteric border, where they pass between the two layers of the mesentery, and on their way to the cisterna chyli they traverse the superior mesenteric glands.

Nerves.—These are derived from the superior mesenteric sympathetic plexus, and they form two gangliated plexuses of nonmedullated nerve-fibres. One of these is situated in the muscular coat between the longitudinal and circular layers, and is known as the myenteric plexus (Auerbach’s plexus) (plexus of the muscular coat of the intestine). The other is situated in the submucous coat, and is called the plexus of the submucosa (Meissner’s plexus). The branches of this latter plexus are distributed to the muscularis mucosae and the mucous membrane with its villi.

Characters of Different Parts of the Small Intestine—Duodenum — Peritoneum. —There is no mesentery and only a partial investment of peritoneum. Muscular coat. —This is very thick. Submucous Coat.- —-This contains the tubular portions of the duodenal glands. Mucous Coat .—The characters of this coat are as follows: (1) circular folds, except in the first 1 or 2 inches, (2) villi, (3) intestinal glands, (4) solitary nodules, (5) ducts of the duodenal glands, (6) common orifice of the bile-duct and pancreatic duct, and (7) orifice of the accessory pancreatic duct.

The diameter of the duodenum is from 1^ to 2 inches.

Jejunum — Peritoneum. —There is a mesentery, and the bowel is surrounded by peritoneum except along its mesenteric border. Muscular Coat .—This is comparatively thin. Mucous Coat .—This has the following characters: (1) circular folds, (2) villi in abundance, (3) intestinal glands, (4) solitary nodules, and (5) aggregated lymphoid nodules in its lower half.

The diameter of the jejunum is about i-| inches.

Ileum — Peritoneum. —In this respect the ileum resembles the jejunum.


870


A MANUAL OF ANATOMY


Muscular Coat. —This is very thin. Mucous Coat. —The characters of this co, are as follows: (1) circular folds in upper half, but small and sparse, there beii none in the lower half; (2) villi, but in fewer numbers; (3) intestinal gland (4) solitary nodules; and (5) aggregated lymphoid nodules.

The diameter of the ileum is about 1^ inches.

Development of Small Intestine. —The epithelial lining is at first like th

of the stomach, and the muscular coat develops also in a similar way. Vacuol appear in the epithelium, leading in the duodenum to subdivision of the lume but not in the rest of the gut, where, however, they may produce pouches. Vi appear in the upper part first, about the seventh week, and are found throughoi the gut in the fourth month. They may form by the breaking up of longitudin ridges, or may form separately. Glands develop as simple pits between villi the fourth month, first in the upper gut. They tend to branch later. T, duodenal glands seem to be formed from the simple forms by lateral branchii and growth in length during the fourth month. They are not fully formed ; birth, however.

Large Intestine.—The wall of the large intestine, which is sacculate* is composed of four coats—serous, muscular, submucous, and mucou

The serous coat forms a complete investment to the vermifori appendix, caecum, transverse colon, and pelvic colon. As regarc the ascending colon and descending colon, it is incomplete, being absei behind.

The muscular coat (muscularis externa) is composed of plain muscuk tissue disposed in two layers—external or longitudinal, and internal ( circular.

The longitudinal muscular fibres are for the most part collected ini three flat bands, called taeniae coli, except upon the rectum. In tl intervals between these bands there are some longitudinal fibres, but the are very few and scattered. The taeniae, which are about J inch i breadth, commence upon the caecum at the base of the vermiform a] pendix, and they extend along the several parts of the large intestir as far as the rectum, where they spread out and form a continuot covering, which completely surrounds that part of the bowel. Upc the caecum, ascending colon, descending colon, and iliac colon the teni from their disposition are called anterior, postero-internal, and poster* external. Upon the transverse colon they are so placed as to be calle anterior or omental (greater omentum), postero-inferior or free, an superior or meso-colic (transverse meso-colon). They are shorter tha the bowel to which they are applied, with the result that the tube drawn together or puckered, and thus thrown into sacculi. Thei being three taeniae, there are three rows of sacculi between them, an inasmuch as the taeniae are placed at nearly equal distances from eac other, the sacculi are pretty much of equal dimensions. Between th successive sacculi there are constrictions, usually containing fat. Th sacculi give rise internally to large pouches, and the constrictior between the sacculi produce internally sharp crescentic rugae, whic separate the pouches from each other. When the taeniae are divide*: the sacculi and constrictions entirely disappear, and the large bow* becomes elongated into a smooth cylindrical tube. Along the cours of the taeniae there are a number of small processes of peritoneum cor


THE ABDOMEN


871


ining fat, called appendices epiploicae. They are best marked on the ansverse colon and on the upper part of the pelvic colon, and are least arked, as a rule, on the caecum. Except in the case of the transverse )lon, these are chiefly found along the postero-internal taenia, but in le case of the transverse colon they are principally met with along the Dstero-inferior taenia.

The circular fibres are thin and scattered over the sacculi, but in le constrictions between them they become aggregated. Upon the ctum and anal canal they form a thick layer, which in the latter tuation is known as the sphincter ani internus.

The submucous coat is in all respects similar to that of the small Ltestine.

The mucous coat is pale and greyish in colour, except in the rectum, here it is red. Its epithelium is similar to that of the small intestine.

is destitute of circular folds and villi, and consequently presents a nooth surface. It contains large numbers of intestinal glands, which iound in mucus-secreting goblet cells. It also contains solitary anphoid nodules, which are especially prevalent in the vermiform ppendix and caecum. The deepest part of the mucous coat is formed y the musculans mucosce ( muscularis interna).

Blood-supply—Arteries.—These are as follows: (1) appendicular, >r the vermiform appendix; (2) anterior and posterior caecal, for the mim; (3) colic of ileo-colic and right colic, for the ascending colon; |.) middle colic, for the transverse colon (all branches of the superior lesenteric); (5) left colic, for the descending colon; and (6) sigmoid rteries, for the iliac colon and pelvic colon (the latter two being branches f the inferior mesenteric).

Veins.—The destination of the venous blood of the vermiform ppendix, caecum, ascending colon, and transverse colon is the superior lesenteric vein, whilst the blood of the descending colon, iliac colon, nd pelvic colon is carried into the inferior mesenteric vein. In both ases the further destination of the blood is the vena portae. As in the mall intestine, the veins have valves which are competent in early life, ut not so in the adult.

The lymphatics will be found described on pp. 799 and 802.

Nerves.—These are derived from the superior mesenteric sympathetic plexus and the inferior mesenteric plexus, which latter is an ffshoot from the aortic plexus. The disposition of the nerves correponds with that in the small intestine.

The large intestine diminishes gradually in size from its commencement to its termination. Its diameter varies in different parts, the xtremes being 2\ inches and 1 inch.

Characters of the Large Intestine — Peritoneal Coat. —This presents at frequent ntervals small projections called appendices epiploicae. Muscular Coat. —The ongitudinal fibres are for the most part arranged in three taeniae. Mucous "oat. —This is destitute of ( a ) circular folds, (b) villi, (c) duodenal glands, and d ) aggregated nodules, but it is provided with (1) intestinal glands, and (2) solitary lodules. Outline of Tube. —The bowel presents three rows of sacculi, except in -he vermiform appendix and rectum.


872


A MANUAL OF ANATOMY


Development. —There is nothing remarkable about the epithelial grow which resembles that of the small gut. The lumen is at first very small and walls thick. The bowel begins to enlarge about the time of its entrance ii the belly, but even then is much smaller than the small intestine. Villi deve' in it during the fourth month, but become smaller and less distinct during succeeding months. Glands form between the villi, but the details of their forr tion are not known with certainty. Villi are found in the vermiform appea in the fourth month, with gland formation.


Structure of the Vermiform Appendix.—The vermiform appenc is entirely covered by peritoneum, which forms a more or less compk


Solitary Nodules


Fig. 503.—Transverse Section of the Vermiform Appendix

(magnified).

meso-appendix or appendicular mesentery. It has a muscular coa composed of an external longitudinal and internal circular layer, both < which completely surround it. The submucous coat contains in gre; abundance solitary nodules of large size, and the mucous coat contaii a few solitary nodules, as well as a few intestinal glands. The base < the appendix is situated at a point on an average rather more tha 1 inch below the ileo-colic valve, according to Treves. The openir by which the appendix communicates with the caecum is occasional guarded by a fold of mucous membrane, which is known as the ileo-coll valve (valve of Gerlach).






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873

The vermiform appendix is usually regarded as the remains of the herbivorous aecum. It is also looked upon as an appendage of the lymphoid system, and as ich it would belong to the class of structures represented by aggregated nodules -namely, lymphoid organs.

Ileo-colic Valve (Valve of Tulpius).—This valve is situated at the oint where the terminal part of the ileum opens into the junction etween the caecum and ascending colon. The orifice, as seen from the iterior of the large intestine, has the form of a slightly oblique cleft bout J inch long, and running in an antero-posterior direction. It is ounded above and below by the two segments which form the valve, nd which project into the large intestine. The upper or ileo-colic egment is prominent, and occupies an almost horizontal plane. The


Dwer or ileo-ccecal segment, longer than the upper, is concave superiorly, nd occupies an oblique plane. The anterior part of the cleft is rounded h, whilst the posterior part tapers to a point. The segments meet in ront of and behind the cleft, and form two prominent folds, which are >rolonged round the wall of the bowel for some distance. These folds re known as the frenula. Each segment is composed of two layers »f mucous membrane, one of which belongs to the ileum, and the other 0 the caecum or colon, as the case may be. These two layers are coninuous with each other at the free margin of the segment, and they ontain between them submucous areolar tissue and circular muscular Tres, both of which are derived partly from the ileum and partly from he large intestine. The longitudinal muscular fibres and the serous or >eritoneal coat take no part in the formation of the segments, being








874


A MANUAL OF ANATOMY


continued uninterruptedly from the ileum to the large intestine. ' mucous membrane which covers the opposed surfaces of the segrm belongs to the ileum, and is therefore provided with villi. The muc membrane of the other surfaces—that is to say, the surfaces which I away from each other (downwards and upwards respectively)—be! to the caecum and colon, and are destitute of villi. The villi thus < appear at the margins of the segments. The valve may be descril as being formed by an inversion of the terminal part of the ileum i the large intestine. That part of the ileum, having passed upwa and to the right with a slight inclination backwards, enters the la intestine. As it does so it leaves behind its serous and longitudi muscular coats, and takes with it its circular muscular, submucc and mucous coats, the corresponding coats of the large intest accompanying it in the inversion. The ileo-colic valve prevents regurgitation of the contents of the caecum into the ileum. It generally believed that the mode of action of the valve is as folio 1 when the caecum becomes distended the frenula of the valve are stretcl and exercise traction upon its segments, which are thereby brou| together. The valve is usually represented in figures as it appears wl the caecum has been inflated and dried. In the fresh condition segments of the valve are thick and tumid, and the appearance is ] unlike that of the pyloric valve as seen from the duodenum or of cervix uteri as seen from the vagina; the frenula, again, are much 1 apparent in such a caecum.

For the structure of the rectum, see p. 960.

Development of Positions of the Stomach and Intestinal Canal.

This subject is dealt with shortly on pp. 61-65 and 79-81. These pa should be studied before reading what follows.

Dorsally, the roof of the mid-gut is at first close to the notochord, but, growth goes on, it comes away from this close relationship, drawing out mesoderm between them as it does so, to form the dorsal mesentery, the man in which this change is effected is not quite clear.

At an early stage, therefore, the alimentary tube in the abdomen can described as being short, median in position, extending from the septum tra versum to the cloaca, and, between these limits, making a short curve, com ventrally, and suspended by a median dorsal mesentery. The vitelline duct attached to it at the lowest part of its curve, and as development proceeds 1 intestinal loop lengthens, so that this lowest part of it passes out of the abdon into the ‘ umbilical sac.’ The elongation of the loop implies a correspond! lengthening of the dorsal mesentery opposite it (see Fig. 44).

Stomach. —This is a dilatation of that part of the tube which is resting the septum transversum. Its attachment here lengthens and thins as the li 1 grows in the septum, and at the same time its dorsal mesentery (meso-gastriu is pouched out to the left, carrying the stomach with it, and turning it so tl its left surface becomes somewhat ventral. The pouch of dorsal meso-gastrii is known as the omental bursa.

Intestinal Canal. —This canal is at first very short and almost straight, aij gs has been stated, it communicates freely with the yolk-sac. At this sh there is no indication of a division into small and large intestine. When wide opening leading to the yolk-sac becomes constricted and converted i: the vitelline duct, the intestinal canal undergoes lengthening, and a conspicu'


THE ABDOMEN


8 75


) is formed, which projects into the cavity of the proximal part of the umbilical i, this cavity being a direct prolongation of the coelom or body-cavity. This ) is spoken of as the U-loop. The convexity of the bend of the loop is directed ! ralwards, and the vitelline duct is connected with the convexity. The loop two limbs, which lie at first parallel to each other. One limb is cephalic, >er, or proximal, and leads from the duodenal loop of the gut; the other limb audal, lower, or distal, and leads to the caudal end of the gut. Upon the al limb a bud makes its appearance. This assumes the form of a blind diverlum, or cul-de-sac, which is the rudiment of the ceecum. The appearance of caecal evagination is the first indication of the division of the intestinal canal > small and large intestine. The primitive small intestine is the part on the



Fig. 5 ° 5 - —The U-Loop, 8 mm., just projecting into the Umbilical Sac. Left and right views. Vitelline duct cut Short.


)ximal side of the rudimentary cascum, and the primitive large intestine is the ft extending from the rudimentary caecum to the caudal end of the gut.

The portion of mesentery which is drawn out as the proper mesentery of the loop contains the superior mesenteric artery between its layers. The artery originally continued on beyond the loop as the vitelline artery, but this soon appears and leaves its trunk as the superior mesenteric.

As the stomach lies in the front wall of the rudimentary lesser sac (bursa lentalis), its pyloric end is directed towards the right, and the very short piece the tube which comes next, the future duodenum, lies rather to the right of the ddle line, and is attached to the median common dorsal mesentery by a thick so-duodenum, which projects on that side of it, just below the opening of the ser sac.







8y6


A MANUAL OF ANATOMY


The intestinal tract is thus seen to consist of intra- and extra-abdorr portions, part of the colon being in the abdomen, and the anterior limb of loop being connected with the duodenum by an intra-abdominal duod umbilical loop of gut.

These different parts of the intestinal tract can be seen in Fig. 505, in w the conditions in a 8 mm. embryo simplified are shown from both sides; the lobe of the liver has been cut away to expose the mesentery and gut, for it cc down at this stage on the left side of the bursa omentalis and mesentery a: as the right lobe on the other side. The neck of the umbilical loop of gut p< out between the two lobes of the liver in a deep notch in the ventral edge oJ


Fig. 506.—Left-sided Views of Umbilical Loop at 9 mm. (Above) and 10 1

(Lower Figure).

organ. An angled bend is seen where the hind-gut is continuous with the hin limb of the loop; this is produced by the attachment here to the gut of a retent band in the mesentery, extending from the peri-aortic region in the neighbourhc of the cceliac artery. The angle must not be mistaken for the left colic flexu with which it has nothing to do; it is gradually effaced as development procee and its ultimate position, if it persisted, would be some little distance to 1 left of the mid-point of the transverse colon.

With the exception of the short length of the duodeno-umbilical piece, wh becomes the first coil of the jejunum, the small intestine is formed in the umbili sac, as are those parts of the large gut which become the ascending and right k of the transverse colon. Formed in this sac, the gut enters the abdomen a




THE ABDOMEN


877


ain stage, and within this cavity is finally disposed in its proper situations.

processes that lead to the ‘ rotation ’ of the intestine can thus be divided descriptive purposes into three stages—the development outside the belly, entrance into the abdomen and the immediate mechanical results of this nge, and the subsequent assumption of the definitive positions.


Fig. 507.—Two Diagrams to show Earlier Stages of Gut and Mesentery within the Belly and in the Umbilical Sac.


First Stage. —The general disposition in the earlier part of this stage can be a in Fig. 507, A and B. It is marked by the fairly rapid growth in length of anterior or proximal limb of the umbilical loop, forming coils. The ruditttary lesser sac enlarges, passing down on the left side of the median abdominal sentery, between it and the liver. Two or three points in connection with the


1. 508.—Schemes of the Umbilical Loop showing the Sort of Growthchanges THAT OCCUR WITHIN IT (SEE TEXT).

ngating proximal limb must be noted, as they are concerned with the subseent entry and disposal of the gut within the belly cavity: in the first place, ' proximal limb lies, from an early stage on the right side * of the loop, as can


The immediate cause of this is not certain. It may be due to the position the stomach, making the duodenum pass towards the right, or it may be iociated with the development of the vitello-umbilical anastomosis, which 3 in the concavity of this part of the limb of the loop, but any definite state"nt on the subject would be unwarranted.







A MANUAL OF ANATOMY


878

be seen in the figures; secondly, the growth of the proximal limb is associated w marked increase in the depth of the corresponding mesentery of the loop, that the distance between the coils of this limb and the superior mesente artery is much increased; the hinder limb of the loop does not grow like 1 proximal limb, and its distance from the artery remains unchanged, whence comes about that the artery gets relatively nearer and nearer to the hinder lii of the loop. At the back of the loop, where it is passing through the open: in the abdominal wall, the artery is still approximately midway between the t limbs, and it is only distal to this that the unequal growth of the constituent pa of the mesentery of the loop leads to the one-sided position of the vessel.

Fig. 509 illustrates the appearance at the end of the first stage. The cseci is now a large dilatation with a conical extremity, placed on the left side of • mass of coils of small intestine. The mesentery of the small gut is long, and 1 superior mesenteric artery is close to the colon and caecum. The bursa omenh really extends caudally along the whole extent of the left side of the int abdominal colon and meso-colon, separating these from the left lobe of the liv in the figure, however, it is shown as somewhat pushed up, to allow the med: colon and meso-colon to be seen. At the end of this stage, then, the intesti: coils are on the right of the caecum and colon in the umbilical sac, the super mesenteric artery is close to the colon and far from the coils, and the bu omentalis is on the left of a ‘ median abdominal septum ’ made of abdominal coi and meso-colon.

Second Stage. —The recession of the umbilical gut within the belly is brou^ about by a fall in ‘ intra-abdominal tension ' resulting from lessened growth-r of the liver. This organ fills all the available space in the abdomen during 1 second month, growing pari passu with the surrounding parts, but in the ea part of the third month its rate of growth falls behind that of these parts. T does not at first affect the mass in the umbilical sac, and is met by increase in 1 amount of blood in the liver vessels, which are consequently dilated. In 1 tenth week, however, approaching the 40 mm. stage, this dilatation of lr vessels may be considered to have reached its maximum, and any further incre; in the capacity of the abdomen calls for the appearance of some additional si stance to fill the space which otherwise must come into being. The umbili coils are alone able to fulfil this role, and the extra-abdominal or amniotic pressi not being lessened by the fall in the growth-rate of the liver, the contents of 1 umbilical sac are pushed by it into the abdomen to compensate for the inter: fall. It is to be noted now that as the coils enter the abdomen the liver can retr; before them by the discharge of blood from its over-dilated vessels. Thus 1 distension of the liver not only leads to the beginning of the intestinal mo ment, but, by its disappearance and the tendency of the organ to return to undistended condition, leads to the completion of the recession and the provis: of space for the entering coils when and where it is needed, without any pressi on these coils.

The movement having started, all the evidence points to it being rapi( completed. Owing to the size of the caecum, possibly also owing to the gr< size of the dilated venous spaces found round it at this stage, and to the srr size and thick wall of the colon, the ccecum is retained in the sac to the last, a the proximal limb passes first into the abdomen. It does this, not en masse, 1 in continuity, slipping into the belly with its mesentery, the elongation of wh allows it to enter the abdomen, although the superior mesenteric vessels a the colic part of the distal limb are still in the sac. But the proximal limb already been seen to be on the right-hand side of the distal limb, so that it ent the abdomen below the right lobe of the liver, which retreats before it—that the coils of intestine enter the belly on the right-hand side of the median colic ‘ septu (Fig. 509) already mentioned. This ‘ septum ' of abdominal colon and mecolon is thus pushed over to the left by the coils, as seen in Fig. 510, and 1 back against the left dorsal wall of the abdomen, the coils lying on its vent (originally right) surface. Crossing in this way to the left, the coils necessak pass below the colic part of the distal limb of the loop and the mesenteric artery, wb*




THE ABDOMEN


879


509


■The Condition within the Gut enters the Abdomen:


Umbilical Sac shortly before the Left and Right Views.







88 o


A MANUAL OF ANATOMY


is, as already seen, associated with this limb. Moreover, in going to the le and in pushing the median septum to this side, the coils have passed on tl dorsal side of the lower part of the omental bursa, which now hangs down ov them; this is the first form of the greater omentum of the definitive state, althou^ there is as yet no adhesion between the overhanging layers and the colon, ( between it and the dorsal wall.

The ccecum is the last structure to enter the abdomen, and, on entering, it li (Fig. 512) on the mass of coils of small intestine. It forms an angle, howeve with the rest of the colon when it lies in this situation, and as the colon is thic' walled, there is a tendency for the bent piece to straighten itself and come in line with the rest; this, and doubtless also the rapid increase in size of the coils the small gut, which now begins, cause the caecum to assume a right dors


Fig. 510.—Diagram of Section through Root of the Loop, showing ho its Cranial Limb, being below and on the Right of the Other, mu:

PASS BELOW THE CAUDAL LlMB AND THE MAIN VESSELS AND PUSH TP

Intra-abdominal Meso-colon to the Left.

Overhanging omental bursa is represented as rolled up.

position with reference to the mass of coils, on the right side of the neck of tl mass, and thus to come into its proper plane. This is found to occur a few da; after the entrance of the gut into the belly, and with its occurrence the secor stage comes to an end.

Third Stage. —It can be understood from a consideration of the figures that tl caecum and end of the colon, when they move to the right, must pass over ti line of the superior mesenteric artery, for the mesentery of the small intestn is attached along the line of the artery on its lower aspect. Thus the cole will come to lie across the duodenum, and the caecum below and to the rig! of this, and the artery will cross the duodenum lower down. This complet the twist of the mesentery of the loop, which finishes the second stage, ar leaves the peritoneal layers now in a position which can be understood from tl scheme in Fig. 463.



THE ABDOMEN


881


The intestines are now essentially in their proper ‘planes/ and the third t e comprises only the developments and extensions in these positions that l to the conditions found m the adult. The descending meso-colon, laid


. 511.— Scheme to show Result >f Entry of Proximal Limb to rHE Right of Median Septum,

VHICH IT PUSHES TO THE LEFT >lND Dorsally against the Dorsal Wall: Cecum remains n the Sac.


Fig. 512.—Conditions immediately

AFTER THE ENTRANCE IS ACCOMPLISHED.

The caecum and mesenteric vessels lie on the mass of coils, the vessels to the right.


k against the left dorsal wall, as seen in Fig. 463, is, at the beginning of this

e, relatively short, so that the left colon only reaches the inner edge of the it aspect of the left kidney; as growth proceeds, this meso-colon lengthens,


5 r 3 -—Actual Conditions in Embryo just after Cecum has entered the Belly at the End of Second Stage.


1 the colon thus comes to lie farther out, finally reaching its definitive position, 1 the meso-colon becomes adherent to the dorsal wall. This dorsal adhesion presses from within outwards, and when the colon has reached its final posi 56



882


A MANUAL OF ANATOMY


tion, extends to the line of the gut, and thus fixes the bowel in situ. Or right side the colon, about the end of the third month, becomes attached v it crosses the duodenum, and at its caecal end. Between these two fixed the colon and meso-colon are free at first, but attachment of the meson just to the right of the superior mesenteric vessels is soon found. The l between the fixed parts slowly lengthens as the liver gets relatively sm and as it lengthens it becomes curved out with a convexity upwards and t right, ultimately forming in this way the hepatic flexure with the ascei and right portion of the tranvserse colon. The formation of these parts slow process, not really completed at birth. It is accompanied by an extei of the area of meso-colic adhesion, this, however, falling short of the lii advancing colon, so that this is free to lengthen farther. Thus the mesopart of the original loop mesentery becomes attached to the dorsal wall, the


Fig. 514.— Schemes to show Position of Meso-colon and Colon at Var

Stages, indicated by the Measurements.

a, b, left and right mesocolons; t, position at birth.

remaining free as the mesentery of descriptive anatomy; the line of attack of the mesentery is therefore in reality the limit of adhesion of the right meso-cc Between the upper end of the fixed meso-colon on the left and the att ment to the duodenum on the right the free colon and meso-colon are apj to the dorsal aspct of the lower part of the rudimentary lesser sac, invagina this somewhat. The colon stands away from the dorsal wall here, and it is dorsal surface of the meso-colon, the surface continuous with the adhe surfaces of the right and left meso-colons, that is applied (see Fig. 463) to wall of lesser sac. The adhesion of these applied parts to each other, extendir far as the position of the pancreas in the wall of lesser sac, brings into existence transverse meso-colon and the incidental attachment of the greater omentum tc transverse colon', by extension of the adherent area the bursal wall above pancreatic line becomes fixed to the dorsal wall, and constitutes the posU wall of the small sac.

Caecum and Vermiform Appendix. —The caecum appears about the week of embryonic life as a bud in connection with the distal limb of the U








THE ABDOMEN


883


intestine. It assumes the form of a blind diverticulum, which is at first of liform dimensions. It soon, however, becomes conical. The proximal part idergoes enlargement, and represents the permanent caecum. The distal part mains long and narrow, and represents the vermiform appendix, which ultimately jcomes connected with the left and posterior part of the caecum. The various )sitions occupied by the caecum and its migration to the right iliac fossa have st been referred to. Suffice it to say that it lies at first on the left side of the edian line, then it crosses to the right side, being at this stage below the liver, id finally is left in position as the liver retracts.


Peritoneal Structures.

1. Meso-gastrium. —It has been pointed out that the part of the dorsal minion mesentery which carries the stomach becomes pouched out to the left ; ie resulting sac is frequently termed the meso-gastrium, but more appropriately le rudimentary lesser sac (bursa omentalis). Its opening, to the right, is just x>ve the thick part of the mesentery known as the meso-duodenum, and is datively small. The sac is the result of rapid increase of a right-sided depression

the mesentery, the pneumato-enteric recess ; a left-sided recess shows itself sry early, but disappears almost at once. The opening corresponds in the iult with the line of the pancreatico-gastric folds. The portion of the lesser sac etween these and the opening into lesser sac is added later as an additional

cess to the right of the mesenteric line, associated with the growth of the iferior vena cava.

The rudimentary lesser sac is at first ‘ free ’ towards the left. After the return E the bowel, which (see Fig. 511) has caused the colon to invaginate its lower rail, the dorsal wall of the sac becomes attached to the abdominal wall, while the olon becomes fixed to its lower aspect. Thus the left half of the transverse leso-colon comes into existence, attached dorsally, while the pancreas, which ad extended in the back layers of the sac, now becomes fixed dorsally, the tyers behind it disappearing. The spleen forms in the outer part of the sac all, which, as the result of the fixation just described, has now a dorsal attachlent towards the left.

The outer part of the sac wall, thus left still ' free,’ is therefore the structure

rmed the ‘ meso-gastrium’ in the adult; the spleen, placed in this, is held by to the dorsal wall on the one hand (lieno-renal fold) and, on the other, to the

omach (gastro-splenic ligament). The greater omentum is evidently made by the bulging of the front and lower art of the rudimentary sac over the colon, to which it acquires a secondary ttachment. The lesser omentum (ventral mesentery) is drawn out from the upturn transversum.

2. The meso-duodenum is a thickening of the median mesentery just below the pening into the lesser sac. The duodenum is attached on its right front, and 1 at first a very short segment of the tube. The two pancreatic outgrowths ccur into the meso-duodenum, the upper one being immediately below the pening into lesser sac and opposite the attachment of its lower and back wall, ito which it extends. The lower growth, forming the head of the gland, enlarges 1 the meso-duodenum, with corresponding lengthening of the duodenum, which Iso begins to assume a curved form round the growing head. The whole curve f the duodenum is ultimately formed in this way as a result of the growth of the ead of the pancreas. It is clear, then, that this curve has nothing to do with tie rotation of the gut returning to the abdomen, but it is possible that the xtreme end of the duodenum may belong to the commencement of the proximal nib of the loop, secondarily fixed in position.

3 - Caecum. —The caecum, being originally a bud or outgrowth of the gut, has o mesentery, and is originally entirely surrounded by peritoneum.

4 - Vermiform Appendix. —The vermiform appendix, being originally the find narrowed end of the caecum, or, in other words, a diverticulum of the ‘Scum, is also destitute of a mesentery, properly so called, and is invested by


884


A MANUAL OF ANATOMY


an extension of the peritoneal envelope of the caecum. There is, however, most cases a fold of peritoneum pertaining to the vermiform appendix, whi extends along it for about one-half or two-thirds of its length. This fold called the meso-appendix or appendicular mesentery, and it is derived from t left or inferior layer of the mesentery proper, close to the ileo-colic junctic Its presence is due to the drawing out of vessels as the appendix is formed.


Structure of the Liver.


The liver has two coats, external and internal. The external serous coat is formed by the peritoneum, and is incomplete (see p. 77* Within the serous coat is the fibrous or areolar coat, which is kno\ as the fibrous capsule of the organ. It is for the most part thin, exce where the peritoneal coat is deficient. It is continuous all over t surface with the scanty amount of areolar tissue which pervades t interior of the organ and connects the hepatic lobules. At the por hepatis it surrounds the common hepatic duct, hepatic artery, ai vena portae, under the name of the capsule ofiGlisson. The subdivisio of this capsule accompany the various branches of the duct, arter and vein as these ramify throughout the liver in the portal cana'

The liver substance is composed of a gre number of small polyhedral masses, call hepatic lobules, which are closely pack< together, and at the centre of each of whi< is an intralobular or central vein. In m< there is very little areolar tissue between t] lobules, which are therefore for the most pa confluent. In some animals, however, notab the pig and camel, there is a very distin amount of areolar tissue between the lobule which therefore stand clearly apart from ea( other.

The average diameter of a hepatic lobule aV inch. One of its surfaces is called the has It is by this surface that the lobule is set upc the wall of a sublobular vein, and the intr lobular or central vein, having emerged fro: the lobule through the centre of its bas


Fig. 515.—Section of the Liver, showing a Large Hepatic Vein and its Tributaries (after Kiernan).


opens at once into the sublobular vein. The lobules, therefore, rel tively to the sublobular veins, on which they are ranged, are sessil When a sublobular vein is opened and viewed from within, an appearara something like mosaic work presents itself, the closely-set bases of tt lobules being visible through the thin wall of the vein, and the minut opening of the intralobular or central veins appearing in the centre ( each base. Each lobule is composed of hepatic cells, permeated b capillary networks of bloodvessels and bile-capillaries.

Bloodvessels. —The liver derives its blood from two sources—namely the portal vein and the hepatic artery. These two vessels, togethe with the hepatic duct, are invested by the capsule of Glisson at th























THE ABDOMEN


885

>rtal iissure. Iheir several branches, ensheathed by prolongations of lisson's capsule, ramify from this point throughout the liver, being intained in the system of canals known as portal canals. Each of these nals contains (1) a branch of the portal vein, (2) a branch of the jpatic artery accompanied by a plexus of nerves, (3) lymphatic vessels, id (4) a minute duct, all these being loosely surrounded by a prolonuaDn of Glisson’s capsule.

The portal vein ramifies within the liver like an artery. In the irtal canals its branches receive as tributaries small capsular and ginal veins , and they go on ramifying until they arrive at the interbular areas. Here they anastomose freely with one another around e lobules, and so form the interlobular plexuses . The branches which ise from these plexuses enter the lobules on all sides except their tses, and form in the interior of each lobule an intralobular plexus. -om this plexus a few radicles converge towards the centre of the bule, where they form by their lion the intralobular or central vein. le portal blood, though dark in lour, is very rich, being derived Dm, amongst other sources, the Dmach and small intestine.

The hepatic artery is a branch of n e coeliac artery. As its branches iverse the portal canals they give f capsular branches to the fibrous psule of the liver, and vaginal inches, which supply the walls of e vessels in the portal canals, as ill as their Glissonian sheaths. The anches of the artery finally end minute interlobular arteries , which pply the walls of the interlobular

ins and bile-ducts. According to Fig. 516.—Two Hepatic Lobules me authorities they send minute (highly magnified).

pillary branches into the interior lobule showing the intralobular each lobule to join the mtra- plexus; B, lobule showing the

Dular plexus of the portal vein, but hepatic cells,

is view is not held by others.

The function of the hepatic artery and its branches is to nourish e tissues of the liver, whilst the portal blood supplies the materials fich are elaborated by the hepatic cells.

( The hepatic veins commence in the centre of each lobule as an ralobular or central vein. The intralobular veins open into the blobular veins, which are closely adherent to the bases of the lobules.

sublobular veins join to form larger sublobular veins, and these turn terminate in the hepatic veins, which are not in direct contact th the lobules. The hepatic veins pass to the fossa for vena cava on 2 posterior surface of the liver, towards which they converge, taking









886


A MANUAL OF ANATOMY


up sublobular veins in their course. The passages which contain t veins are known as the hepatic canals. On arriving at the upper p; of the fossa for vena cava they are reduced to two or three in numb which pour their contents directly into the inferior vena cava. It is be noted that the hepatic veins converge to the fossa on the poster surface, whilst the branches of the portal vein radiate in all directic from the portal fissure. The hepatic veins are accompanied only lymphatic vessels, and are surrounded by a very scanty amount areolar tissue, which explains why they present open mouths when c across.

Distinguishing Characters of the Hepatic and Portal Veins—Hepatic Veins

(i) These present open mouths when cut across. (2) They are accompan only by lymphatic vessels. (3) Their walls are very thin, and are practica in direct contact with the substance of the liver. (4) They converge towa: the caval fossa on the posterior surface.

Portal Veins. —(1) The mouths of these veins are practically closed or c lapsed when cut across. (2) The veins are accompanied by branches of hepatic artery, and by ducts. (3) Their walls are fairly thick, and are separa from the substance of the liver by the sheaths derived from Glisson’s capsi (4) They radiate in all directions from the porta hepatis in portal canals.

Hepatic Cells.— These are situated within the lobules. 1 hey c polyhedral, granular cells, having a diameter of T 7 T u_ inch, and ea contains a round nucleus. They have no cell-wall, properly so call* and they are connected by a delicate supporting tissue. Ihe ce. which are capable of amoeboid movement, lie between and around t capillary vessels, where they are arranged in radiating rows convergi towards the centre of the lobule.

Bile-ducts. —These commence within the lobules as bile-capillar or bile-canaliculi , which are in reality intercellular passages. Th have a very delicate wall, and are bounded on all sides by the hepa cells—hence the name intercellular passages. According to Pflih and Kupffer, the cells contain vacuoles, which communicate by int: cellular passages with the bile-capillaries. The hepatic cells intern between the bile-capillaries and the capillary bloodvessels. At t circumference of the lobule the bile-capillaries pass into the sm interlobular bile-ducts. These join to form larger ducts, and these turn go on joining until, on arriving at the porta hepatis, only t ducts result, which emerge one from each lobe. These now join to fo: the common hepatic duct, and this joins the cystic duct to form the bi duct. The walls of the interlobular ducts are very thin, being co posed of a basement membrane lined with polygonal epithelium. Tlarger ducts in the portal canals have thicker walls, which, from withe inwards, are composed of a fibro-elastic coat, containing plain muscu tissue, arranged longitudinally and circularly, and a mucous coat lir with columnar epithelium. The mucous membrane of the larger du< presents numerous openings, which lead into blind mucus-secreti recesses. The structure of the hepatic and bile-ducts is similar to t preceding, though on an increased scale.


THE ABDOMEN


v,HEP


887

Lymphatics.—The lymphatic vessels of the liver are arranged in 0 groups—superficial and deep.

Superficial Lymphatics.—These form plexuses beneath the perileal coat, and have different destinations.

Supero-anterior Surface. —(1) The lymphatics from the vicinity of 3 falciform ligament enter that ligament, and, passing through the iphragm into the thorax, they terminate in the anterior group of the pradiaphragmatic glands. (2) The lymphatics from the right part the superior surface and those from the right lateral surface enter 3 right triangular ligament, and, ssing through the diaphragm, they -minate in the middle group of the perior diaphragmatic glands of the r ht side. (3) The lymphatics from 3 left part of the superior surface d those from the left extremity ter the left triangular ligament, and ss to the peri-cesophageal glands in ation to the lower end of the >ophagus, the efferent vessels of lich terminate in the cceliac glands.

1 The lymphatics from the anterior rt of the supero-anterior surface, cept those from the vicinity of the ciform ligament, turn round the terior border of the liver, and end the hepatic glands within the lesser lentum. (5) The lymphatics from ^ 517 ' Lymph Glands in the

e posterior surface of the right lobe Rouviere). ss between the two layers of the HEP, hepatic group,round the artery ronary ligament, and, having pierced and concerned with deep hepatic e diaphragm, they terminate in the na caval group of diaphragmatic mds within the thorax.

Inferior Surface. — (1) The lymtatics from the greater part of the ferior surface of the right lobe, intding those of the quadrate lobe, ss to the hepatic glands. (2) The lymphatics from the posterior ad of the inferior surface of the right lobe pierce the diaphragm, td end in the caval glands. (3) The lymphatics from the greater ad of the caudate lobe pierce the diaphragm, and end in the caval mds ; whilst those from the lower part of this lobe pass to the hepatic mds. (4) The lymphatics from the inferior surface of the left lobe ss to the hepatic glands.

Deep Lymphatics.—These vessels form two distinct sets. Some them accompany the branches of the portal vein, and having emerged rough the porta hepatis, they terminate in the hepatic glands. Others


drainage; B, a cystic gland above, and (below) a gland connected with this and with the retroduodenal gland ; D, above the head of pancreas. These glands are njore particularly concerned with the drainage of the system of biliary ducts.







888


A MANUAL OF ANATOMY


pass with the hepatic veins to the caval fossa of the liver, and thereal they enter the thorax along with the inferior vena cava, their destinat being the caval glands.

Nerves.—The nerves of the liver are derived from the hepatic plex which is an offshoot of the coeliac plexus. The coeliac plexus, thoi principally composed of sympathetic fibres, is reinforced by a 1 twigs from the right vagus nerve. The hepatic plexus accompanies hepatic artery to the porta hepatis, where it receives branches from left vagus nerve, which have ascended from the antero-superior surf of the stomach between the two layers of the lesser omentum. In liver the nerves, which are chiefly non-medullated, are distributed the walls of the bloodvessels and ducts, penetrating as far as the inf spaces between the hepatic cells.

Development of the Liver.

Liver. —The hepatic cells and the epithelium of the bile-ducts are of er dermic origin, whilst the connective tissue of the gland and its vascular c stituents are developed from the mesoderm.

The rudiment of the liver appears as a longitudinal groove on the inner asp of the ventral wall of the duodenal portion of the primitive gut. This gro<


Fig. 518.— Sagittal Section through Septum Transversum and Caud End of Fore-gut in an Embryo of 4-5 Mm., to show Hepatic Divi

TICULUM AND GROWTH OF HEPATIC CYLINDERS AND GALL-BLADDER.

The cylinders have broken up the vitelline veins, represented here by the por vein, into sinusoids. The entoderm is shown by solid black.

gives origin to a diverticulum or evagination of the entoderm of the vent duodenal wall, called the hepatic diverticulum or liver-bud, which has at firsi wide communication with the gut. At a later period this communication becon constricted, and forms a pedicle, which, after undergoing elongation, gives r to the bile-duct. From this pedicle, close to the duodenal wall, the venti diverticulum of the pancreas arises.





THE ABDOMEN


889


The hepatic diverticulum or liver-bud invades the lower or caudal layer of septum transversum, composed of mesoderm, within which it bifurcates > two divisions, the right and left hepatic ducts.

The cells of these two divisions of the hepatic diverticulum undergo proration within the mesoderm of the lower layer of the septum transversum, thereafter each division breaks up into a number of solid trabeculae, which known as the hepatic cylinders. These cylinders give off secondary solid Deculae, and these again ramify extensively. The subdivisions of the various eeculae anastomose freely, and in this manner intricate networks are formed und the vitelline and umbilical veins, which veins traverse the septum isversum as they pass to the sinus venosus. The hepatic cylinders invade se veins, carrying the endothelial walls of the vessels before them. The is are thus freely subdivided into ad-channels, which are known as sinuIs. These sinusoids form capillary works, which occupy the meshes of net-works formed by the hepatic inders.

Many of the solid trabeculas become •ular, and give rise to the bile-capiles or bile-canaliculi, and bile-ducts.

iers give rise to the hepatic cells.

3 liver thus consists originally of incite reticula of solid cellular trabeculce, hepatic cylinders, disposed around the lline and umbilical veins.

As the liver increases in size it profs downwards, carrying with it the r er layer of the septum transversum, ich forms its capsule and connective

ue. The organ now lies between the a layers of the ventral mesentery, ich gives rise to—(1) the falciform iment; (2) the coronary ligament; and the lesser omentum (see p. 79).

About the middle of intra-uterine life

liver occupies a large part of the lominal cavity, and the right and left >es are of equal size. In the latter If of intra-uterine life, however, the ht lobe gradually attains greater size in the left. About the period of birth s liver extends almost as low as the ibilicus. After birth it undergoes dimition in size, the circulation of placental >od through it by the umbilical vein having been permanently arrested at th. The liver decreases in relative size largely owing to slower growth, but ire is also actual degeneration of part of its substance already formed. This plains the occurrence of degenerated remnants, vasa aberrantia and Kiernan s 1 ules, found near its edge, in the left triangular ligament and by the inferior tia cava.

At an early period in development the liver has indications of four lobes, 0 vitelline and two umbilical, but these are not so well marked as in some ier animals. The umbilical lobes form the two lateral lobes, but the vitelline )es are lost in the parts round the vena cava. The other small lobes on the

ceral surface are secondary, formed round large vessels or from surface relays; the free extremity of the caudate lobe has a small process which is the nnant of a part originally projecting into the bursa omentalis through its sning.


Fig. 519. —The Excretory Apparatus of the Liver.

G, gall-bladder; F, fundus; CD, cystic duct; H, common hepatic duct; B, bile duct; P, pancreatic duct; A, ampulla in duodenal wall into which both ducts open.



8 go


A MANUAL OF ANATOMY


The hepatic cylinders appear solid, but they contain no doubt poten lumina. These become apparent as bile-capillaries about the beginning of fourth month.

Hepatic lobules are not well formed before the first few years after bi] They are produced as a result of growth and branching of terminal twigs of hepatic veins, round which the cylinder cells group themselves, with their po vessels.

Structure of the Gall-bladder. —The wall of the gall-bladder composed of three coats—serous, fibro-muscular, and mucous.

The serous coat is formed by the peritoneum, and is usually inco plete, being confined to the inferior and lateral surfaces. Son times, however, the peritoneum completely surrounds the organ, a attaches its superior surface to the fossa for gall-bladder of the liver a ligamentous fold.

The fibro-muscular coat is composed of fibrous and plain muscu tissues. The fibrous bands are disposed in all directions, and int lace freely with one another. The muscular fibres, which int

mingle with the fibre bands, are arranged be longitudinally and trai versely. Around the t minations of the bile-di and pancreatic duct a their continuation ir the ampulla the circul muscular fibres are abr dant, forming the sphino of Oddi (Fig. 520).

The mucous coat covered by columnar ej tfiehum. Its surface presents a great number of small ridges, whi interlace in all directions and enclose polygonal depressions or alve of various sizes. This pitted appearance bears a resemblance honeycomb, and the mucous membrane of the seminal vesicle of t male is similarly arranged. The mucous coat is richly provided wi mucous glands. In the neck of the gall-bladder, which describes t\ cui ves, there are two fibro-mucous folds, which project into the interie one opposite each curve, and serve as valves.

Structure of the Cystic Duct. —The wall of the duct is compos* of a fibro-elastic and muscular coat and a mucous coat. The form 1 esembles that of the gall-bladder. The mucous coat, which is cover* Li' co ^ umnar epithelium, presents several crescentic folds dispos* obliquely round the wall in a spiral or somewhat corkscrew manne and succeeding each other at frequent intervals. When the duct distended, its exterior presents a series of spiral constrictions wii intervening swellings. The spiral folds in the interior serve as valve which are known as the spiral valve (valves of Heister).

Blood-supply. —The gall-bladder is supplied by the cystic arter which is a branch of the right division of the hepatic. Its cour:


Sph. of Pancreatic Duct


.Sph. of Bile Duct


r ^ Longitud. Fibres

Duodenal Pap.

Iug. 520.—Sphincter of Oddi (after


Hendrickson).



THE ABDOMEN


891


forwards between the hepatic and cystic ducts to the neck of the gan, where it divides into two branches, superior and inferior. ie superior branch ramifies on the upper surface of the organ, between and the fossa for gall-bladder of the liver, whilst the inferior branch distributed over the inferior surface beneath the peritoneum. The stic vein, which is formed by the union of superior and inferior anches, usually opens into the right division of the portal vein. >me of the veins from the gall-bladder may enter the liver to join e right branch of the portal vein. This fact explains the venous emorrhage which sometimes occurs when the gall-bladder is lifted it of its fossa.

Lymphatics. —These pass between the two layers of the lesser nentum to the hepatic glands.

Nerves. —These are derived from the hepatic sympathetic plexus.

Development of Gall-bladder and Duct.— An early stage is seen in Fig. 518. ie hepatic diverticulum is elongated in the line of the gut, and its lower end dilated to form the gall-bladder, the upper part alone giving origin to hepatic linders. The lower part of the groove is blocked by cell-growth, the bladder us opening into the upper part which will become the liver-duct. The bladder; latation grows ventrally in the mesoderm below the liver, its neck thus being retched out between the duct and the bladder, and becoming the cystic duct.


Structure of the Pancreas.

The pancreas belongs to the class of compound racemose or acinolbular glands, and bears a close resemblance to a serous or true ilivary gland— e.g., the parotid. It has a greyish-pink colour, and somewhat soft in consistence. It is from 6 to 8 inches long, from to 1^ inches deep, except at the right and left extremities, and from to | inch thick. Its weight is about 3^ ounces. It is destitute of fibrous capsule, properly so called, and is invested merely by a thin onnective-tissue covering, which readily allows the outline of the )bules to be seen.

It is composed of a number of lobules, which are loosely held ogether by ducts and areolar tissue. Each lobule consists of a group f alveoli or acini which are long, tubular, and convoluted, wherein hey differ from the saccular alveoli of such a gland as the parotid. Tom each lobule a duct passes off, which unites with the ducts of djacent lobules in the left extremity of the gland to form the commencement of the principal duct. Within the lobule the lobular duct 5 formed from junctional ducts, each of which belongs to an acinus, nd is lined with flattened cells.

The alveoli or acini are each composed of a basement membrane, eticular in structure, and lined with secreting columnar epithelium, he basement membrane being continuous with the wall of the junctional luct. The lumen of each acinus is small, and is usually occupied by pindle-shaped cells, known as the centro-acinar cells of Langerhans, vhich are continuous with the cells of the junctional duct, dhe


892 A MANUAL OF ANATOMY

connective tissue which covers the pancreas sends expansions inw between the lobules, along which the bloodvessels are condu( Further, the interlobular connective tissue penetrates into the lob and so conducts the bloodvessels into their interior. The interalv i

connective tissue has a loose position, and in certain parts tains small groups of epithelium cells, surrounded by large convol capillary vessels. These gr< constitute the islets of Langerh which are characteristic of pancreas.

Excretory Apparatus of the 1 creas. —There is one principal d called the pancreatic duct (due Wirsung). It is buried in the i stance of the gland, and is rea recognized by its white colour, lies nearer the posterior than anterior surface, and rather ne; the lower than the upper part of gland. It commences in the whence it runs through the b as far as the neck, receiving in course a great many tributai On arriving at the neck it eff< a communication with the ac< sory pancreatic duct, then descri a bend, and passes into the head in a direction downwards, backwai and to the right. Finally, on leaving the pancreas it meets the t duct, and the two, entering the wall of the second part of the duodem terminate in the manner already described (see p. 779).

The accessory pancreatic duct (duct of Santorini) is comparativ small, and varies much in size. If well developed, it commen in the lower part of the head, where it takes up the ducts of the lobi of that part. It then passes upwards with an inclination to the right, c divides into two branches. One of these joins the pancreatic main d 1 in the neck, whilst the other opens into the second part of the duoden at a point about 1 inch above the common opening of the bile-di and the pancreatic duct. The secretion conveyed by the access( duct is believed in early life to flow into the duodenum, whereas in 1 adult it is largely diverted into the pancreatic duct.

The tributaries of the principal duct, as well as of the accessc duct, when followed into the pancreas, become in succession int lobular and intralobular ducts. The intralobular ducts pass wit! the lobules, and end in intermediary , junctional, or intercalary* due with which the alveoli or acini are directly connected. The p£

Interposed or inserted between the alveoli and the intralobular ducts.


Alveoli Islets of Langerhans


Fig. 521. — Structure of the Pancreas (highly magnified).


THE ABDOMEN


893


he duct between the intermediary and the intralobular duct is 3d the neck. The walls of the intermediary ducts are thin, and formed of a basement membrane covered by flattened epithelial 5, the neck being lined by polyhedral cells. In the larger ducts Dnnective-tissue coat is superadded to the basement membrane, ch is now covered by columnar epithelium. The pancreatic duct, igh of comparatively large size, has a thin wall destitute of muscular 3s except near its termination, and composed of two coats— irnal fibrous and internal mucous. The mucous coat is smooth and ered by columnar epithelium.

Varieties— (1) Small Pancreas. —This consists in a permanent detachment he unciform process, or that part of the pancreas which extends along the er aspect of the third part of the duodenum and has the superior mesenteric els in front of it. (2) The head of the pancreas may surround the second

of the duodenum more or less completely. (3) Accessory Pancreas.— n an accessory pancreas is present it is usually met with in the wall of the

Fig. 522.—The Pancreas and its Ducts (Posterior View).

A

>er part of the jejunum, but it may be found in the wall of the stomach or >er part of ileum. (4) The pancreatic duct sometimes opens into the duodenum 3 pendently of, but close to, the bile-duct.

Blood-supply. —The pancreas derives its arteries from (1) the lcreatic branches of the splenic artery, one of which accompanies principal duct from left to right, and is known as the arteria panitic magna; (2) the superior pancreatico-duodenal of the gastro)denal from the hepatic; and (3) the inferior pancreatico-duodenal

he superior mesenteric. The veins are (1) the pancreatic veins, which open into the splenic n; and (2) the pancreatico-duodenal veins, which terminate in

superior mesenteric or portal veins. All the pancreatic venous od eventually passes into the portal vein.

Lymphatics. —These commence as lymphatic clefts around the eoli, and pass chiefly to the cceliac glands. Some of them, however, minate first in the superior mesenteric glands in contact with the per part of the superior mesenteric artery.

Nerves. —These are derived from offshoots of the hepatic, splenic, i superior mesenteric plexuses, and accompany the arteries. They 5 chiefly composed of non-medullated fibres.


Uncinate Process


Pancreatic Duct


Pancreatic Duct


Accessory Duct


Bile Duct



894


A MANUAL OF ANATOMY


Development of the Pancreas. —The tubular portion of the pancreas entodermic origin, but its connective tissue and vascular elements are deve from mesoderm.

The pancreas is developed from two entodermic diverticula—dorsa ventral. The dorsal diverticulum is an evagination of the entoderm of the wall of the duodenal portion of the primitive gut. The ventral diverti( springs from the primitive hepatic diverticulum close to the ventral wall ( duodenum, which diverticulum subsequently forms the bile-duct. The < diverticulum extends between the two layers of the meso-gastrium, wh comes into relation with the developing spleen. This diverticulum giv lateral epithelial tubes, which ramify freely, and so build up an acino-tu


Fig. 523. —Diagram to show the Relations of the Pancreatic Outgrowths to the Median Mesentery.

The dorsal wall of the duodenum is left on the meso-duodenum, and bet this and the oesophagus the stomach has been removed with the front of the bursa omentalis, leaving the posterior wall and opening of the The ventral outgrowth A is growing in the meso-duodenum, but the d growth, being higher up, is able to extend into the wall of the primitive The portal vein passes backwards, upwards, and to the right betweei two outgrowths.

gland. The acini appear as enlargements of the walls of the terminal t By means of the ramifications of the dorsal diverticulum the greater part o head, body, and tail of the adult pancreas are formed.

The ventral diverticulum is at first double, right and left outgrowths ar from the liver-hud. The left formation quickly disappears, while the right coming into relation with the portal vein, grows round this into the meso-duode\ where it enlarges, being placed with the vein behind the duodenum as this ci out toward the right. It forms the pancreatic duct, and gives outgrowtl form the lower part of the head of the pancreas.

The ventral and dorsal parts of the pancreas join, and the dorsal d ticulum (pancreatic duct) and ventral diverticulum now communicate by fi anastomosing branches. Thereafter the duodenal portion of the pancr»










THE ABDOMEN


895


ict usually atrophies and disappears. It may, however, persist, and open as l independent duct into the second part of the duodenum. The accessory iiicreatic duct is persistent, and constitutes the principal duct of the fully iveloped pancreas. From its mode of development it necessarily opens into e bile-duct.

The islets of Langerhans, which are characteristic of the pancreas, are formed cells derived from the walls of the original epithelial tubes. These cells become fferentiated, and by their multiplication they give rise to isolated cell-groups, ing in the mesodermic connective tissue between the lobules of the gland, where ey are soon permeated by bloodvessels.

The development of the head of the pancreas proceeds within the meso-duonum (Fig. 523) dorsal and caudal to the vitelline vein, which enters the mesolodenum here to form the beginning of the portal vein. The head, by its large owth, widens out the meso-duodenum to a very considerable extent, and oduces the curve of the duodenum round its mass. The body and tail of the gan extend into the dorsal wall of the bursa omentalis, growing rapidly in this ward the left. They thus come to be directed transversely, and are laid down the dorsal wall of the abdomen. When the peritoneum of this wall adheres the bursal wall, and the two adherent layers disappear, the gland is left in a ro-peritoneal position behind the completed lesser sac; rarely, however, the hesion and disappearance of the layers is incomplete, and thus a cyst may be

med behind the gland from fluid within a persisting part of the peritoneum re.


Structure of the Spleen.

The spleen is the largest ductless gland in the body. It has two ats, serous and fibrous, inseparably connected together. The serous at is formed by the peritoneum. The fibrous coat or tunica propria composed of fibrous tissue, with a considerable admixture of elastic

sue, and a certain amount of plain muscular tissue, all of which lild up a strong distensible tunic.

The organ is composed of a trabecular network, the spleen pulp, oodvessels, and Malpighian corpuscles.

The tunica propria sends into the organ a number of trabecube fich, like the tunica propria, are composed of fibrous, elastic, and ain muscular tissues. These divide and subdivide, and unite with e another, as well as with processes derived from the sheaths which e bloodvessels carry in with them at the hilum. There is thus pied a trabecular network, which pervades the interior, and conins in its meshes the splenic pulp, capillary tufts, and lymphatic 'dules.

The splenic pulp occupies the meshes of the network formed by the ibeculae. It is soft, and has a dark red colour, which, however, comes brighter on exposure to the air. The matrix of the spleen [ lp is reticular, and is formed by branched connective-tissue coracles, which constitute the sustentacular cells of the organ, the drix is, therefore, in reality retiform tissues. The interstices of e reticulum contain blood, in which there is a large number of white rpuscles, and also special cells characteristic of the spleen, and fied the splenic cells. These latter are of large size, and are amoeboid. iey contain pigment, and red blood-corpuscles in various stages of integration.


8 g6


A MANUAL OF ANATOMY


Bloodvessels and Lymphatic Nodules (Malpighian Corpuscle! Arteries.—The splenic artery furnishes five or six large branches wl enter the organ at the hilum, and carry in with them trabecular shea from the tunica propria. In the interior they divide and subdiv and finally terminate in pencil-like clusters of capillary vessels, which time they have laid aside all their coats except the endotht lining. The endothelial cells then become separated from each ot by spaces, and being continuous with the sustentacular cells of spleen pulp, the blood flows directly into the interstices of the reticu] of the pulp. The arteries, which are at first accompanied by trabeci sheaths, ultimately lose these sheaths, and enter the splenic pulp

end in clusters of capillaries, fore they terminate in these c' ters their external coat underg an important modification, wl consists in its transformation i lymphoid or adenoid tissue. 1 lymphoid tissue forms at inten small round or oval enlargemei called lymphatic nodules (Ma ghian corpuscles), which on sect appear as minute white speck; the dark red spleen pulp. Tb corpuscles are simply local! expansions of the lymphoid tis which forms the external coat the small arteries. The expans may be confined to one side the artery, or it may include whole of its circumference. E; corpuscle receives minute tv from the artery on which it is i and contains large numbers lymph corpuscles, as well capillary bloodvessels.

Veins.—The arterial blood, on leaving the capillary vessels, tie directly into the interstices of the reticular matrix of the spleen pr and from these it is taken up by radicle veins which commence b manner similar to that in which the capillaries end. Endothe cells, continuous with the sustentacular cells of the pulp, come togetl and cohere, so as to form very delicate tubular vessels having clo! walls. As these radicle veins unite and become larger the other co are superadded to the endothelial lining. Ultimately five or six ve leave the spleen at the hilum, which unite to form the splenic vei

this in turn uniting with the superior mesenteric vein to form the poi vein.

It is to be noted that, in the circulation through the spleen, j arterial blood leaves tubular vessels and flows through the interstij


Capsule Trabecula


Lymphatic Nodules Splenic Pulp


Fig. 524. —Section of the Spleen.








THE ABDOMEN


897


he reticulum of the spleen pulp, where it bathes the Malpighian niscles, after which it enters tubular vessels of the nature of veins, rhe cells of the spleen are of three kinds as follows: (1) the sustenilar cells of the retiform tissue of the spleen pulp; (2) the splenic>; and (3) lymphoid corpuscles.

Lymphatics. —These are arranged in two groups—trabecular and vascular. The trabecular lymphatics are contained in the trails, and communicate with a lymphatic network in the tunica pria underneath the peritoneal coat. The perivascular lymphatics mence in the lymphoid tissue which forms the external coat of smaller arteries. At the hilum both sets of lymphatics meet and 3 to the splenic glands, and thence to the coeliac glands.

Nerves. —These are derived from the splenic plexus, which is an hoot from the coeliac plexus. The fibres, which are mostly nonLullated, are derived partly from the sympathetic system and partly n the right vagus nerve.

)evelopment of the Spleen. —The spleen is formed from the mesodermal of the bursa omentalis. In the fifth week the sac wall in its upper, dorsal, left part shows a certain amount of thickening, with vascularization, and 2ase in size of the mesothelial cells covering its outer surface. A little later e covering cells proliferate, and cells pass from the layer into the mesenchyme le wall. As the mass enlarges it projects outwards into the peritoneal cavity.

he processes take place at several points the organ is lobed; although the d appearance is lost by subsequent fusion, the original divisions are indicated

he fissures. The cells arrange themselves in trabecular bands, and small gather round the small branches of the splenic artery and form the lymphatic lies (Malpighian corpuscles) about the seventh month. When the dorsal of the bursa omentalis becomes adherent to the wall of the abdomen, the sn, lying just outside the area of adhesion, is now attached to the outer edge his area by the intervening strip of non-adherent sqc wall— i.e., by what is wn as the lieno-renal fold. As it projects toward the left, away from the ty of the sac, it is covered by peritoneum of the greater sac, and is separated 1 that of the lesser sac by the vessels in the wail of the latter.


Structure of the Suprarenal Glands.

The suprarenal glands [adrenals) belong to the so-called ductless ids. Each gland is enclosed in a thin sheath of connective tissue, n the deep part of which processes are given off into the interior, ire they form a supporting stroma. The proper substance of the id is divided into an external or cortical, and internal or medullary t.

The cortex has a somewhat yellowish tint, due to the presence of poid substance, and is composed of cells supported by a fibrous )ma. The cells being variously arranged in different parts, the tex is divisible into three zones, named, from without inwards, zona nerulosa, zona fasciculata, and zona reticularis. The zona glomerul > which is narrow, lies immediately within the external capsule, I- is so named because its component cells are grouped in such tanner as to form glomeruli, which are embedded in a fibrous stroma.

57


898


A MANUAL OF ANATOMY


The cells are polyhedral, and each contains a clear round nucl The zona fasciculata forms the chief part of the cortex, and is so na] because its component cells are arranged in columns or fasciculi, cells are similar to those of the zona glomerulosa, and the cell coin are separated from one another by fibrous trabeculae, which aci carriers of the bloodvessels, nerves, and lymphatics. The zona ret laris, which is narrow, lies within the zona fasciculata, and is so nai because its component groups of polyhedral cells are connected \ one another in such a manner as to form a reticulum.

The medulla is confi


Capsule \


Cortex


Medulla


Zona Glomerulosa


> Zona Fasciculata


Zona Reticularis


Fig. 525. —Section of the Suprarenal

Capsule.


to the centre of the gl in the adult, is soft in c sistence, and has a redd brown colour, due to contained venous blood, supporting fibrous strom; the cortex pervades it, ; is arranged in a retici manner. The meshes of 1 reticulum are occupied cells, larger and more irre lar than those of the corl further differing from tf in containing granules wf stain deeply with chromi salts.

Blood-supply—Arteries

These are (1) the supei suprarenal of the phre from the abdominal aoi (2) the middle suprare from the abdominal aoi and (3) the inferior sup renal from the renal.

The veins of each gh eventually unite to form <


suprarenal vein. This vessel emerges through the hilum, and on right side it opens directly into the inferior vena cava, whilst on left side it terminates in the left renal vein.

The lymphatics terminate in the juxta-aortic glands . The lyi vessels accompany the vessels connected with the glands. T1 issuing with the main vein drain the medullary region, and ] (Fig. 526) to aortic glands below the levels of the renal pedicles; on two pass behind these to glands behind the renal arteries. Yes accompanying the suprarenal arteries drain the cortex, and reach gla above the renal pedicles; on the right some pass behind the infe vena cava. Additional lymphatics, shown in the figure by interruj lines, run up on the diaphragm, which they pierce, to enter glands

















THE ABDOMEN 899

thoracic aorta at about the level of the ninth or tenth thoracic tebrae.

Nerves. —-The suprarenal glands are very richly supplied with nerves, ch are derived from (1) the phrenic plexus from the coeliac ganglion . coeliac plexus, (2) the suprarenal plexus from the coeliac ganglion . coeliac plexus, and (3) offshoots from the renal plexus. According Bergmann, the suprarenal glands also receive fibres from the phrenic . vagi nerves. The fibres, which are chiefly non-medullated, form l plexuses in the medulla, where they have numerous ganglion cells nected with them.


Fig. 526. —Lymphatics of Suprarenal Glands (after Rouviere).

Development. —The suprarenal gland makes its appearance medial to the •onephros. The cortex is of mesodermic origin, and the medulla is developed n the cells of the primitive abdominal sympathetic system.

The cortex is developed from cellular outgrowths of the mesothelium of the om, or body-cavity, on the mesial aspect of the mesonephros. These outwths soon become separated from the ccelomic mesothelium, and unite to n a solid mass, which constitutes the cortex.

The medulla is derived from the primitive abdominal sympathetic cells, 'ups of cells grow out from the ganglia (these cells being consequently of Mermic origin), and they invade the cortex. They become differentiated ^ two groups. The cells of one group are chromaffivi cells, and stain a dark ow colour with chromic acid salts. The cells of the other group are ganglion All the cells developed from the sympathetic ganglia gradually pass to the tre, where they constitute the medulla.



900


A MANUAL OF ANATOMY


The suprarenal gland thus develops in two parts—cortex, derived fron coelomic mesothelium (mesoderm), and medulla, derived from the abdor sympathetic ganglia, and therefore of ectodermic origin. The cortical begins to form in the fourth week, and the ganglion cells begin their inv: three weeks later; the process goes on till after birth, and ill-understood fc tive changes continue for some years.

Structure of the Kidneys.

The kidneys are compound tubular glands. Each organ is vested by a capsule, composed of fibrous tissue with a certain aim of elastic fibres. The deep surface of this capsule is attached tc peripheral portion of the renal substance by fine fibrous processes

small bloodvessels. Ur neath it there is a cei amount of plain muse fibre, arranged in a sc what plexiform manner, the hilum on the inner bo it is prolonged inwarck line a cavity to which hilum leads, called the t sinus, where it becomes tinuous with the fibrous c of the calyces.

When a kidney is into two halves by a lc tudinal incision carried f the outer to the inner bo it is seen to be comp< of two parts—cortex medulla.

The medulla, whicl internal in position, is ranged in conical bum termed renal pyramids (pyramids of Malpighi), which vary in nun from eight to eighteen, the average number being about twe The bases of these pyramids are directed towards the circumfere: whilst their apical parts, called renal papillae, project into the sinus, wl they are grasped by the calyces. Each renal pyramid is divided : three parts—namely, the basal part, the papillary zone, and the a ; The basal parts of the pyramids form collectively the boundary zon the kidney. They abut against the cortical substance, which se prolongations between them, called renal columns (columnar BerU These prolongations extend as far as the commencement of the ap parts of the papillary zones, where they cease, so that these ap parts project into the calyces free from cortical investments. E renal pyramid is composed of straight, slightly converging urinifei tubules (tubuli recti ) and straight bloodvessels, the number of tub


Renal Pyramid


Calyx


-Pelvis


— Ureler


Fig. 527.—Diagram of the Kidney in Longitudinal Section.




















THE ABDOMEN


901


ig very much greater in the basal part than elsewhere. This ight arrangement of tubules and bloodvessels imparts to each amid a longitudinally striated appearance from apex to base. The al parts have a dark reddish-brown colour, which becomes brighter he papillary zones.

The cortex of the kidney is mainly situated within the fibrous sule. It has a reddish-brown colour, and, as already stated, sends longations between the renal pyramids. Like the medullary part,

composed of uriniferous tubules and bloodvessels, but the tubules principally convoluted (tubuli contorti), though there are also dies of straight tubules (tubuli recti) which have issued from the il pyramids, and form the medullary rays.

Cortex. —The cortical part is composed of the labyrinth and the lullary rays.

Labyrinth .—This portion of the cortex is so named from the very iplicated arrangement of its tubules. It is situated in the internes between the medullary rays, and is composed of convoluted dferous tubules, bloodvessels, and glomeruli, each of the latter being losed within a capsule of Bowman.

Uriniferous Tubules. —Each tubule commences in the labyrinth he cortex in a spherical dilatation, called the capsule of Bowman, tiin which there is a tuft of convoluted capillary bloodvessels, known i Malpighian glomerulus (Malpighian corpuscle). Bowman s capsule sents two poles. One of these is formed by two bloodvessels, afferent efferent, which pierce the capsule at separate points, but close to each er. At the other pole Bowman’s capsule becomes constricted, and ns the neck of a cylindrical tubule. After the tubule has passed the k it becomes convoluted, and forms the first convoluted tubule. The


sment membrane and lining epithelium of Bowman’s capsule are conious with the basement membrane and lining epithelium of the first voluted tubule, and the space between Bowman’s capsule and the nerulus is continuous with the lumen of the tubule. The first voluted tubule soon becomes straight, though slightly wavy, and, Ting a medullary ray, it forms the spiral tubule. This tubule, on 'hing the junction of the cortex and boundary zone, becomes denly very narrow, and traverses the basal part of a renal pyramid, s known as the descending limb of Henle’s loop. On leaving the ndary zone it enters the papillary zone, and after a short course escribes a very sharp bend, called the loop of Henle. It now re'es its steps from the papillary zone into the boundary zone of a al pyramid, in which latter situation it becomes suddenly enlarged, s part, which retraces its steps, is called the ascending limb of Henle’s »• It re-enters the cortex, where it becomes narrower, and passes > a medullary ray, in which it lies for a short distance. It subaently, however, leaves the ray, and, entering the labyrinth, ds between the convoluted tubules as the irregular or zigzag tubule, ch has become slightly enlarged. This irregular tubule then passes 1 the second convoluted tubule. This tubule, becoming narrow,


go2


A MANUAL OF ANATOMY


passes into the junctional tubule, which is slightly wavy. The tional tubule leads into the straight or collecting tubule, which is slij enlarged, and is situated in a medullary ray. This straight colle tubule now passes to the basal part of a renal pyramid, taking i


Fig. 528. —Diagram of the Uriniferous Tubules of the Kidney (Ki

a and a', outer and inner zones of cortex, which are free from

Malpighian bodies.

1. 1. Capsule of Bowman 4. 4. Spiral Tubule

2. 2. Neck of Capsule 5. 5. Descending Limb of Henle’s Loop

3. 3. First Convoluted Tubule 6 6. Loop of Henle

7. 7., 8. 8., 9. 9., Ascending Limb of Henle’s Loop

10. 10. Irregular Tubule 13. 14. Collecting Tubule

11. 11. Second Convoluted Tubule 15. Duct of Bellini

12. 12. Junctional Tubule


its course other junctional tubules from the labyrinth. In pa through the various parts of a renal pyramid the collecting tu unite at acute angles, and so become less numerous and at the same larger. They run in straight, slightly converging lines toward




















THE ABDOMEN


903


x of a papilla, where they are very much reduced in numbers, but of (e size. In this final part of their course each collecting tubule ns the duct of Bellini. These excretory tubes open on the apex of ipilla, where there is often a foveola or small depression, and through se openings the urine escapes into a calyx.

The diameter of the ducts of Bellini is about inch.

Summary of a Tubule from Beginning to End.

[. The capsule of Bowman, containing a glomerulus in the labyrinth .

>. The neck, in the labyrinth.

5. The first convoluted tubule, in the labyrinth. j.. The spiral tubule, in a medullary ray.

5. The descending limb of Henle’s loop (small), in a basal part, and in part papillary zone, of a renal pyramid.

). The loop of Henle, in a papillary zone.

7. The ascending limb of Henle’s loop (large), in part of a papillary zone, a l part, and the cortex, in which latter it is in a medullary ray.

The irregular or zigzag tubule, in the labyrinth.

). The second convoluted tubule, in the labyrinth.

o. The junctional tubule, in the labyrinth on its way to a medullary ray. [i. The collecting tubule, in a medullary ray of the cortex, and in a basal part renal pyramid.

[2. The duct of Bellini, in a papillary zone of a renal pyramid.

Structure of the Uriniferous Tubules. —The tubules are composed of a baset membrane lined with a single layer of epithelial cells. The basement ibrane itself consists of flattened epithelial cells. The tubules vary in but their average diameter may be stated as inch. The characters he lining epithelial cells present differences in the different tubules, which now be considered in order.

[. The capsule of Bowman is lined with a single layer of flattened epithelium,

h is reflected over the glomerulus, where it is more distinct in early life than ie adult.

-• The neck is lined with cubical epithelium.

5. The first convoluted tubule is also lined with cubical epithelium, but the cells,

h are thick, are peculiar. The inner part of each cell—that is, the part next lumen of the tubule—including the spherical nucleus, has granular protoplasm, st the outer part—that is, the part next the basement membrane—has its pplasm striated or fibrillated, owing to the presence of rod-shaped fibrils disposed ically to the basement membrane (Heidenhain). These fibrillated cells are dded laterally with processes by which they embrace one another. The en of the tubule is distinct.

p The spiral tubule is lined with epithelium similar ’to that of the first* conned tubule, and its lumen is distinct.

5- The descending limb of Henle’s loop is lined with clear, thin, flattened cells. tubule, though narrow, has a distinct lumen.

5 . The loop of Henle is lined with epithelium which resembles that of the lending limb.

7- The ascending limb of Henle’s loop is lined with fibrillated, cubical epithelial like those of the first convoluted and spiral tubules. Though it is of comffively large size, its lumen is small.

3 - The irregular or zigzag tubule is lined with cubical epithelial cells, which markedly fibrillated, and its lumen is minute.

3 - The second convoluted tubule is lined with epithelium which resembles t of the first convoluted tubule, with the following differences: (a) the cells longer; and (b) they are highly refractive. In size it corresponds with the ' convoluted tubule.


9o 4 A MANUAL OF ANATOMY

10. The junctional tubule is lined with clear, flattened, cubical epithelial , and its lumen is large.

11. The collecting tubule is lined with epithelial cells, which in its earlier are clear and cubical, but in its later part they are columnar, and the lum< very distinct.

12. The duct of Bellini is lined with epithelial cells which are clear

columnar.

Medullary Rays or Pyramids of Ferrein. —These take the torn pyramidal bundles of uriniferous tubules, which are separated f: each other by portions of the labyrinth. The tubules are straij and emerge from the basal parts of the pyramids. As these medul] rays are followed from the basal parts to the periphery, each gradu diminishes in breadth, and ultimately tapers to a point, which si a short distance from the fibrous capsule, being separated from it a portion of the labyrinth. The rays are thus conical, their bases b( at the basal parts of the renal pyramids, and their apices near the fibi capsule—hence the name ‘ pyramids.’ The explanation of this sh is that the tubules at the circumference of a medullary ray enter labyrinth sooner than those in the centre, which latter form the a of the ray.

Summary of a Medullary Ray. —Each contains the following tubules: (i) sj tubules; (2) ascending limbs of Henle’s loops; and (3) collecting tubules.

Medulla of the Kidney. —The medullary portion has been alre; generally described. It is composed of renal pyramids, consisl of uriniferous tubules and bloodvessels (true and false).

The tubules in the various parts of the renal pyramids are as folio

1. Basal Part. —This contains the following tubules:

Portions of the descending limbs of Henle’s loops.

Portions of the ascending limbs of Henle’s loops.

Collecting tubules.

2. Papillary Zone. —This contains the following tubules:

Portions of the descending limbs of Henle’s loops.

The loops of Henle.

Portions of the ascending limbs of Henle’s loops.

The ducts of Bellini.

3. Apex of the Papillary Zone. —This contains only the ducts Bellini.

Bloodvessels of the Kidneys — Arteries. —Each kidney receives large amount of blood from the renal artery, which is a branch of abdominal aorta. This vessel, as it approaches the hilum, divides i] four or five branches, which enter the sinus, where they are embedc in fat along with the calyces. They then subdivide into interlo' branches, which pass between the renal pyramids, where they contir to subdivide. On arriving at the junction of the cortex and bound; zone they form a series of arches, which are independent of one anotb and are called the cortico-medullary arches. Alongside of these th< are venous arches, which, unlike the arterial arches, anastomose fre<


THE ABDOMEN


905


ith one another. The convexities of the incomplete arterial arches

e directed towards the cortex, and the concavities towards the renal yramids. The branches of the arches are interlobular and arteriae

ctae. The interlobular arteries (cortical) arise from the convexities of the rches and enter the labyrinth of the cortex, in which they pass outards between the medullary rays, hey give off afferent and capsular ranches.

The afferent branches are so named ecause they carry blood to the 'omeruli. They arise from the in^rlobular arteries at frequent interals, and each passes to a capsule f Bowman without giving off any ranch. Having pierced the capsule t one pole, the afferent vessel breaks p into a number of convoluted ipillary vessels, which form a small ascular ball, called a glomerulus Malpighian corpuscle). The blood is onveyed away from the glomerulus y an efferent vessel, which is variously sgarded as an artery and a vein, his efferent vessel is smaller than tie afferent artery. It pierces bowman’s capsule at the same pole s the afferent artery, but separate

om, though close to, it. Therefter it breaks up into a network of apillary vessels, which invest the orresponding first convoluted urinierous tubule, the meshes of the network being polygonal. The efferent r essels of those glomeruli which lie learest to the renal pyramids are iisposed in a different manner. They >reak up into bundles of straight vessels, called false vasa recta, which nter the basal parts of the pyramids, diere they supply to a large extent the uriniferous tubules, upon the mils of which they form capillary networks with elongated meshes, t is, however, to be noted that the renal pyramids also receive true irterise rectae from the cortico-medullary arterial arches.

The Glomerulus (Malpighian Corpuscle). —A glomerulus of the kidney s a small ball of convoluted capillary bloodvessels, having two vessels connected with it, one of which is an afferent artery and the other an 'fferent vessel. The vessels of many of the glomeruli are collected into


VESSELS OF THE KlDNEY.

A, cortex; B, medulla.

1. Arterial Arch

2. Interlobular Artery

3. Afferent Artery of Glomerulus

4. Capsular Branches

5. Efferent Vessel of Glomerulus

6. Glomerulus

7. First Convoluted Tubule

8. True Arteria Recta

9. False Arteria Recta

10. Venous Arch

11. Interlobular Vein

12. Venae Stellatae

13. Venae Rectae

























9o6 A MANUAL OF ANATOMY

bundles, an arrangement which renders these glomeruli tabulated, number of lobules varying from two to five. Each glomerulus within a capsule of Bowman, and the flattened epithelium of the caps is reflected over the glomerulus from the points of entrance and exil the afferent and efferent vessels. The epithelial cells covering the c puscle are thicker and less flattened than those lining the capsule Bowman, and are better marked in early life than in the adult, the case of the tabulated glomeruli the epithelial investment dips between the component lobules. The epithelium of Bowman’s caps and the epithelium of the glomerulus, which in each case forms a sin layer, are separated from one another by a slight interspace. 1

diameter of a glomerulus is about ¥ To * n The glomeruli are confined to the cortex of i kidney, where they lie in rows in the labyrii between the medullary rays. There is a narr zone immediately within the external capsi and another narrow zone close to the re: pyramids, from both of which glomeruli ; absent.

The capsular branches of the interlobu arteries supply the external fibrous capsule the kidney, in which they anastomose w: branches of the lumbar arteries from the c dominal aorta.

The arteriae rectae (medullary), or vasa rec (true), arise from the concavities of the corti( medullary arterial arches, and at once enter t basal parts of the renal pyramids. Here th break up into bundles of straight, sligh diverging arterioles, which run between t bundles of straight, slightly converging uri: ferous tubules, a mutual arrangement whi imparts to the renal pyramids a longitudina striated appearance. The capillary networ formed by these arterioles have necessar: elongated meshes. It is to be noted that t renal pyramids derive their blood-supply frc two sources—namely, (i) the arteriae rectae, or vasa recta (true), frc the cortico-medullary arterial arches; and (2) the false vasa recta frc the efferent vessels of those glomeruli which lie nearest the rer pyramids. It is also to be noted that a glomerulus of the kidney is ball of convoluted capillary bloodvessels, which is enclosed with a capsule of Bowman, whereas a Malpighian body of the spleen is collection of lymphoid or adenoid tissue which is a localized expansi< of the external or lymphoid coat of the small arteries in the interi of that organ.

Veins — Veins of the Cortex. —These are called the interlobular vein Some of them commence on the surface of the kidney beneath tl


showing a Glomerulus OF THE Kidney with its Afferent and Efferent Vessels, and a Proximal Convoluted Tubule with ITS Venous Plexus (Bowman).

1. Glomerulus

2. Bowman’s Capsule

3. Uriniferous Tubule

4. Interlobular Artery

5. Afferent Vessel

6. Efferent Vessel

7. Venous Plexus around

Tubule

8. Interlobular Vein





THE ABDOMEN


907


psule, from which they return blood, and these are called vence stellatce, cause the venous radicles which give rise to them converge to a int, and so present a star-like appearance. Others originate in the sxuses around the uriniferous tubules. The interlobular veins rminate by joining the convexities of the venous arches, which are uated between the cortex and the renal pyramids.

Veins of the Medulla. —The veins of the renal pyramids commence plexuses which surround the ducts of Bellini in the apical parts of the pillary zones, and they are called vencB rectcB. As these traverse the aamids they are collected into bundles of straight vessels, which ien into the concavities of the cortico-medullary venous arches.

Cortico-medullary Venous Arches. —These arches, which are comste, are situated between the cortex and the renal pyramids, where ey lie alongside of the incomplete arterial arches. They derive their Dod from the interlobular veins of the cortex and the venae rectae the renal pyramids. The veins which proceed from these arches „ss between the pyramids to the sinus of the kidney, where they Lite to form the renal vein, which terminates in the inferior vena cava. Lymphatics. —These consist of two groups, superficial and deep, le superficial lymphatics, which are few in number, form a plexus in e fibrous capsule, and communicate with lymph spaces between the iniferous tubules in the outer part of the cortex. They terminate r joining the deep lymphatics at the hilum. The deep lymphatics company the bloodvessels, and communicate with lymph spaces itween the uriniferous tubules of the cortex and boundary zone, n emerging at the hilum they receive the superficial lymphatics, id then pass to the juxta-aortic group of lumbar glands.

Nerves. —The kidney receives numerous nerves from the renal exus, which derives its fibres from (1) the aortico-renal ganglion, which the lesser splanchnic nerve terminates; (2) the coeliac plexus; id (3) the aortic plexus. If there is a lowest splanchnic nerve present reinforces the renal plexus. The nerve-fibres are partly sympathetic, irtly spinal through the lesser and lowest splanchnic nerves, and in irt derived from the right vagus through the coeliac plexus. I hey ^company the arterial branches, and ramify upon the walls of the sssels and uriniferous tubules.

Excretory Apparatus of the Kidney. —This consists of the calyces,

elvis, and ureter.

Ureter. —This is the excretory duct of the kidney, and it has the >rm of a cylindrical tube, like a goose-quill, its colour being a dull hite. Its length varies from 12 to 16 inches, and its diameter is bout 1 inch. At its lower extremity it opens into the bladder, and t the hilum of the kidney it joins the pelvis of the kidney, which is mnel-shaped, being wide above and narrow below. Ihe pelvis is attened from before backwards, and lies partly in the sinus and artly outside the hilum, its direction being downwards and inwards, t is formed by the union of two or three primary divisions or greater alyces (infundibula) within the sinus, and these again are formed by


9o8


A MANUAL OF ANATOMY


the union of about nine secondary divisions, called lesser calyces. 1 number of lesser calyces thus usually falls short of the number of re pyramids (8 to 18), the explanation being that one lesser calyx n grasp two papillae or even three. The lesser calyces embrace i papillae of the renal pyramids, which thus project into them, and tl receive the urine as it oozes through the pores on the apices of 1 papillae, these pores being the openings of the ducts of Bellini. 1 interspaces between the lesser calyces in the renal sinus are occup; by the branches of the renal bloodvessels and by fat.

Structure of the Ureter. —The ureter is a thick-walled muscu tube, lined with mucous membrane, and consists of three coats external or fibrous, middle or muscular, and internal or muco’


Middle Circular Muscular Fibres


Outer Longitudinal Muscular Fibres


53 1 • Transverse Section of the Lower Part of the Ureter, showing its Minute Structure.


The fibrous coat is composed of fibrous tissue, very compactly arrange^ and contains the bloodvessels and nerves, which here subdivide. Tl muscular coat is composed of plain muscular tissue, which is dispose in three layers —outer longitudinal, middle circular, and internal long tudinal. The outer longitudinal layer is best marked in the lower ha of the ureter, where it forms a continuous investment. In the uppf half of the tube its bundles are somewhat scattered. The mucoi coat superiorly is continued over the papillae of the renal pyramids, an interiorly becomes continuous with the mucous membrane of tb bladder. It is covered by stratified transitional epithelium, the celbeing arranged in four layers. In the most superficial layer (nearer the lumen of the tube) the cells are cubical, and present depressions o








THE ABDOMEN


909


eir deep surfaces, which receive the round ends of the pyriform cells the layer beneath. In the second layer the cells are pyriform, the und superficial ends being capped by the cubical cells of the first ^er, and the narrow deep ends projecting between the deeper cells, the third and fourth layers the cells are round or oval. The mucous smbrane is thrown into longitudinal folds, and the lumen of the be, which is of small size, presents under the microscope a branched •pearance on cross-section.

Around the lower end of the ureter for a distance of 3 or 4 mm. a fibrous-tissue covering known as Waldeyer’s sheath. Between is sheath and the ureteral wall proper is some loose bursal tissue, lich serves to facilitate the slight but important movement which kes place between the lower end of the ureter and the vesical wall contraction and relaxation of the bladder, and which has for its irpose the prevention of regurgitation of urine.

Blood-supply—Arteries. —The ureter receives branches from the nal, testicular (ovarian in the female), common iliac, and superior

sical arteries. The veins terminate in the vessels corresponding to these arteries. Lymphatics. —These pass to the juxta-aortic group of lumbar glands , Ld to the internal iliac glands.

Nerves. —These accompany the arteries, and are derived from e renal, testicular (ovarian in the female), and pelvic plexuses. The )res form plexuses in the fibrous and muscular coats, which contain lall ganglia.

Structure of the Pelvis and Calyces. —The structure of these parts the excretory apparatus resembles that of the ureter, with the

ception that they have only two layers of plain muscular tissue, stead of three as in the ureter. The layer which is wanting is the tier longitudinal layer. The lesser calyces are attached to the bases the papillae, and in these situations their fibrous coats become coniuous with that part of the fibrous capsule of the kidney which is 'olonged inwards through the hilum to line the sinus. The internal ngitudinal muscular fibres disappear towards the papilla, but the rcular muscular fibres accompany a lesser calyx to its termination, here they are arranged in the form of a circular band, which surrounds base of a papilla at the line of attachment of a calyx. The stratified ansitional epithelium of the mucous coat of a lesser calyx is pronged over the apex of each papilla.

Stroma of the Kidneys. —Between the uriniferous tubules and oodvessels there is a certain amount of connective tissue, which present in greatest abundance in the region of the papillary zones, his constitutes what is known as the fibrous or intestinal stroma, which there is a very small amount.

Early Condition of the Kidneys. —The kidneys of a child at the period of birth e lobulated, each lobule representing a renal pyramid surrounded by cortical bstance. In this respect they resemble the permanently lobulated kidneys of rtain animals— e.g., the ox. The lobules first become apparent towards the



9io


A MANUAL OF ANATOMY


end of the third month of intra-uterine life, and all traces of them have usi


disappeared by the eighth or tenth year.


Fig. 532. —-Kidney of a Child shortly before Birth.


They may, however, remain persh to a greater or less extent throug life, though this condition is of rare occurrence. It is, however, uncommon to find the surface o adult kidney marked by faint gro indicative of its original lobul condition. The disappearance of lobulated condition is brought a’ by the adjacent lobules coalescing, being accompanied by an incre development of cortical substanc the surface. The portions of cor substance which remain in the sp between the renal pyramids (ex their apical parts) form the r columns.


Development of the Kidney and Ureter.

The metanephros, or permanent kidney, is the last of the serie: excretory organs formed in the human embryo. For the acco of these organs, see p. 94 et seq.

The ureteric bud, the earliest formation in association with metanephros, begins to grow from the mesonephric duct when embryo is about 5 mm. long. It is a club-shaped, hollow outgrow which (Fig. 533) is surmounted from an early stage by a blastemal c formed by metanephric mesoderm. The markedly condensed d or inner layer of this cap is a very noticeable feature. The hoi outgrowth elongates fairly rapidly, growing in a cranial directi dorsal to the mesonephros, and carrying its blastemal cap on extremity as it grows. The bulbous end soon divides into two, c from these secondary outgrowths take place, each process carrying own blastemal cap upon it. In this way the cavities of the gret and lesser calyces are marked out. The process continues of elongat of outgrowth, subdivision, and consequent new outgrowths, and so and thus the collecting tubes of the kidney are made, each advanc end being covered by its metanephric cap of blastemal tissue.

At a later stage the earliest formed generations of these collecting-t systems are taken up into the calyces, so that the final number of collecting tu is not the same as the whole number formed, and more tubes come to open i the calyces directly than originally grew from them.

the formation of outgrowths goes on during the second, thi and fourth months, and probably for a considerable time after tl About the beginning of the third month, however, some of the tul subdivisions have reached their terminal stages, and the blasten caps of these terminal outgrowths begin to show activities whi ultimately lead to the formation of the secretory parts of the tubi system. 1 he inner zone of the cap forms a solid mass of cells, whi


THE ABDOMEN


911

>n becomes hollow, and is termed the renal vesicle. A curved short mle grows from this towards the bent end of the terminal collecting >e, with which it becomes connected. The renal vesicle is in the antime invaginated, and thus constitutes a glomerulus. The short ■ved tubule, somewhat in the shape of an S, elongates slowly. The


Fig. 533. —Schematic Drawings to illustrate the Formation of the Tubular System of the Kidneys.

A the ureteric outgrowth is shown arising from the mesonephric duct close to where this enters the cloaca. The enlarged end of the bud is covered by its blastemal cap. The enlarged end becomes bilobed. B, each lobe covered by its cap. Further subdivisions are seen in C. Terminal subdivisions are shown in D, where the cap is forming, on the left, a rounded ‘ renal vesicle/ R.V. On the right a tubule is growing from the vesicle toward the end of the collecting terminal. In E and F the tubule has fused with the terminal, and by elongating is making convoluted tubules and a loop of Henle. A vascular loop V grows against the renal vesicle and the adjoining part of its tubule, and invaginates them, producing a glomerulus.

'ond convoluted tubule is formed from the upper limb of the curve, s first convoluted tubule from its lower limb, and the intervening rtion is lengthened into Henle’s loop. Henle’s loops can be disL °tly recognized during the fourth month. The other descriptive rts of the system of tubules are gradually formed as elongation pn> isses.







912


A MANUAL OF ANATOMY


It is seen, then, that the tubule system, from the glomerulus to i arched collecting duct, is derived from the metanephric mesodei while the whole system of collecting ducts is formed by outgrov from the original ureteric growth. The junction between the t parts of the whole tubule system is effected shortly after the blaster tubule begins its growth; it is the failure of this junction which ir lead to one of the varieties of congenital cystic kidney.

The secondary junction between outgrowths from the mesonephric duct on one hand, and tubules formed separately in the mesoderm on the other ha is not in itself an extraordinary or out-of-the-way occurrence. It is well knc to occur in several species of animals, and it is apparently represented in development of the secondary tubules of the human mesonephros, which, wl


Suprarenal Glands


Fig. 534. —The Mesonephro, Mesonephric, and Para-mesonephric Due

and Contiguous Parts (Allen Thomson).

they are formed, extend toward the mesonephric duct, and meet secondary p jections from this duct in their direction. In the case of the metanephros t may, in the light of what has just been said, be looked on as corresponding w these secondary tubules of the mesonephros coming into relation with enormou elongated outgrowths from the mesonephric duct.

The vascular constituents, the interstitial connective-tissue stroma, renal columns, and the renal capsule are developed from the metanephric blaster

The ureter of either side, which originally opens into the uro-genital sii in common with the mesonephric duct, becomes detached from that duct a opens by an independent orifice into the uro-genital sinus on its dorsal aspe It may here be stated that the urinary bladder is developed from the u genital sinus.

Summary. —The pronephros is functional in lower vertebrates— e.g., cert; Fishes, and Amphibia during the larval stage. In Man it is rudimentary, d pronephric duct persists as the mesonephric duct.




THE ABDOMEN


913


Pronephros'


Diaphragmatic - Ligament of Pri/nit/t/e /t/cfney


Mesoneph . ' M( sorter hr Duct


Duct of Epoophoron


Prostatic

Utricle


6/rooep/fai S/pus fi/est/pp/e)


535 -—Development of the Uro-genital System (after Heisle).


58
















914


A MANUAL OF ANATOMY


The mesonephros or Wolffian body succeeds to the pronephros, and pe as the functional kidney in Fishes and Amphibia. In Man it atrophies large extent, and is replaced by the metanephros.

The metanephros is the permanent human kidney.

THE PELVIS.

The pelvis is the lower division of the abdomen which lies b the level of the pectineal lines and sacral promontory. Unlike abdomen proper, the walls of the pelvis are chiefly osseous, posterior wall is constructed by the sacrum and coccyx, with the ori of the pyrif ormes muscles. Each lateral wall is formed by the body spine of the ischium, and is covered by the obturator internus mu


Pelvic Colon Gt. Omentum


Fig. 536. —Transverse Section at Level of Lumbo-sacral Junction

(after Symington).


The anterior wall is formed by the bodies of the pubic bones, whicJ the median line construct the symphysis pubis. Between the poste: wall and each lateral wall is a large space, which is partly closed by powerful sacro-tuberous and sacro-spinous ligaments. This spact divided into two parts by the sacro-spinous ligament and the spin( the ischium. The upper part forms the greater sciatic foramen, wb transmits the pyrif ormis muscle; the superior gluteal vessels, lymphat and nerves; the inferior gluteal vessels, lymphatics, sciatic nerve, < posterior cutaneous nerve of thigh; the internal pudendal vessels c lymphatics and pudendal nerve; the nerve to the obturator inter] and gemellus superior; and the nerve to the quadratus femoris c gemellus inferior. The lower part forms the lesser sciatic foram which transmits the obturator internus muscle and its nerve, 1













THE ABDOMEN


915

rnal pudendal vessels, and the pudendal nerve. At each lateral t of the anterior wall is the obturator foramen, which is closed, -pt superiorly, by the obturator membrane, covered by the obturator rnus muscle. Below the symphysis pubis is the pubic arch, which •ccupied by the perineal membrane. The pelvic wall, thus conicted, is clothed by the pelvic fascia. Superiorly the pelvic cavity uite open and in free communication with the abdomen proper, jrioily it is for the most part closed, a complex septum separating rom the perineum underneath. This septum is partly muscular partly fascial. The muscles entering into it are the levatores ani the coccygei, which construct the pelvic diaphragm. The fascial rent is formed on either side by the visceral pelvic fascia, which hes the superior or pelvic surface of the muscular diaphragm, and the anal fascia, which covers its inferior or perineal surface. The


Fig. 537. —Male Pelvic Region seen from Above.


r of the pelvis is consequently movable, being capable of ascending descending. It affords passage to the rectum and urethra, and, in ition, in the female to the vagina.

Contents of the Pelvis. —The contents of the male pelvis are as

)ws: the pelvic colon and rectum; the bladder, with the lower tions of the ureters and the prostate gland, the latter containing prostatic part of the urethra; the seminal vesicles and the lower tions of the vasa deferentia; the internal iliac vessels and their fiches; portions of the superior rectal and median sacral vessels; rectal, vesical, and prostatic venous plexuses, the latter receiving dorsal vein of the penis in two divisions; the sacral and coccygeal uises and their branches; the pelvic portions of the gangliated ip a thetic trunks; and the obturator nerves in part of their course. The differences in the contents of the female pelvis, as compared h those of the male, are as follows:





A MANUAL OF ANATOMY


916

For the prostate gland and prostatic portion of the urethra sul tute the female urethra, uterus, and vagina. For the seminal vesi and portions of the vasa deferentia substitute the broad ligament the uterus and their contents—namely, the uterine tubes, the ova with their ligaments, and the ligamenta teres of the uterus. Ad< portions of the superior rectal and median sacral vessels portions of ovarian vessels. For the prostatic venous plexus substitute the pu< dal plexus, and add the uterine and ovarian venous plexuses.


THE MALE PELVIS.


General Position of the Viscera. —The pelvic colon and reel are situated upon the posterior wall, the pelvic colon reaching as lo\ the third sacral vertebra, and the rectum extending thence downwa


Comm. Iliac a. 1 ** 11 **** 1

Ureter- •

Lumbo-sacral Trunk Ext. Iliac A.


Obtur. N

Sup. Ves. A

Obtur. A

Vas Def Lat. Umbil. Lig.



Fig. 538. —Structures on Side Wall of Male Pelvis.


and forwards to the interval between the levatores ani muscles, wh< it is succeeded by the anal canal. The bladder is anterior in positi< being situated behind the bodies of the pubic bones, and resting by base upon the rectum. The seminal vesicles and the lower portions




THE ABDOMEN


917


vasa deferentia lie in contact with the base of the bladder, between nd the rectum. The prostate gland surrounds the prostatic part he urethra.

Peritoneum. —The disposition of the peritoneum will be simplified iefining the limits of the pelvic colon and rectum, and the different ts of the bladder. The pelvic colon extends from the inner border he left psoas major, just anterior to the left sacro-iliac articulation, he level of the third sacral vertebra. The rectum extends from the d sacral vertebra to a point t\ inches in front of and below the tip he coccyx, where it pierces the pelvic diaphragm to terminate in anal canal, which is the part of the large gut surrounded by the incter muscles. The bladder, when empty, presents the following ts: (1) an apex, which is directed forwards, and lies behind the upper


Pelvic Colon

i

/

Line of Peritoneal Reflection Ureter

t- Vas Deferens

Seminal Vesicle Bladder

/ Urachus


Symphysis Pubis


Levator Ani (cut) /


Anus


Corpus Cavernosum , Corpus Spongiosum Bulb and Bulbo-spongiosus ' Deep Layer of Sup. Perineal Fascia » Perineal Pouch Membranous Urethra Bulbo-urethral Gland Prostate Gland and Capsule


Perineal Membrane


Fig. 539.— The Viscera of the Male Pelvis (Lateral View).


of the symphysis pubis, where it has connected with it the median rilical ligament lepresenting the urachus; (2) a fundus (base) or terior surface, directed backwards and downwards towards the ■um, from which it is separated by the seminal vesicles and vasa irentia; and (3) a body which has a superior and two infero-lateral aces. Four borders are described, two being lateral, and serving separate the superior and infero-lateral surfaces; one posterior, mating the fundus from the superior surface, and stretching between two ureters as they pierce the bladder wall; and one faintly marked mior border, which separates the two infero-lateral surfaces. The

er enters the bladder at the junction of the fundus with the superior infero-lateral surfaces at what is known as the lateral angle.

The peritoneum, having descended from the posterior wall of the omen over the common iliac vessels, enters the back part of the








918


A MANUAL OF ANATOMY


pelvic cavity, where it invests the pelvic colon, forming behind il expanded, wavy mesentery, called the pelvic meso-colon, which attac it to the front of the sacrum as low as the third sacral vertebra. ' peritoneum is then prolonged upon the rectum, the upper third of wl it covers anteriorly and laterally , but not posteriorly, the middle t! being covered by it only anteriorly , whilst the lower third is destil of peritoneal covering. The point at which the peritoneum leaves rectum is fully 3 inches above the anus. The membrane is now can forwards to the upper ends of the seminal vesicles and the adjac portions of the vasa deferentia, which it covers. It then pa: forwards over the superior surface of the bladder, which it comple


Pelvic Colon Bladder


Fig. 540. —Transverse Section through the Second Sacral Vertebr

(after Symington).


covers as far as the apex. Here it meets the median umbilical ligame and by this is conducted from the bladder to the posterior surface the anterior abdominal wall. Along each lateral border of the blad< the peritoneum is reflected over the corresponding lateral wall of 1 pelvis. In passing from the rectum to the upper part of the base the bladder the peritoneum forms the recto-vesical pouch. The both of this pouch is, as a rule, fully 1 inch distant from the base of 1 prostate gland, thus leaving the part of the base of the bladder, cat the external trigone, quite free from peritoneum. The peritoneum, it passes to and from the bladder, forms certain folds, which constiti the false ligaments of the viscus. These are five in number as follow












THE ABDOMEN


919


posterior , which represent the laterally-disposed lips of the mouth

he recto-vesical pouch; two lateral, right and left, which represent reflection of peritoneum from each lateral border of the bladder the corresponding lateral wall of the pelvis; and superior, which he reflection of the peritoneum from the apex of the bladder to posterior surface of the anterior abdominal wall along the median bilical ligament. The parts of the bladder which are left uncovered peritoneum are (1) the inferior surface, and (2) the external trigone.

The pelvic peritoneum on either side of the bladder and rectum presents recesses when these viscera are moderately distended, which are named, a before backwards, paravesical and pararectal.

Retro-pubic Cellular Tissue. —This is a collection of areolar and pose tissues which lies between the posterior aspect of the bodies

he pubic bones, the bladder, and medial pubo-prostatic ligaments. Pelvic Fascia. —This fascia clothes the inner wall of the pelvis, and lishes inward expansions, which have an intricate connection with,


Parietal Pelvic Fascia

Visceral Pelvic Fascia Levator Ani Anal Fascia Obturator Internus Parietal Pelvic Fascia


i | v —*

Prostate Gland, with Urethra Pudendal Canal..

Fig. 541.—The Pelvic Fascia (Anterior View).

1 serve to support, the contained viscera. It is divisible into two 'tions—parietal and visceral.

Parietal Portion .—Over the posterior wall of the pelvic cavity

parietal portion of the pelvic fascia, which is here very thin, covers 1 intrapelvic portion of each pyriformis muscle and the corresponding ral plexus, this portion being known as the fascia of the pyriformis. er the lateral wall the fascia attains considerable strength, and is ached superiorly to the back part of the iliac portion of the pectineal 3 for a short distance, where it becomes continuous with the iliac cia. In front of this the fascia falls short of the pectineal line, and ixed to the lateral wall of the pelvis a little below the line, its attachnt being oblique, and accurately following the upper border of the turator internus muscle. When it arrives at the upper part of the turator foramen there is a break in the osseous attachment of the cia, which here joins the upper border of the obturator membrane sr the upper border of the obturator internus, and so converts the turator groove into a canal for the passage of the obturator vessels






920


A MANUAL OF ANATOMY


and nerve. At the upper and inner part of the obturator foramen fascia resumes its osseous attachment, but falls more and more st of the pelvic margin, its connection with the back of the body of os pubis being in a direction downwards and inwards till it reac a point just below the lower part of the symphysis pubis. The fas descends from the foregoing line of attachment, closely covering obturator internus, to be attached as follows from before backwar (i) to the pelvic aspect of the ischio-pubic ramus near the pubic ar medial to the obturator internus; (2) to the inner margin of the falcifc process of the sacro-tuberous ligament at the lower part of the iscl ramus, and also to the sacro-tuberous ligament itself, where thai attached to the inner margin of the ischial tuberosity; and (3) t< portion of the sacro-tuberous ligament near its ischial attachment, e to the anterior margin of the greater sciatic notch The lateral port of the parietal pelvic fascia, from its relation to the obturator inten


Parietal Pelvic Fascia


Levator Ani..

Anal Fascia

Obturator Internus..-N$!/ Parietal Pelvic Fascia-

Pudendal Canal


Visceral Pelvic Fascia


--- Seminal Vesicle


Vas Deferens


h J G. 542. —Diagram of the Pelvic Fascia from Behind.


muscle, is sometimes called the obturator fascia. From its lower attac ment the fascia is continued backwards and inwards over the great sciatic foramen, pyriformis, and sacral plexus to the sacrum, as t. fascia of the pyriformis. As it covers the foramen it is perforated 1 the superior and inferior gluteal, and internal pudendal vessels, and m consequence indistinct.

At the anterior part of the pelvic cavity the fascia, after takii attachment to the pelvic surface of the ischio-pubic ramus near t] pubic arch, is continued inwards over that arch, where it lies behii the sphincter urethrae muscle, and forms one half of the superior lay ot the perineal membrane, the other half being formed by the corr spondmg portion of the fascia of the opposite side. When it arrives ; the urethra it changes its course, and passes backwards over the anterii border of the levator ani to blend with that portion of the visceral pelv fascia which ensheathes the prostate gland.




THE ABDOMEN


921


In the direction of a line passing from the inner aspect of the ischial ine to the back of the body of the os pubis, near its lower end and close the symphysis, the lateral pelvic fascia is strengthened by fibres dch impart to it a white colour. This part is called the arcus tenleus [white line), and it serves to divide the fascia into two portions— per or pelvic proper, and lower or perineal. The pelvic portion )ks into the pelvic cavity, and covers the upper part of the obturator

ernus, whilst it is itself covered by the peritoneum. The perineal rtion covers the lower part of the obturator internus, and lies on the ter wall of the ischio-rectal fossa, where it constructs the pudendal rial. The under aspect of the arcus tendineus affords extensive [gin to the levator ani muscle.

Visceral Portion of the Pelvic Fascia. —The visceral portion is stined to support the lower part of the bladder, seminal vesicles, rminal portions of the vasa deferentia, prostate gland, and rectum, is a laminar offshoot of the parietal portion, from which it springs mg the arcus tendineus. Though, however, this is its principal urce, it has an independent origin anteriorly on either side of the ddle line from the posterior aspect of the body of the os pubis near e lower part of the symphysis. In this latter situation it lies a little ove the attachment of the parietal portion, the anterior fibres of the rator ani taking origin from the portion of bone between the two seise. Though the visceral portion forms one continuous sheet along pelvic attachment, its ultimate disposition is so intricate that it is nvenient to consider its arrangement under three divisions.

1. Opposite the bladder, seminal vesicle, and rectum. In this region e visceral portion of the fascia passes inwards as far as the outer rder of the seminal vesicle. In doing so it covers the upper surfaces of e levator ani and coccgyeus, and is in turn covered by the peritoneum.

the outer border of the seminal vesicle it divides into three laminae—'per, middle, and lower. The upper or vesical lamina ascends upon e lateral aspect of the bladder for a short distance, and ultimately >es itself in the muscular tissue of the vesical wall. This portion at ch side forms the lateral pubo-prostatic ligament of the bladder. The ddle or recto-vesical lamina passes inwards between the base of the idder and the rectum, and is continuous with the corresponding nina of the opposite side. As it passes inwards it furnishes a sheath the seminal vesicle and adjacent portion of the vas deferens, closely 'apping these structures to the base of the bladder. The lower or 3tal lamina descends upon the side of the rectum, and passes to its sterior surface, where it is continuous with the rectal lamina of the posite side.

2. Opposite the lateral aspect of the prostate gland. I11 this situa>n the visceral portion of the fascia also divides into three laminae upper, middle, and lower. The upper or prostatic lamina passes vards over the anterior surface of the prostate gland, and is congous with the prostatic lamina of the opposite side. The middle recto-prostatic lamina passes inwards between the posterior surface


922


A MANUAL OF ANATOMY


of the prostate gland and the rectum, and is continuous with corresponding lamina of the opposite side. The lower or rectal lam is unaltered in its disposition. The upper or prostatic and middle recto-prostatic laminse furnish a stout sheath to the prostate gland.

3. Between the pubic bodies and the anterior aspect of the pros gland. The portion of the visceral fascia in this region represe the upper lamina in the other regions, and may be called the pu prostatic lamina. It is arranged in the form of two stout cords, wb are known as the medial pubo-prostatic ligaments or the anterior i ligaments of the bladder. Each is attached anteriorly to the poste] aspect of the body of the os pubis, near the lower part of the symphy and a little above the attachment of the parietal portion of the pe] fascia in this region, the anterior fibres of the levator ani taking ori from the portion of bone between the two fasciae. As the cord -1 fascial bands pass backwards they are connected by a portion of visceral fascia which covers the dorsal vein of the penis and lies deef thus giving rise to a small pouch, which is capable of admitting ■ point of a finger. This pouch is filled with fat, which is continuous w the retro-pubic pad of fat. The anterior portion of the visceral fas lies upon the anterior surface of the prostate gland, and on reach the bladder it passes forwards on its inferior surface, where it sc disappears in the muscular tissue of the vesical wall. The mec pubo-prostatic ligaments are largely composed of plain muscular tiss which is derived from the longitudinal fibres on the inferior surface the bladder as they pass to take attachment to the back of the bod of the pubic bones on either side of the middle line. These fib constitute the so-called pubo-vesical muscles.

Anal Fascia. —This very thin sheet of fascia is an offshoot fr< the parietal pelvic fascia just below the white line and the origin the levator ani. It closely covers the ischio-rectal surface of tl muscle and of the coccygeus, upon which it descends to the region the anus, where it blends with the aponeurotic investment of t sphincter ani externus.

Sympathetic Plexuses in the Pelvis. —These are derived from t hypogastric plexus, which is formed by the fusion of the two latei strands of the aortic plexus after they have crossed the common ili arteries. It is reinforced by branches from the ganglia of the lumb sympathetic trunks, and is situated in front of the body of the fif lumbar vertebra between the common iliac vessels. It is a lar£ flattened plexus, measuring about ij inches in breadth, and breaks 1 into two divisions, which form the right and left pelvic plexuses. Ea< of these enters the pelvis on the inner side of the internal iliac arte and takes up a position on the side of the rectum. The pelvic plexi of each side is reinforced by branches from the upper one or two gangl of the pelvic sympathetic trunk, and by spinal fibres from the anter! primary divisions of the third and fourth sacral nerves (sometimes at the second), there being very small ganglia at the places of junctio From each plexus the following secondary plexuses are given off, whic


THE ABDOMEN


923


xompany the corresponding branches of the internal iliac artery: aemorrhoidal, vesical, and prostatic, the latter being replaced in the male by the vaginal and uterine plexuses.

Internal Iliac Artery. —This vessel arises from the common iliac Dposite the sacro-iliac joint at the level of the lumbo-sacral joint, id terminates opposite the upper border of the greater sciatic notch y.dividing into an anterior and a posterior division. The length of le vessel is about ij inches, and its direction is downwards and ickwards.

Relations — Anterior. —The artery is covered by the peritoneum, id the ureter descends over it. In front of the ureter are the ovary id the fimbriated extremity of the uterine tube. The terminal part i the ileum forms an anterior relation of the right vessel, whilst the dvic colon is similarly related to the left. Posterior. —The vessel ‘sts chiefly upon its own vein, but near its origin it is placed over the )mmencement of the common iliac vein. Behind the veins there are le lumbo-sacral trunk and sacro-iliac joint. Lateral. —The psoas tajor, with the intervention of the external iliac vein, and subsequently le lateral wall of the pelvis, with the intervention of the obturator srve. Medial. —The peritoneum.

Varieties. —The chief variety affects the length of the vessel. It may be lorter or longer than usual, according as the common iliac is longer or shorter lan normal, or according to the height at which the internal iliac ends in its vo divisions.

Foetal Condition. —During foetal life the internal iliac is represented by the mbilical artery, the size of which greatly exceeds that of the external iliac. The mction of this artery is to carry the impure blood from the foetus to the placenta

the mother. The umbilical artery passes forwards to the posterior surface of le anterior wall of the abdomen, being crossed by the vas deferens. It then scends to the lower part of the umbilicus, where it leaves the abdomen with its llow. The two umbilical arteries, together with the umbilical vein, form the mbilical cord, in which the arteries describe spiral coils around the vein. The •teries convey the impure blood to the placenta, where it is purified, after which is returned to the abdomen of the foetus by the umbilical vein. After birth, lere being no further use for the placental circulation, the umbilical cord is tied, id the child separated from the mother. The umbilical arteries become imperious, and each is converted into a fibrous cord. The obliteration, however, does it involve the first i-J inches of the vessel, which persists as the internal iliac rtery of the adult. Moreover, the proximal end of the fibrous cord representing ie obliterated umbilical remains pervious also, and being connected with the iterior division of the internal iliac, it furnishes the superior vesical artery or "teries. This pervious portion lies along the side of the pelvis beneath the eritoneum, where it is crossed by the vas deferens in the male and the ligatentum teres of the uterus in the female. The foetal umbilical artery gives off ie inferior gluteal, which is the primitive main artery of the lower limb, until ie external iliac, which becomes the femoral, is developed.

Branches.—These are subject to much variation. In normal ases they arise from the two terminal divisions, anterior and posterior, xne of them being parietal in their distribution, which will be indicated y the letter P, whilst others are visceral, which will be indicated by he letter V. The branches are as follows:


924


A MANUAL OF ANATOMY


Anterior Division.


Visceral.

Umbilical (which gives off superior vesical). Inferior vesical.

Middle rectal.


Parietal.

Obturator.

Internal pudendal. Inferior gluteal.


Posterior Division

Parietal.

Uio-lumbar. Lateral sacral. Superior gluteal.


In the female the inferior vesical artery may be replaced by t vaginal, or the vaginal may be an independent branch; the uteri artery is always a special branch.


Lateral J Sacral \


„■ Left Common Iliac


Anterior Superioi Iliac Spine

Internal Iliac

_- Ilio-lumbar

_Posterior Division

_External Iliac

Anterior Division


c • rrp

Superior Gluteal

Inferior Gluteal


Sacro-spinous ^

Ligament A

Sacro-tuberous'

Ligament

Internal Pudendal'

Inferior Rectal


Umbilical - - - ' Inferior Vesical Deep Circumflex Iliac Inferior Epigastric

....Obturator Nerve

-Obturator Artery

Obturator Vein

.Obturator Membrane

....Symphysis Pubis


Superficial Perineal ‘

Transverse Perineal


Dorsal Artery of Penis Deep Artery of Penis

Artery of the Bulb


^ IG - 543 -—The Left Internal Iliac Artery and its Branches.


Anterior Division. — 1 he superior vesical artery (V) arises from th pervious portion of the fibrous cord which represents the fcetal umbilica artery, and at once breaks up into several twigs which frequently hav independent origins. They are distributed to the upper portion of th bladder, and anastomose with the vesical of the obturator, and th mfeiior vesical of the same side, and with the superior vesical of th opposite side. The superior vesical furnishes the following branches urachal to the medial umbilical ligament; ureteric to the lower end c









THE ABDOMEN


925


L e ureter; and deferential (as a rule) to the vas deferens, though this •anch may arise from the inferior vesical. The artery to the vas deferens, tiich is usually of small size, divides into a descending and an ascendg branch. The descending branch passes downwards to supply the npulla of the vas deferens and the seminal vesicle. The ascending ■anch accompanies the vas deferens through the deep inguinal ring id inguinal canal into the scrotum, supplying the vas deferens, and ving a few twigs to the tail of the epididymis, in which latter situation anastomoses with the epididymal branch of the testicular artery, i the spermatic cord it also anastomoses with the cremasteric branch the inferior epigastric. The artery to the vas is sometimes of large ze, and then takes the place of the testicular artery if that vessel Lould be absent. One of the branches of the superior vesical artery is unetimes spoken of as the middle vesical.

The inferior vesical artery (V) takes an inward course to the lower )rtion of the bladder, which it supplies, giving branches to the seminal isicle, ampulla of the vas deferens, and prostate gland, and in the male to the vagina. It sometimes gives off the artery to the vas derens, and it may give origin to an accessory pudendal. It anastooses with the superior vesical and middle rectal of its own side, and ith its fellow of the opposite side.

The middle rectal artery (middle hsemorrhoidal artery) (V) often 'ises in common with the inferior vesical. It is distributed to the ctum, and gives branches to the seminal vesicle, ampulla of the vas derens, and prostate gland. The anastomoses which it establishes 'e with the superior rectal of the inferior mesenteric, the inferior

ctal of the internal pudendal, the inferior vesical of its own side, and s fellow of the opposite side.

The obturator artery (P) passes along the outer wall of the pelvic ivity on its way to the obturator canal, lying between the parietal dvic fascia and the peritoneum. It has the obturator nerve above , and its own vein below it. In entering the obturator canal, by which emerges from the pelvis, the artery does not pierce the parietal pelvic

scia, but passes over its upper border, where that joins the upper part • the obturator membrane. As the artery passes along the pelvic wall furnishes the following branches: muscular to the obturator internus ; iac to the iliac fossa, which supplies the bone, psoas major, and iliacus, id anastomoses with the iliac branch of the ilio-lumbar; vesical, which caches the side of the bladder within the lateral false ligament; and ubic to the back of the body of the os pubis, where it anastomoses with ie pubic branch of the inferior epigastric from the external iliac, and s fellow of the opposite side.

For the distribution of the obturator artery outside the pelvis, P- 589 The obturator artery sometimes arises from the inferior epigastric iee P. 566).

The internal pudendal artery (internal pudic artery) (P) is one of

ie terminal branches of the anterior division. It descends with the


926


A MANUAL OF ANATOMY


inferior gluteal artery upon the pyriforrnis and sacral nerves, a emerges from the pelvis through the lower compartment of the grea sciatic foramen, having previously pierced the parietal pelvic fas( The intrapelvic branches of the vessel are unimportant, and are c tributed to the pyriforrnis, coccygeus, obturator internus, and pel fascia. For the further course and distribution of the artery, see 1 gluteal region and the perineum, pp. 539 and 686.

The inferior gluteal artery (sciatic artery) (P) is the other and lap terminal branch of the anterior division. It descends, usually behi the internal pudendal, upon the pyriforrnis and sacral nerves, a emerges from the pelvis through the lower compartment of the grea sciatic foramen, having previously pierced the parietal pelvic fasc Within the pelvis the artery gives off branches to the pyriforrnis, levai ani, coccygeus, rectum, bladder, seminal vesicle, and prostate glar Although very variable in their origin and course, the inferior gluti artery as it runs backwards frequently passes between the anter: primary divisions of the first and second sacral nerves and the interi pudendal between those of the second and third sacral nerves.

For the extrapelvic course and distribution of the vessel, see p. 5'

Posterior Division. —The ilio-lumbar artery (P) passes upwards a: outwards in front of the sacro-iliac articulation, between the lurnt sacral trunk and obturator nerve. In its course it passes behind t external iliac, or, it may be, the common iliac, vessels, and also behi] the psoas major and iliacus. On reaching the back part of the ili fossa it divides into two branches, iliac and lumbar. The iliac brant passing transversely, ramifies in the iliacus and ilium, and anastomos with the iliac branch of the obturator and branches of the deep circui flex iliac from the external iliac. The lumbar branch ascends benea the psoas major on to the quadratus lumborum, where it anastomos with the terminal part of the deep circumflex iliac, and the last lumb of the abdominal aorta. In its course it furnishes a spinal branch, whi< enters the vertebral canal through the intervertebral foramen betwe^ the fifth lumbar and first sacral vertebrae, to be distributed in a mann similar to the other spinal arteries.

The lateral sacral arteries (P) are usually two in number, superi and inferior. They course downwards and inwards to the front the lateral mass of the sacrum, passing in front of the pyriforrnis ar sacral nerves. Upon the sacrum both arteries lie lateral to the anterf sacral foramina, the superior being confined to the region of the fir two foramina, whilst the inferior descends as low as the coccyx, whe: it anastomoses with the median sacral artery. They are distributf to the pyriforrnis and sacral nerves, and furnish spinal branches, whic enter the anterior sacral foramina, and so reach the sacral canal, whe] they supply its contents. Each spinal branch, before entering tl sacral canal, gives off a posterior branch, which emerges through tl posterior sacral foramen, and anastomoses with branches of the superk and inferior gluteal and internal pudendal. The lateral sacral arterk anastomose with each other and with the median sacral.


THE ABDOMEN


927


The superior gluteal artery (P) is a large vessel, which is the connation of the posterior division. It is destined for the supply of the iteal region, and lies within the pelvis for a very short distance. Its ■ection is backwards through the parietal pelvic fascia, and between 3 lumbo-sacral trunk and the anterior primary division of the first

ral nerve, its escape from the pelvis being through the upper comrtment of the greater sciatic fordfaten. The branches of the artery thin the pelvis are unimportant.

For the extrapelvic course and distribution of the vessel, see p. 536. The branches of the internal iliac, with one exception, have to irce the pelvic fascia. The exception is the obturator artery, which, stated, passes over the upper border of the parietal pelvic fascia at e obturator canal.

Internal Iliac Vein. —This vessel results from the union of tributaries lich correspond, for the most part, with branches of the internal ic artery. The ilio-lumbar vein, however, is an exception, inasmuch it is a tributary of the common iliac vein. Moreover, during foetal 3 the umbilical vein, which corresponds to the umbilical artery, passes the liver after entering the abdomen of the foetus. The internal iliac in extends from the upper part of the greater sciatic notch to the

ro-iliac articulation on a level with the pelvic brim, where it joins e external iliac, and so the common iliac vein is formed. In its course lies behind the corresponding artery. There are no valves in the vein elf, but its branches are freely provided with them.

The internal iliac vein is developed from the lower part of the cardinal in.

Internal Iliac Lymphatic Glands. —These glands are about ten in mber, and are associated with the origins of the branches of the ternal iliac artery. They are arranged in a curve, which usually gins in front in a gland situated between the obliterated umbilical d obturator arteries, and then is formed in succession by uterine prostatic, inferior gluteal and internal pudendal, middle rectal, perior gluteal and sacral glands. They are situated immediately ider the peritoneum, between it and the parietal layer of pelvic fascia, though occasionally some of them may be formed lateral to this scia.

The afferent vessels of the internal iliac glands return lymph from e parts supplied by the branches of the internal iliac artery. Thus, ey receive afferent vessels from the following parts:

1. The anal canal, but not the anal margin.

2. Lower part of the rectum.

3- Bladder.

4- Seminal vesicle and vas deferens.

5 - Prostate gland.

6. Prostatic, membranous, and bulbar portions of the urethra, part.

7 - Uterus (cervix).

8. Vagina.


928


A MANUAL OF ANATOMY


9. Deep structures of gluteal region, supplied by superior glu artery.

10. Deep structures of upper part of back of thigh, supplied inferior gluteal artery.

11. Obturator region.

12. Deep structures of perineum.

The efferent vessels of the internal iliac glands pass to the mic group of common iliac glands.

Anterior Primary Divisions of the Sacral and Coccygeal Ner

—There are five sacral nerves and one coccygeal nerve on either s The anterior primary divisions of the first four sacral nerves enter

pelvis through the anterior sa< foramina, and that of the fifth sa< passes between the inferior lab angle of the sacrum and the trt verse process of the first coc geal vertebra, through the coccyg muscle. The anterior primary d sion of the coccygeal nerve enl the pelvis below the transverse j: cess of the first coccygeal verte through the coccygeus muscle. ' first and second sacral nerves of large size, and their course obliquely downwards and outwai Beyond the second they dimin rapidly in size, and pass more h< zontally. They receive grey rz communicantes from the adjao ganglia of the pelvic sympathy trunk, and the third and fou] nerves (sometimes also the secoi furnish white rami communican to the corresponding pelvic plex The anterior primary divisions of 1 first and second sacral nerves divi each into an anterior or ventral and a posterior or dorsal bran< dhe anterior primary division of the third sacral nerve divides ir an upper and a lower branch and is known as the nervus bigemin\ The anterior primary division of the fourth sacral nerve also divic into an upper and a lower branch, and it is known as a nervus furcal The lumbo-sacral trunk in two divisions, ventral and dorsal, the anted primary divisions c>f the first two sacral nerves, the upper and low branches of the third sacral, and the small upper branch of the four sacral form the sacral plexus, whilst the large lower branch of the four sacral, the fifth sacral, and the coccygeal form the coccygeal plexus.

Sacral Plexus. —This plexus, formed as stated, is a large flatten mass, lying upon the pyriformis muscle, and behind the parietal pel\



Fig. 544.— Plan of Position of Structures lying on the Front of the Sacrum.

LSA, lateral sacral arteries; MSA, middle sacral arteries; C, coccygeal ganglion ; SS lig., sacrospinous ligament.




THE ABDOMEN


929


cia, which separates it from the inferior gluteal and pudendal vessels. 3 mass ultimately forms two bands, upper and lower. The upper sciatic band, which is the larger of the two, receives the lumbo-sacral nk, first sacral, larger portion of the second sacral, and upper branch the third sacral nerves. It is flat and somewhat triangular, and is itinued into the sciatic nerve, whjch leaves the pelvis through the r er part of the greater sciatic foramen below the pyriformis without rcing the parietal pelvic fascia. The upper band and its contributory ves are sometimes spoken of as the sciatic plexus . The lower or

A


^ IG - 545-— A, The Sacral Plexus; B, The Sacro-Coccygeal Plexus.

A B

c > 1 , 1 . Nerve to Quadratus Femoris 4 .S. Fourth Sacral, giving a Branch to Sacral Plexus

l > 2 > 2 - Nerve to Obturator Internus V. Visceral Branches

b 3> 3- Posterior Cutaneous Nerve of Thigh M. Muscular Branches

T.C. Terminal Cutaneous Branches


endal band, the smaller of the two, receives fibres from the second er branch of the third, and upper branch of the fourth sacral nerves, ^ is continued into the pudendal nerve, which leaves the pelvis, like the tic, through the lower compartment of the greater sciatic foramen hout piercing the parietal pelvic fascia. The lower band and its tributory nerves are sometimes spoken of as the pudendal plexus. ' sciatic and pudendal nerves are thus the terminal branches of the r al plexus. The reason of the name nervus bigeminus, as applied to third sacral nerve, is because it enters into the sciatic band by its )er branch, and into the pudendal band by its lower branch.

59


930


A MANUAL OF ANATOMY


Branches. —The branches of the sacral plexus are arranged in groups—collateral and terminal.

Collateral Group. —The branches of this group form three sel visceral, muscular, and cutaneous.

Visceral Branches. —These are derived from the third sacral that part of the fourth which enters into the sacral plexus (someti: also from the second). They are white rami communicantes, wl reinforce the pelvic plexus of the sympathetic, a few of them b( traceable independently to the pelvic viscera. They are known as pelvic splanchnics.

Muscular Branches .—The superior gluteal nerve arises by< tl roots from the dorsal divisions of the descending branch of the for lumbar, fifth lumbar, and first sacral nerves. It passes outwards backwards, and leaves the pelvis with the superior gluteal artery thro the upper compartment of the greater sciatic foramen, to be distribr to the gluteus medius, gluteus minimus, and tensor fasciae latae muse The inferior gluteal nerve arises by three roots from the do divisions of the fifth lumbar and first and second sacral nerves, leaves the pelvis through the lower compartment of the greater sci foramen, below the pyriformis and dorsal to the sciatic nerve, to distributed to the gluteus maximus. It is usually intimately associa with the posterior cutaneous nerve of thigh.

The nerves to the pyriformis, which are usually two in numl spring from the dorsal divisions of the first and second sacral nerve The nerve to the obturator internus and gemellus superior ar by three roots from the ventral divisions of the fifth lumbar and t and second sacral nerves. It leaves the pelvis through the lo compartment of the greater sciatic foramen, crosses the back of ischial spine, where it lies lateral to the internal pudendal vessels, ; then passes through the lesser sciatic foramen to the outer wall of ischio-rectal fossa, where it enters the inner or pelvic surface of obturator internus. In the gluteal region it gives a branch to gemellus superior when that muscle is present.

The nerve to the quadratus femoris and gemellus inferior arises three roots from the ventral divisions of the descending brand] the fourth lumbar, fifth lumbar, and first sacral nerves. It leaves pelvis through the lower compartment of the greater sciatic foran and then lies between the ischium and the sciatic nerve. It s sequently descends over the back of the capsular ligament of the 1 joint, to which it usually gives a branch, and beneath the gemelli; obturator internus to the deep surface of the quadratus femoriSj which it ends, having previously given a branch of the gemellus infer Cutaneous Branches .—The posterior cutaneous nerve of thigh (sr sciatic nerve) arises by three roots from the posterior aspects of first, second, and third sacral nerves. It leaves the pelvis through lower compartment of the greater sciatic foramen, and is distribu to (i) the lower and outer part of the gluteal region by its glui cutaneous branches, (2) the skin of the scrotum by the long perir


THE ABDOMEN


93 i


rve, (3) the skin of the back of the thigh, and (4) the skin of the back the leg as low as about the centre of the calf.

The perforating cutaneous nerve arises by two roots from the sterior aspects of the second and third sacral nerves. It passes ckwards through the sacro-tuberous ligament, after which it turns and the lower border of the glutefis maximus near the coccyx to be stributed to the skin over the lower and inner part of that muscle. Terminal Group. —This group is comprised of two nerves—namely, e sciatic and the pudendal.

The sciatic nerve is the continuation of the upper or sciatic band of e sacral plexus. In reality it is made up of the two divisions in which ultimately ends—namely, the lateral and medial popliteal—which lie >se together within the same sheath. Sometimes, however, these two visions arise separately from the sacral plexus, in which cases the

eral popliteal nerve may pass through the pyriformis. Again, ough the sciatic nerve may be apparently single, a careful dissection it, after the removal of its sheath, will reveal the lateral and medial pliteal nerves, which can be shown to have independent origins. The

eral popliteal nerve derives its fibres from the dorsal divisions of the scending branch of the fourth lumbar, fifth lumbar, and first and

ond sacral nerves; and the medial popliteal nerve derives its fibres >m the ventral divisions of the foregoing nerves, and in addition from e upper branch of the third sacral.

The sciatic nerve leaves the pelvis through the lower compartment the greater sciatic foramen below the pyriformis.

The pudendal nerve (pudic nerve) is the continuation of the lower pudendal band of the sacral plexus. It arises by three roots from e ventral division of the second, the lower branch of the third, and e upper branch of the fourth sacral, the root from the third being e largest. The nerve leaves the pelvis through the lower compartsnt of the greater sciatic foramen, crosses the back of the ischial ine, where it lies medial to the internal pudendal vessels, passes rough the lesser sciatic foramen, and then traverses the outer wall of e ischio-rectal fossa. Having given off the inferior haemorrhoidal rve, it divides into the perineal and dorsal nerve of penis, which th the internal pudic vessels are contained in the pudendal canal.

The sacral plexus and its branches being situated behind the parietal fvic fascia, the branches do not pierce the fascia as they leave the Ivis. The branches of the internal iliac artery, on the other hand, ing placed in front of the parietal pelvic fascia, have to pierce it, th the single exception of the obturator artery.

Coccygeal Plexus. —The nerves which form the plexus are the wer branch of the anterior primary division of the fourth sacral, the terior primary division of the fifth sacral, and the anterior primary vision of the coccygeal nerve. The upper branch of the fourth sacral ters the pudendal band of the sacral plexus, and the fourth sacral therefore a nervus fur calls, inasmuch as it gives a branch to the sacral exus and one to the coccygeal plexus. Before entering the coccygeal


932


A MANUAL OF ANATOMY


plexus the lower branch of the fourth sacral nerves gives off visce: and muscular branches. The visceral branches for the most part re: force the pelvic plexus of the sympathetic as white rami commu: cantes, but a few of them pass independently to the pelvic visce: The muscular branches supply the levator ani, coccygeus, and sphincl ani externus. The branch to the latter muscle reaches the perinei either by piercing the coccygeus, or by passing between it and t levator ani, and besides supplying the external sphincter, it gi\ branches to the skin between the coccyx and the anus. The nerve known as the perineal branch of the fourth sacral. The lower bran of the fourth sacral nerve, having parted with the foregoing offse descends upon the coccygeus, where it joins the fifth sacral, which h just entered the pelvis through that muscle. The conjoined nerve n< descends, and is soon reinforced by the coccygeal nerve, which a] enters the pelvis by piercing the coccygeus. In this manner t coccygeal plexus is formed. It lies at the lower part of the posted wall of the pelvis upon the coccygeus, and the nervous loop takes downward course. Subsequently it divides into several twigs, whi leave the pelvis by piercing the coccygeus, the sacro-spinous ligamei and the adjacent portion of the gluteus maximus to be distributed the skin over the coccyx.

Ureters. —The ureter of each side, having crossed the terminati of the common iliac, or the commencement of the external iliac artei enters the pelvis. It then passes downwards, describing a curve wi its convexity backwards and outwards, lying in front of the interr iliac artery. It next runs along the outer wall of the pelvis, lyi: beneath the peritoneum, and crossing medially the obturator vess< and nerve, and the obliterated umbilical artery. It subsequent passes inwards to the bladder, being crossed medially by the vas deferer Haying arrived at the lateral or ureteric angle of the bladder, it pass obliquely through the vesical wall anterior to the upper free end of t seminal vesicle, being here about 2 inches distant from its fellow, ai about 1 \ inches from the base of the prostate gland.

Bladder. —The bladder, when empty, or only moderately d: tended, lies entirely within the cavity of the pelvis. When, howeve it is fully distended, the apical part of the viscus rises above the le\ of the symphysis pubis into the hypogastric region of the abdonn for at least 2 inches, and in cases of marked over-distension it may rea< to the umbilicus, or even higher. The bladder, therefore, has to 1 considered under two aspects—namely, when empty or only moderate distended, and when fully distended.

The bladder, when empty or moderately distended , is triangular, ai presents the following component parts: an apex, a base, and a bod the latter presenting a superior surface, two inferior lateral surface two lateral borders, a posterior border, an antero-median border, ai two lateral angles.

The apex is directed forwards, and lies behind the upper part of t] symphysis pubis. It has connected with it the median umbilic


THE ABDOMEN


933


lament representing the urachus , which ascends on the posterior rface of the anterior abdominal wall to the lower part of the umlicus. The base or fundus is directed backwards and downwards wards the rectum, from which it is separated by the seminal vesicles id terminal portions of the vasa deferentia, and the recto-vesical mina of the visceral portion of the pelvic fascia. The base is separated Dm the superior surface by the posterior border, and from each unded inferior lateral surface by a slight elevation, which extends Dm the lateral or ureteric angle of either side to the urethral opening, le superior surface is three-sided and slightly convex. It is usually lated to a few coils of the small intestine, and a loop or two of the lvic colon. The inferior lateral surfaces , which are convex, rest


d. 546.—Showing the Internal Trigone of the Bladder and the Relations of the Vas Deferens (DD), Ureter, etc., in its Neighbourhood.

'On (1) the symphysis pubis and the adjacent portions of the posterior rfaces of the bodies of the pubic bones, (2) the retro-pubic pad of “» ( 3 ) the medial pubo-prostatic ligaments, (4) the fasciae covering e u pper part of the obturator internus muscle and the upper surface the levator ani, and (5) the prostate gland. The lateral borders start )m the apex, whence they pass backwards in a diverging manner, and ch marks the separation between the superior surface and the correonding inferior lateral surface. Posteriorly each lateral border meets e posterior border. The posterior border extends transversely beeen the superior surface and the base. At either end it is joined by s lateral border. The lateral or ureteric angles are situated on either e at the junction of the lateral with the posterior border. At these gles the ureters pass through the vesical wall (Fig. 546). At its


934


A MANUAL OF ANATOMY


most dependent point the bladder is continuous with the uretl There is, however, no contraction of the bladder at or near this poi in other words, no neck.

The external trigone is the name given to a limited triangular sp upon the exterior of the base, which is bounded as follows: above, the bottom of the recto-vesical pouch of peritoneum; laterally, by ampulla of the vas deferens, lateral to which is the seminal vesic and below, by the approximation of the ejaculatory ducts at the b of the prostate gland. The length of the space from the apex be] to the base above is, as a rule, fully i inch, but its breadth is limi by the encroachment upon it of the ampullae of the vasa deferen There is no peritoneum over this region.

The Bladder during Distension and when fully distended. —As bladder becomes distended very little alteration takes place in a doi,

ward direction. The


Left Ureter


Line of

Reflection of-' Peritoneum


External Trigone


Ejaculatory Duct of Right Side


THE


marcations between i component parts of i viscus gradually disappe and it becomes ovoid. 1 apex appears above 1 symphysis pubis, and the organ increases in s the apex and the super portion of the body asce into the hypogastrium such a manner as to st: off the parietal peritonei from the back of the lin alba. In this way a p< tion of the original inferi lateral surface, devoid


Fig. 547. —Dissection of the Base of . . , , .

Bladder, showing the Seminal Vesicles, peritoneum, is brought in Vasa Deferentia, and External Trigone, direct contact with t

back of the linea all which is now also free from peritoneal covering. A distended bladd may therefore be punctured or opened through the linea alba abo the symphysis pubis without doing any injury to the peritoneui The bladder is now becoming spheroidal, and its long axis is direct downwards and backwards. The part which rises highest is not t original urachal apex, but that part of the superior surface which immediately adjacent to, and behind, the apex.

Peritoneal Relations. —The only part of the bladder which is coven by peritoneum is the superior surface. The peritoneum is reflect! from the apex along the urachus, and at either side it leaves the org; along the lateral border. When the bladder is distended the latei reflection of peritoneum appears to take place along the course of t; obliterated umbilical artery, but this is due to the lateral distensh and elevation of the viscus, the obliterated umbilical itself lying aloi





THE ABDOMEN


935


outer wall of the pelvis. For the structure and development of bladder, see pp. 949 and 955.

Vas Deferens in the Pelvis. —The vas deferens enters the abdomen )ugh the deep inguinal ring, where it lies on the inner side of the er constituents of the spermatic cord.- It then hooks round the er side of the inferior epigastric artery, and having crossed the ernal iliac vessels from without inwards, it dips down on the inner

of the external iliac vein. In this way it enters the pelvis under er of the peritoneum. It now passes backwards and downwards >n the lateral wall, crossing median to the obliterated umbilical ery, the ureter, and the obturator vessels and nerve. It is then

Symph. Pub.


Fig. 548. —Transverse Section through Last Piece of Sacrum

(after Symington).


ected inwards to the inner aspect of the upper end of the seminal side, whence it passes downwards, inwards, and forwards along the se of the bladder, where it lies close to the inner side of the seminal side. This part of the vas deferens, which comes very near its fellow, lilated and sacculated, like the adjacent seminal vesicle, and is known the ampulla. Close to the base of the prostate gland the sacculans disappear, and the duct, having become very narrow, is joined the outer side at an acute angle by the duct of the seminal vesicle, and the ejaculatory duct is formed, which will be presently described. t the structure and development of the vas deferens, see pp. 737 d 753















936


A MANUAL OF ANATOMY


Seminal Vesicles. —These are two in number, right and left, and between the base of the bladder and the rectum. They are sacculat reservoirs for the seminal fluid, and each is conical, being about 2 incl long, and about J inch broad at the widest part. The broad end free, and looks upwards, outwards, and backwards. It is covei posteriorly in its upper part by the peritoneum, which forms the rec vesical pouch, while anterior to it is the ureter as that is about to p; through the bladder. The upper ends of the two seminal vesicles ; wide apart, and the bottom of the recto-vesical pouch descends betwf


AnalCanal

Bulb of Corp.

Spong.


Ureter


V. Def. Bladder


Prostate


Fig. 549.—Median Sagittal Section through Male Pelvis.


them for a short distance. The lower end of each, which is nari and free from sacculations, approaches its fellow, the vasa deferer intervening. This lower end represents the duct, which, as stat joins the vas deferens at an acute angle close to the base of the prost gland, and so gives rise to the ejaculatory duct. For the struct and development of the seminal vesicles, see p. 958.

Ejaculatory Ducts. —These are two in number, right and left. E«  is formed by the union of the duct of the seminal vesicle with the deferens close to the base of the prostate gland; it is about 1 inch





THE ABDOMEN


937


ngth. The two ducts pass downwards, forwards, and inwards through e prostate gland between the middle and lateral lobes, and each enters e lateral wall of the prostatic utricle to terminate in a minute aperture i the lateral margin of the opening of the prostatic utricle. For the ructure and development of the ejaculatory ducts, see p. 955. Prostate Gland. —This gland surrounds the first ij inches of the ethra. It is firm in consistence, and in shape and colour resembles chestnut—that is to say, it is conical and of a reddish-brown colour, is subject to much variety in size, but its average measurements ay be stated as follows: the transverse diameter at the base is about inches; the vertical diameter from base to apex is about ij inches;


Sperm. Cord Corp. Cavern.


t \

/ \ >

Coccyx Rectum


Fig. 550 -—Transverse Section at Level of Coccyx (after Symington).

id the antero-posterior diameter is about f inch. The average weight

the organ is about \\ drachms. The gland is situated fully ij inches from the anus, and its anterior irface is about f inch below and behind the lower part of the symphysis ubis. It presents a base, an apex, a posterior or rectal surface, an iterior or pubic surface, and two lateral surfaces. The base, which directed upwards, surrounds the urethra, and is intimately connected ith the vesical wall. Notwithstanding this, however, there is a supernal line of demarcation between the two, which takes the form of an mular groove, occupied by a portion of the prostatic venous plexus, be ejaculatory ducts enter the base close to the upper part of the asterior or rectal surface, where there is a small transverse cleft died the prostatic fissure. The apex is directed downwards, and is





















938


A MANUAL OF ANATOMY


the most dependent part of the organ. It is in contact with the super layer of the perineal membrane. The posterior or rectal surface is f and triangular. It is directed backwards and slightly downwar and is set upon the anterior wall of the rectum, from which it is separal by the recto-prostatic lamina of the visceral portion of the pelvic fast This surface is accessible to manipulation on introducing the finger ir the anal canal, and carrying it up for fully ij inches. The anterior pubic surface, which is convex, is so much projected as to be really anterior round border which separates the two lateral surfaces. Itl about § inch behind the lower part of the symphysis pubis, from wh: it is separated by a portion of the prostatic venous plexus, the ret pubic pad of fat, and the medial pubo-prostatic ligaments. 1 anterior surface projects between the anterior borders of the levato ani muscles. The lateral surfaces are convex, and stand out in 1 relief. Each is embraced by the anterior fibres of the correspond] levator ani, which constitute the so-called levator prostatae muse When an accessory pudendal artery is present it passes over the late surface, and might be endangered in lateral lithotomy.

The gland is usually regarded as composed of three lobes, t 1 lateral and a middle, but, though the middle lobe can usually demarcated without much difficulty, there is no external indicati of any separation between the lateral lobes. The lateral lobes foi the chief bulk of the gland, and they meet and become continuous front of and behind the prostatic portion of the urethra, forming t anterior and posterior commissures. The middle lobe represents tl part of the basal portion of the gland which is wedged in between t ejaculatory ducts and prostatic utricle behind and the urethra in fra and which lies just below the apex of the trigonum vesicse. It is i: portant to note that the middle lobe lies behind the commencement the urethra. It is liable to become hypertrophied in old age, and m then produce undue elevation of the uvula vesicae in the interior of t bladder, which is a natural product of it. In this manner, by blocki the internal orifice of urethra, it may not only give rise to difficulty micturition, but may also obstruct catheterization.

The prostate gland is traversed by the first i J inches of the ureth: The ejaculatory ducts are also contained within the gland, in which th pass downwards and inwards between the middle and lateral lob' For the structure and development of the prostate gland, see pp. 9 and 960.

Urethra. —The male urethra commences at the internal orifice urethra of the bladder, and terminates at the extremity of the gla penis in a vertical fissure, called the external orifice of urethra. It about 8 inches in length, and is divided into three portions, whit from the bladder outwards, are called prostatic, membranous, a spongy. The prostatic and membranous portions constitute t non-penile part of the canal, and the spongy portion, being contain within the corpus spongiosum of the penis, represents the per part.


THE ABDOMEN


939


rhe prostatic portion of the urethra is the part of the canal which ontained within the prostate gland. It is inches in length, its course is almost vertical, there being a slight curve with the

avity directed forwards. It is spindle-shaped, being wider at the re than at either end, and at its upper or vesical end it is rather sr than at the lower end. Its diameter at the centre, which is the est part of the entire canal, is rather more than ^ inch; at the upper r esical end it is rather less than this, and at the lower end it is still . This portion of the urethra, though surrounded by the -prostate id, is the most dilatable part of the whole canal. Close to the Ider, however, it usually offers some resistance to the passage of an rument. Its walls are anterior and posterior, the latter being often ken of as the floor. These walls are in contact with each other, spt during the passage of fluid, and the mucous membrane is thrown ) longitudinal folds. The posterior wall presents along the middle


Median Umbilical Ligament


ig. 551.—Section of the Bladder and Penis to show the Urethra.

i a prominent narrow elevation of the mucous membrane, called the thral crest (verumontanum). It is about f inch long, and comnces either a little below the urethral orifice of the bladder or at the r er end of the uvula vesicas. As it descends it gradually becomes re prominent, assuming a height of about J inch, and then rapidly >sides. It is due to a thickening of the submucous tissue, which lses an elevation of the mucous membrane. On account of this protion a transverse section of this portion of the urethra is curved or scentic, with the convexity directed forwards. On either side of the st there is a longitudinal groove, called the prostatic sinus, into which ^ majority of the prostatic ducts open. A few of these ducts, howT from the middle lobe open in the median line above the crest, or, he crest commences at the lower end of the uvula vesicae, upon its per part. Immediately below the most prominent part of the crest

e is the opening of a small blind recess, called the prostatic utricle



94°


A MANUAL OF ANATOMY


(sinus pocularis). Its direction is upwards and backwards behind t' middle lobe of the prostate, and it is from £ to J inch in length. It somewhat flask-shaped, being narrow at its urethral orifice, but e panded at its deep csecal end. It may extend beyond the prostate ai is sometimes bifid. Upon the lateral margins of its orifice are the minu openings of the ejaculatory ducts. The utricle represents the uter and vagina in the female, being developed from the fusion of the posted or caudal ends of the para-mesonephric ducts.

When the middle lobe of the prostate becomes hypertrophied blocks the urethral orifice of the bladder, as has been stated, by press! the uvula vesicae over it from behind, and so gives rise to difficulty micturition, and obstructs catheterization. When both lateral lob become uniformly hypertrophied, the prostatic portion of the ureth undergoes increase in length. When only one lateral lobe is involv in the hypertrophy it presses against the urethra, and, producing d tortion of the canal, gives rise to difficulty in micturition, and oft considerable obstruction in catheterization.

Structure. —The mucous membrane of the prostatic urethra surrounded externally by the inner circular muscular fibres of t prostate, and is covered internally by transitional epithelium.

The membranous portion of the urethra si;cceeds to the prostai portion, and extends from the apex of the prostate gland to the coi mencement of the spongy portion. It is contained, for the most pa: between the two layers of the perineal membrane, but it also exten for a short distance (J inch) beyond the inferior layer of that structm It is the shortest and narrowest part of the canal, with the except! of the external orifice of urethra. Its length is £ inch along the anteri wall, and J inch along the posterior, the difference being due to t fact that the membranous urethra passes into the spongy part in slanting manner at a point £ inch in front of the posterior extremi of the bulb. The back part of the bulb projects backwards for £ in over the posterior wall of the membranous urethra, and is here lyi in front of the inferior layer of the perineal membrane. It is in tl situation where a false passage is liable to be made in catheterizatic partly because the walls are here very thin, and partly by reason the backward extension of the posterior extremity of the bulb. T. diameter of the membranous urethra is £ inch. It lies about i m behind and below the inferior ligament of symphysis pubis, and ] direction is downwards and slightly forwards. It describes a geni curve, the concavity of which looks forwards and upwards towards t lower part of the symphysis pubis. As the membranous urethra pass through the superior layer of the perineal membrane, which is form by the parietal pelvic fascia, the fascia is prolonged upwards to foi part of the capsule of the prostate gland. Moreover, as it pierces t inferior layer of the perineal membrane about i inch below the syi physis pubis, it carries with it a prolongation from the margins of t urethral opening, which forms a fascial investment for the bulb, h tween the two layers of the perineal membrane the membranous ureth


THE ABDOMEN


94 1


irrounded by the fibres of the sphincter urethrae muscle, and the o-urethral glands lie behind it, one on either side of the middle


Structure. —External to the mucous membrane there is a layer of tile tissue, and outside this there is a layer of circularly-disposed 1 muscular fibres,

h are continuous I "* e ™ laic: vesic* /e with the circular Bell’s Muscle I ; Left Ureteric Opening

cular fibres of the itate around the proic urethra. External his, again, there are sphincter fibres of sphincter urethrae, mucous membrane is ned by columnar epium. The membranportion of the urethra ransverse section pre:s the appearance of ircular opening, the len of which is iched, this being due the longitudinal folds • which the mucous nbrane is thrown.

The spongy portion of urethra succeeds to membranous portion, is contained within corpus spongiosum of penis, and extends n a point \ inch in it of the posterior exility of the bulb and the inferior layer of perineal membrane the external orifice of thra on the extremity the glans penis. It is

nit 6 inches in length, External Orifice of Urethra

1 its calibre is unequal Fig oughout. It presents i dilatations, one situated in the bulb, the intrabulbar fossa (which •resents about the first ij inches of the corpus spongiosum), and

other in the glans penis, the latter being called the terminal sa (fossa navicularis). The intrabulbar fossa is about ij inches in gth, whilst the terminal fossa is about J inch long. The diameter


-Crest

-Opening of Utricle

Prostate Gland in Section (showing Prostatic Portion of Urethra)


-Membranous Portion of Urethra

Bulbo-urethral Gland of Left Side


Left Half of Bulb of Urethra

Left Crus Penis

Openings of Ducts of Bulbourethral Glands


-Spongy Portion of Urethra


- [-Left Corpus Cavernosum

-Urethral Glands and Lacunas

Urethrales


-Terminal Fossa

-Left Half of Glans Penis


-The Interior of the Male Urethra.

























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A MANUAL OF ANATOMY


of that part of the spongy urethra which intervenes between the in bulbar fossa and the terminal fossa is about J inch. At the extei orifice of urethra the calibre of the canal is diminished, this being narrowest part of the entire canal. The spongy portion at its o mencement is directed forwards for a short distance, and then be downwards. It thus describes a curve, which is situated about 2 inc from its commencement, the concavity being directed downwa: This curve is fixed, and corresponds with the angle of the penis, the sit tion of which is immediately in front of the penile attachment of suspensory ligament, where drooping of the organ takes place, walls of the spongy part of the urethra are in contact, except dui the passage of fluid. A transverse section of it, except in the gk presents a transverse slit with anterior and posterior lips. In the gk however, the slit is vertical with its lips laterally disposed. At upper end of the terminal fossa—that is, the end most remote from external orifice of urethra-—the vertical slit is modified by the addil of a short transverse slit, and so presents the shape of an inverted as follows, J_.

Structure. —The mucous membrane of the spongy portion is j vided with elastic tissue, and is very vascular. It is covered columnar epithelium , except in the glans, where it is of the strati squamous variety. Outside the mucous membrane is the subrnuc coat, which contains two layers of plain muscular tissue—inner loi tudinal and outer circular. External to the submucous coat ther a plexus of veins, which forms part of the corpus spongiosum. ' mucous membrane contains both simple and compound mucous glar called the urethral glands (glands of Littre), the openings of the dr of which are studded over the surface. In addition to these there other openings, which lead into small blind recesses, called the lacr urethrales, these openings being directed forwards. One lacuna, large size, called the lacuna magna, is situated on the roof of the fc navicularis about 1 inch from the meatus urinarius. The muc membrane which surrounds this lacuna is known as the valvule Guerin. Besides the foregoing openings, the ducts of the bul urethral glands open upon the floor of the bulbous portion of the uret. about 1 inch in front of the inferior layer of the perineal membrane.

There is sometimes a congenital deficiency in the floor of the spoi urethra, constituting the condition known as hypospadias. In ot cases the deficiency may be on the roof, and it is then known epispadias.

Lymphatics of the Male Urethra—Spongy Portion. —The lymphs vessels of the spongy portion communicate with those of the glans £ with the deep lymphatics of the penis, and in part through this conn tion drain to the deep inguinal and external iliac glands. Much of' lymph, however, from this region drains into vessels which, accc panying first the vessels of the bulb and later the internal pudic vess< finally pass to the gland or glands of the internal iliac chain , which situated near the origin of the internal pudendal artery.

ulbar and Membranous Portions. —The lymphatics of these portions to (i) the internal iliac glands, and (2) the inner chain of the external glands.

rostatic Portion. —The lymphatics of this portion join those of the

ance of the prostate gland, and pass to (1) the middle chain of xternal iliac glands, (2) the internal iliac glands, (3) the lateral l glands, and (4) the inner group of the common iliac glands. elvic Colon. —The pelvic colon succeeds to the iliac colon. It nences at the inner border of the left psoas major just anterior to jft sacro-iliac articulation, and terminates in front of the third sacral ibra, where it becomes continuous with the rectum. It is very ible in length, but measures on an average about 15 inches, and lly lies in the pelvic cavity, resting upon the bladder and rectum, ascending on either side of these viscera. It is surrounded by peri11m, which forms behind it an expanded wavy mesentery, called the 0 meso-colon, which contains between its two layers the branches ie lower left colic arteries and the superior rectal artery, with the jsponding veins. The root of this mesentery is composed of two 3, which become continuous at an acute angle. One limb takes an ird course along the inner border of the psoas major, and the other ss downwards over the sacral promontory to be attached to the rior surfaces of the first three sacral vertebrae. At its extremities, h are near each other, the mesentery is short, and the extremities of pelvic colon are necessarily fixed. The intervening portion, how, is long, and so allows of considerable mobility on the part of the ter portion of the attached gut. A very common course for the ic colon to take is to pass from the left wall to the right wall of the is, resting upon the bladder or uterus, then to pass backwards wing the posterior wall of the pelvic cavity until it arrives at the lie line, when it turns vertically downwards. A portion of it is itimes met with in the abdominal cavity.

tructure. —The chief difference in the structure of the pelvic colon, impared with the other divisions of the colon, affects the arranget of the longitudinal muscular fibres. Though arranged at first iree taeniae, these gradually become disposed as two broad taeniae, rior and posterior. When this has taken place, the longitudinal s almost surround the gut, except along the sides, in which situa3 the usual sacculations are formed. Appendices epiploicae are met over the pelvic colon.

Wood-supply. —The pelvic colon receives its arteries from the lower colic arteries, which are branches of the inferior mesenteric. The s pass to the inferior mesenteric vein, and ultimately into the al vein.

die lymphatics pass to the left lower pre-aortic glands.

die nerves are derived from the inferior mesenteric sympathetic

us.

tectum. —The rectum succeeds to the pelvic colon, and extends 1 the front of the third sacral vertebra to a point 1J inches in front of


and below the tip of the coccyx, where it pierces the pelvic diaphra^ and terminates in the anal canal. Its direction is at first downwa and slightly backwards, then vertically downwards, and finally doi wards and forwards. It is fully 5 inches in length, and its diameter the most part is about ij inches in the empty state, but it becor enlarged above the anal canal, this dilated part being called the ampi recti. When empty, its anterior and posterior walls are in contact, c in transverse section it appears as a transverse slit. The rectun destitute of a mesentery. The peritoneum covers the upper th laterally and anteriorly , but not posteriorly, the middle third be covered by peritoneum only anteriorly , whilst the lower third is f from serous covering. The level at which the peritoneum leaves 1 anterior surface of the rectum is usually about 3 inches above the an opposite the body of the fifth sacral vertebra.

The rectum, so far from being straight in man, presents both ante posterior and lateral curvatures. The antero-posterior flexures ; two in number, upper and lower. The upper curve extends from 1 third sacral vertebra to the posterior or rectal surface of the prost; gland, and its concavity is directed forwards. The lower curve, wh] is abrupt, corresponds with the rectal surface of the prostate, its c( cavity looking backwards, and containing the ano-coccygeal body. T lateral flexures are of importance, because they tend to obstruct t passage of instruments by giving rise to the rectal valves (Housto These flexures are usually three in number—upper, middle, and low The upper and lower flexures have their convexities directed towai the right, whilst the middle flexure has its convexity directed towai the left. In the concavities of these flexures the rectal wall becoir inflected, and so gives rise to more or less prominent shelves of mucc membrane, which are known as the rectal valves. The lateral infk tions and resultant valves are associated with the erect posture of rm which posture throws considerable pressure upon the anal aperture ai its sphincter muscles. They are best marked in the distended recta and the lateral flexures are brought about in the following manner: T longitudinal muscular fibres of the rectum are rather shorter than t gut to which they are applied. Moreover, they are principally dispos' in two stout broad sheets, one on the anterior and the other on t. posterior wall, there being very few longitudinal fibres along the latei walls. The shortness of these longitudinal fibres therefore throws tl rectum into lateral flexures on account of the sparseness of the lon£ tudinal fibres at the sides. These lateral flexures may be taken representing the sacculations of the other parts of the colon.

Relations— Anterior. —The recto-vesical pouch of peritoneum f ( a short distance, usually containing coils of small intestine or of pelv colon; the base of the bladder, seminal vesicles, and vasa deferentia, wf the intervention of the recto-vesical lamina of the visceral pelvic fasci; and the posterior or rectal surface of the prostate gland, with the inte vention of the recto-prostatic lamina of the visceral pelvic fascia. J the female the anterior relations are (1) the recto-uterine pouch peritoneum (pouch of Douglas), with a few coils of small intestine or dvic colon, in front of which are the posterior surface of the body of e uterus and the upper part of the posterior wall of the vagina; and ) the greater portion of the posterior wall of the vagina. Posterior .— le lower three sacral vertebrae, coccyx, levatores ani, and ano-coccygeal idy; the median and lateral sacral vessels, sacral lymphatic glands, cral nerves, and sacral sympathetic trunk. Behind the rectum there a large amount of areolar tissue. Lateral .—The pelvic sympathetic sxuses, levatores ani, and coccygei muscles, the lateral divisions of e superior rectal artery, and the corresponding veins.

Anal Canal. —This is the terminal portion of the large intestine, extends from the lower end of the rectum, where that has pierced e pelvic diaphragm at a point correonding to the apex of the prostate md, to the anus, and it is the part rich is surrounded by the sphincter uscles. It is about i-| inches in igth, and its lateral walls are in ntact, so that in transverse section appears as an antero-posterior slit, which respect it differs from the ctum proper. Its direction is downirds and backwards, and its antero(sterior diameter is from \ to f inch.

Relations. — Anterior. —The bulb of e penis, the base of the perineal smbrane, and the membranous part the urethra. In the female the rineal body is anterior to it, and parates it from the lower end of e vagina. Posterior .—The ano-coccyal body. Lateral .—The fat of the ririo-rectal fossae. The anal canal is )sely guarded by muscles in the folding manner and to the following tent: most internally is the sphincter

i internus continuous with the circular muscular fibres of the rest the gut; outside this are the longitudinal muscular fibres markedly enforced by the fibres of the levator ani, which here run longidinally; and most externally is the sphincter ani externus. For e structure and development of the rectum and anal canal, see 960.


Fig. 553.—Diagram of Structure of Rectum and Anal Canal.

L, C, longitudinal and circular fibres of wall; the circular fibres thicken below to form the internal sphincter (IS) ; ES, external sphincter; LA, levator ani.


Parts felt per Rectum in Catheterization. —A catheter having been passed k) the bladder, the following parts, in order from before backwards, may be t through the anterior wall of the bowel on the introduction of the index S er: (1) the membranous portion of the urethra; (2) the posterior or rectal rface of the prostate gland; and (3) the apical part of the external trigone of 3 bladder, destitute of peritoneum, with a vas deferens on either side, and very






946


A MANUAL OF ANATOMY


near each other—indeed, almost touching. During this examination the fin may come in contact with the lower left, and perhaps the right horizontal folc rectum.

Median Sacral Artery. —This vessel arises from the posterior asp of the abdominal aorta just above the bifurcation. Its course downwards in the middle line, behind the left common iliac vein a the hypogastric sympathetic plexus, and it rests in succession uj the following parts: the lower half of the body of the fourth luml vertebra and the disc between it and the fifth, the body of the fr lumbar and the disc between it and the first sacral vertebra, and 1 pelvic surfaces of the sacrum and coccyx. In the pelvis it lies wit] the root of the pelvic meso-colon, being covered by a portion of i pelvic colon, as low as the third sacral vertebra, and beyond that il placed behind the rectum. On reaching the tip of the coccyx terminates in the coccygeal body. The branches of the artery are follows: anterior or rectal to the posterior wall of the rectum, where tl anastomose with the superior and middle rectal arteries; lateral to i front of the sacrum and coccyx, which anastomose with the late sacral arteries; and terminal to the coccygeal gland. The vessel usua furnishes a fifth pair of lumbar arteries, which wind round the sides the body of the fifth lumbar vertebra.

The median sacral artery represents the caudal aorta of anima and its lateral branches are serially homologous with the lumt branches of the abdominal aorta.

The median sacral vein is at first arranged as two venae comiti but these subsequently unite to form a single vessel, which usuaj terminates in the left common iliac vein.

Glomus Coccygeum. —This so-called gland is situated in front of t tip of the coccyx. It is about the size of a small pea, and is compos of a few nodules which are held together and invested by connecti tissue. It receives the terminal twigs of the median sacral artery, structure it consists of groups of polyhedral cells united by connecti tissue, and permeated by blood-capillaries and sympathetic ner\ filaments. It is in some respects similar to the carotid body , whi is situated behind the common carotid artery of each side close

its bifurcation, but differs from it in not containing chromap] cells.

Sacral Glands. —This group comprises a few lymphatic glands whi< he in front of the sacrum to the inner side of the second and third saci foramina. They receive their afferent vessels from the various peh viscera, as well as from the posterior wall of the pelvis; their effere vessels pass to the middle chain of common iliac glands.

Sacral Sympathetic Trunk. —This is situated close to the inner si( of the anterior sacral foramina. The two trunks, right and left, co verge as they descend, and in front of the coccyx they are connect* by a loop which sometimes presents a single ihedian ganglion, called tl ganglion impar or coccygeal ganglion. The number of ganglia on ea( trunk is usually four.


Branches.— (i) Grey rami communicantes, which spring from the rlia. and pass to the anterior primary divisions of the sacral and ygeal nerves. These rami are very short. (2) Visceral branches nail size which pass from the upper part of the pelvic sympathetic l. (3) Parietal branches, which are distributed over the front of sacrum, and which communicate with those of the opposite side, s to form a plexus upon the median sacral artery. From the terminal 1 and ganglion impar (when present) branches proceed to the front tie coccyx and glomus coccygeum. The ganglia of the sacral trunk lot receive any white rami communicantes from the sacral nerves,

e, under the name of the pelvic splanchnics, going directly to the dc plexus.

Levator Ani — Origin. —(1) The posterior surface of the body of the is in its lower part, below the attachment of the medial pubostatic or anterior true ligaments of the bladder, and above the ichment of the parietal pelvic fascia; (2) the internal surface of the ietal pelvic fascia along the arcus tendineus (white line) ; and (3) the dc surface of the spine of the ischium in its lower part, below the

ygeus. Insertion. —(1) The side of the lower part of the coccyx; (2) the -coccygeal raphe, where it meets its fellow of the opposite side; the wall of the anal canal, where the fibres blend with the longiinal fibres of the gut, and ultimately pass with them between the srnal and internal sphincter muscles to be attached to the skin and the anus; and (4) the anal raphe and the perineal body, where muscle again meets its fellow of the opposite side.

The levator ani is a broad, flat, and thin fleshy muscle, the direc1 of which is downwards, inwards, and backwards; with its fellow he opposite side it forms an incomplete muscular floor to the pelvic ity. It is covered on its pelvic aspect by the visceral portion of the dc fascia, and on its perineal aspect by the anal fascia, and in this mer a separation is formed between one half of the pelvic cavity and ischio-rectal fossa of the same side.

The anterior border is free close to the body of the pubis, but a little her back it passes downwards upon the side of the prostate gland he male, or vagina in the female; farther back still it meets its fellow he opposite side, between the prostate gland and the commencement he membranous part of the urethra on the one hand and the rectum the other, or between the vagina in the female and the rectum, the Ting taking place in the anal raphe. Between the anterior borders

he two muscles the membranous part of the urethra in the male, !• the vagina and urethra in the female, leaves the pelvic cavity. The erior or pubo-prostatic fibres are sometimes spoken of as the levator statae. The posterior border adjoins the coccygeus muscle.

The muscle is often divided on morphological grounds into two ts, the pubo-coccygeus and the ilio-coccygeus, the coccygeus muscle If constituting the ischio-coccygeus. The anterior fibres of the >o-coccygeus descend on the sides of the prostate gland and vagina,


94 8


A MANUAL OF ANATOMY


supporting these, and in strong contraction compressing them; posterior fibres of this part pass almost directly backwards, lying on i superior surface of the ilio-coccygeus muscle; but not all of these fib reach the coccyx, some ending immediately behind the anal canal joining the corresponding fibres of the opposite side to form the so-cal pubo-analis muscle. The ilio-coccygeus arises mainly from the ar< tendineus and the pelvic surface of the ischial spine, but its fibres cam infrequently be traced upwards underneath the arcus, particularly front, to become continuous with the outer surface of the upper part the parietal layer of pelvic fascia.

Nerve-supply. —(i) The anterior primary divisions of the third a fourth sacral nerve on its superior surface, and (2) the perineal brar of the pudendal nerve (deep division) on its deep surface.

Action. —(1) To elevate and support the floor of the pelvis, tl diminishing the vertical measurement of the abdominal cavity; (2) pull up the wall of the anal canal over the contained faeces, and so ass in their expulsion; (3) to pull the anal canal towards the symphy through the action of the pubo-analis muscle, and so straighten to soi extent this portion of the alimentary canal; (4) to elevate and compn the prostate gland in the male and the vagina in the female; and (5) flex the coccyx.

Coccygeus (Ischio-coccygeus) — Origin. —(1) The pelvic surface the spine of the ischium, above the origin of the posterior fibres of t levator ani; and (2) slightly from the inner surface of the parietal peh fascia, above the ischial spine.

Insertion. —The side of the upper two coccygeal and lower b sacral vertebrae.

Nerve-supply. —The anterior primary divisions of the fourth a: fifth sacral nerves.

Action. —To flex the coccyx.

The coccygeus is a thin, flat, triangular muscle, the fleshy fibi having a large admixture of tendinous fibres. The internal or peh surface is related to the visceral pelvic fascia, coccygeal plexus ai rectum, and the external surface to the sacro-spinous ligament. T superior border is adjacent to the pyriformis, with the intervention the structures which leave the pelvis below that muscle. The inferi border adjoins the posterior border of the levator ani. The muscle continuous with the sacro-spinous ligament, which is made by chang in its fibres.

The coccygeus muscle is to be regarded as a detached portion the levator ani.

The levatores ani and coccygei muscles form the pelvic diaphragm which presents a superior concave and an inferior convex surfac The greater part of this diaphragm is formed by the levatores ani, ar this part of it gives passage in the middle line to the rectum.

Pyriformis— Origin. — (1) By three fleshy slips from the anteri< surfaces of the second, third, and fourth sacral vertebrae, which a interposed between and lie lateral to the adjacent anterior sacr


THE ABDOMEN


949


nina; (2) the deep surface of the sacro-tuberous ligament; and tie posterior border of the ilium immediately below the posterior ior spine.

nsertion. —An impression on the upper border of the greater troter of the femur near its centre.

Verve-supply. —Two branches from the sacral plexus, more Ocularly from the dorsal divisions of the first and second sacral es.

ction. —Lateral rotator of the thigh.

he intrapelvic portion of the muscle is covered by a prolongaof the parietal pelvic fascia, called the fascia of the pyriformis, it supports the nerves of the sacral plexus, branches of the anterior

ion of the internal iliac artery, and pelvic colon. For the extraic portion, see Gluteal Region. Ibturator Internus. — Origin. —(1) The internal surface of the rator membrane; (2) the posterior surface of the body and inferior is of the pubis, and ramus of the ischium; (3) the inclined plane of ischium, extending as far back as the greater sciatic foramen, and ly as high as the iliac portion of the pectineal line; and (4) the stal pelvic fascia covering the muscle.

'nsertion. —The medial surface of the greater trochanter above and ont of the trochanteric fossa.

Verve-supply. —The nerve to the obturator internus from the sacral us.

1 ction. —Lateral rotator of the thigh.

Relations of Intrapelvic Part— Medial.— As low as the arcus tenus the internal surface of the muscle is covered by the parietal ic fascia and peritoneum with the extra-peritoneal areolar tissue, is directed towards the pelvic cavity. The obturator vessels and ie here lie between the extra-peritoneal areolar tissue and the etal pelvic fascia. Below the level of the arcus tendineus the Lial surface is still covered by the parietal pelvic fascia, which concts the pudendal canal. This portion of the muscle lies upon the ral wall of the ischio-rectal fossa. Lateral.— The internal surface the obturator membrane, and the surrounding bone. For the ‘a-pelvic part of the muscle, see p. 535.

Structure of the Viscera of the Male Pelvis.

The Bladder.

The wall of the bladder is composed of four coats serous, muscular, mucous, and mucous.

The serous coat is formed by the peritoneum, and is confined to superior surface and upper part of the base. It forms the false

ments of the viscus. . .

The muscular coat consists of plain muscular tissue, which is mged in three layers—external longitudinal, middle circular, and Tnal longitudinal.


95°


A MANUAL OF ANATOMY


The external longitudinal fibres are most apparent on the supei and inferior surfaces. Laterally they are scarce, and are dispo: in an interlacing manner. They have an independent bony atta ment to the posterior aspects of the bodies of the pubic bones n the lower part of the symphysis, where they constitute the so-cal pubo-vesical muscles. They then pass within the medial pubo-prosta ligaments to the prostate gland. Having covered the infero-late surfaces of the bladder as far forwards as the apex, some of them ; there prolonged along the median umbilical ligament for a short c tance, whilst others turn to the superior surface, over which they p to the base. Having descended upon the base, they enter the prost; gland, where they blend with its muscular tissue. The longitudi stratum has been called the detrusor urinse muscle from its suppos function in expelling the urine from the bladder.

The middle circular fibres are somewhat indistinct, and more less reticular over the greater part of the viscus. In the region wh the fundus and infero-lateral surfaces meet they become more distin and near the spot where the urethral opening is situated they forn tolerably well-marked annular bundle, known as the sphincter vesi( beyond which they are continuous with the muscular tissue of i prostate gland.

The internal longitudinal fibres are somewhat indefinite, and c chiefly recognizable on the inferior surface.

When portions of the mucous membrane project between 1 scattered muscular bundles, the bladder is said to be sacculated. Wh on the other hand, the muscular bundles become hypertrophied fr< any cause, such as enlarged prostate or stricture, they give rise inward projections of the mucous coat, which are arranged in a coarsi reticular manner, a condition known as the fasciculated bladder.

The submucous coat is situated between the muscular and muco coats, which it connects in a loose manner for the most part, and composed of areolar tissue with an admixture of elastic tissue, serves as a bed in which the arteries and nerves subdivide befc entering the mucous coat.

The mucous coat is soft in consistence, and of a pinkish colour health. It is continuous with the mucous membrane of the urete and urethra, and over the greater part of the empty bladder is thnn into folds, which, however, disappear as the viscus becomes distende This rugose condition is explained by the loose connection which exit between the mucous and muscular coats through means of the su mucous coat. Over the internal trigonum vesicae, however, to presently described, the mucous membrane is quite smooth, and al very sensitive. The mucous coat is covered by stratified transitior epithelium, similar to that of the ureters. In the most superficial lay the cells are cubical, and they present depressions on their deep si faces, which receive the round ends of the pyriform cells of the lay beneath. In the second layer the cells are pyriform, the round en being capped by the cubical cells of the first layer, and the narrow en


THE ABDOMEN


95i


deeply placed amongst the deeper cells. In the third and fourth

the cells are round or oval. )rifices of the Bladder. —These are three in number—namely, ral, and two ureteric. The internal orifice of urethra is the ng by which the urine leaves the bladder, and it is situated at osterior extremity of the infero-lateral surfaces, where they meet ase. This is the most dependent part of the viscus, and is surled by the base of the prostate gland. Immediately above the ral orifice the mucous membrane presents a short median vertical , which projects forwards over the orifice. This ridge is called the vesicce. It is produced by the middle lobe of the prostate gland, 3 much more conspicuous when that lobe is enlarged. The ureteric ngs assume the form of small, slit-like, somewhat elliptical aper, which are about i| inches apart, and an equal distance from the aal orifice, their direction being obliquely downwards and inwards, ureters, before so terminating, have pierced the vesical wall uely, lying in it for about £ inch, and in this manner reflux of is prevented.

rigonum Vesicae. —This is situated at the lower part of the basal ce, and the mucous membrane over it is so closely connected to the ular coat that it is always smooth, and so presents a marked •ast to the rugose condition of the mucous membrane over the of the empty bladder. The trigone (Fig. 546) assumes the form 1 equilateral triangle, the angles of which correspond with the iral and ureteric openings, whilst the sides are constructed by s connecting these openings. The interureteric ridge, called ier’s bar, is produced by a bundle of muscular fibres, and is slightly ex, with the convexity directed downwards towards the urethral

e. The fibres constituting the ridge, on reaching the ureteric es, run for some distance within Waldeyer’s sheath along and 3 rior to the ureter, with the longitudinal fibres of which they are lately continuous. When the fibres contract they pull the ureters iwards and inwards, increasing their obliquity, and thus diminishmy tendency to regurgitation of urine when contraction of the ier occurs; they moreover bring the duct more definitely within the 3 of the arched muscular fibres which surround the intraparietal ion of its course, and so still further diminish any such tendency, urethro-ureteric ridge on either side is also produced by a bundle of 'ular fibres, which are, however, very often indistinct, these bundles ^ known as the muscles of Bell. The uvula vesicae is situated at lower part of the trigone in the middle line above the urethral

e. rtimen of the Empty Bladder. —This is very small, and is composed wo limbs, anterior and posterior. The anterior limb, which is , lies almost horizontally in front of the urethral orifice, and is ted by the juxtaposition of the superior and inferior walls. The ’rior limb, which is short, is directed upwards and backwards, and rmed by the juxtaposition of the back part of the superior wall


952


A MANUAL OF ANATOMY


and the base. The anterior and posterior limbs join each other at t urethral orifice, and are there continued onwards into the lumen the prostatic urethra. A triradiate appearance is thus impart to the lumen of the empty bladder and of the prostatic urethra, t three rays diverging from a central point—namely, the internal orifi of urethra—one ray being urethral and two vesical, of which latter o: is the anterior limb of the vesical lumen and the other the posted limb.

The Infantile Bladder. —The bladder in early life is pyriform. T narrow end is directed downwards, and is on a level with the upp border of the symphysis pubis, from which point it gradually descen as age advances. The broad end is directed upwards, and lies in t hypogastric region of the abdomen. The base is absent at this perio and the anterior surface of the viscus, devoid of peritoneum, is in co tact with the posterior surface of the anterior wall of the abdome which is likewise destitute of peritoneum. There being no base, t bottom of the recto-vesical pouch of peritoneum lies close to the ba of the prostate gland.

Ligaments of the Bladder. —These are classified as false and tri ligaments. The false ligaments are formed by the peritoneum, ai are five in number as follows: two posterior , which represent the laterall disposed lips of the mouth of the recto-vesical pouch; two lateral , rig] and left, which represent the reflection of the peritoneum from eac lateral border of the bladder to the corresponding lateral wall of tl pelvis; and superior , which is the reflection of the peritoneum from tl apex of the bladder to the posterior surface of the anterior abdomin wall along the median umbilical ligament. The true ligaments a: also five in number as follows: two lateral pubo-prostatic y right and lef which are formed by the vesical layers of the visceral portion of tl pelvic fascia on the sides of the bladder; two medial pubo-prostati which are the reflections of the visceral pelvic fascia from the back * the bodies of the pubic bones near the lower part of the symphysis i the neck of the bladder, and which pass in their course over the anteri< surface of the prostate gland; and superior , which is the median un bilical ligament. Each medial pubo-prostatic ligament contains son of the external or longitudinal muscular fibres of the bladder.

Blood-supply—Arteries. —These are as follows: (i) superior vesica from the umbilical artery; (2) inferior vesical, from the anterior divisic of the internal iliac; (3) vesical, from the intrapelvic portion of tl obturator; (4) vesical, from the intrapelvic portion of the inferior glutea and (5) branches from the uterine and vaginal arteries in the female.

Veins. —These are very copious, and are arranged in two plexusesvesical and prostatic. The vesical plexus is situated over the fundi and sides of the bladder, and its blood is conveyed into the prostat plexus. The prostatic plexus is composed of two parts continuous wit each other. Its blood is conveyed by one or more veins into the intern; iliac vein.

Lymphatics. —These pass to the external and internal iliac glands.



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953


erves. —Each half of the bladder receives sympathetic and spinal 3 from the following sources: (i) the pelvic plexus of the symetic, which contains spinal fibres from the third and fourth sacral es (sometimes also from the second), these being known as th epelvic ichnics ; and (2) special twigs from the pelvic splanchnics, which )e traced independently to the bladder. It is to be noted that the ler also receives spinal fibres from the upper two or three lumbar es through (a) the ganglia of the lumbar sympathetic trunk, (b) the c plexus, ( c ) the hypogastric plexus, and ( d) the pelvic plexus.

Structure of the Penis.

lorpora Cavernosa. —Each corpus cavernosum has a strong capsule, d the tunica albuginea. This tunic is composed of fibrous, plain

ular, and elastic tissues. It is disposed in two laminae—external internal. The fibres of the external lamina are arranged longilally, and are common to both corpora cavernosa. The fibres of nternal lamina run circularly round each corpus cavernosum, and le middle line those of each side meet and are prolonged inwards septum, which is imperfect except near the roots of the penis, e* traversed by vertical clefts. This partition is called the septum, n the inner surface of the tunica albuginea strong trabeculae are n off, which penetrate into the interior of the corpus cavernosum. le trabeculae, which aie fibro-muscular and elastic in character, are nged in a reticular manner, and enclose the cavernous spaces of the tile tissue. The deep artery of penis lies in the centre, and, in tion to this chief vessel, several other arteries, derived from the al artery of the penis, enter it from the surface. The branches of e arteries run in the trabeculae, and terminate in capillaries, which

their blood directly into the cavernous or intertrabecular spaces, e of the small arteries in the trabeculae are thrown into spiral loops,

h project into the intertrabecular spaces. Such vessels are called helicine (spiral) arteries (Muller). From the intertrabecular spaces radicle veins proceed, and by them the blood is returned from the

in.

Corpus Spongiosum. —This differs from the corpora cavernosa in g destitute of any bony attachments. Its length is about 6 inches, it is expanded at either end. It is divided into a bulb, body, and s. The glans has been already described (see p. 713 et seq .) The bulb esents about the first i\ inches of the corpus spongiosum, and at widest part it measures § inch. It is surrounded by the bulbolgiosus muscles, and its enlarged posterior extremity rests upon the t of the inferior layer of the perineal membrane, where it is about ch in front of the anus. The body is cylindrical. It has a capsule unica albuginea, but this is very thin. Within the capsule there is erectile tissue, which resembles that of the corpora cavernosa, igh of a finer texture and not so well developed; in the centre is the igy portion of the urethra. The corpus spongiosum is traversed


954


A MANUAL OF ANATOMY


by the arteries of the bulb, right and left, which are branches of 1 internal pudendal arteries. They are situated underneath the ureth canal, one on either side of the middle line.

The venous blood of the corpora cavernosa and corpus spongiosi is returned by the dorsal vein of the penis, and by the internal puden< venae comites.

For the structure of the different parts of the urethra, see p. 940

The glans penis and corpora cavernosa are developed from the genital ei nence, and the corpus spongiosum is developed from the genital folds.

Development of the Bladder and Urethra—The Allantois (see pp. 31, 32, s

45)-—The intra-embryonic part of the allantois is at first directly continu<


Dorsal Vein of Penis


Dorsal Artery of Penis

Dorsal Nerve of Penis


Septum


Skin


Dartos Muscle


Fibrous Sheath-- ■ of Penis


Fibro-elastic Capsule of Corpus Cavernosum


Deep Artery of Penis


Corpus Cavernosum


' _Corpus Spongiosum


Urethra


Arteries of Bulb of Penis

Fig. 554. —Transverse Section of the Penis of a Child as seen

under a Low Power.


with the upper part of the bladder, but in the course of the second month lumen usually disappears, and then this portion is transformed into a fibre cord, which is called the urachus. It is, however, to be noted that the lum of the intra-embryonic part of the allantois may remain persistent for soi time, thus giving rise to the condition which is known after birth as an umbilic urinary fistula.

The cloaca, which is the common terminal chamber of the hind-gut ai allantois (Fig. 555), is divided by the cloacal septum into ventral and dors parts. These changes are illustrated in the figure, where the dividing ‘ septun ib seen to deepen from above. The dorsal compartment gives rise to the rectui the ventral compartment constitutes the uro-genital sinus, so termed becau the excretory ducts and subsequently the genital ducts open into it.

These ducts are indicated in Fig. 555. The mesonephric (or Wolffian) due reach the lateral walls of the cloaca, and when the septum extends down behii





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m they are left opening into the dorso-lateral aspect of the ventral compartnt. Later, as will be shown in the next paragraph, the ureteric outgrowth m the duct comes to open into the cavity, and the ultimate opening of the duct t a lower level. Th e para-mesonephric (or Mullerian) ducts now reach this lower el by passing along the mesonephric ducts, and thus reach the uro-genital sinus ow the dilatation which forms the bladder.

In the meantime the cloacal derivatives are changing their form rapidly, e cloacal membrane (shown as a black line in the first two stages in Fig. 555) es cranially at first, but is quickly swung round so that it comes to face in opposite direction. This is brought about by rapid mesodermal formation men the base of the body-stalk ( BS) and the membrane, along the sides of which extends for some distance; in this way the genital tubercle (G) comes into dence, and the mesodermal growth beside the membrane makes the genital Is continuous with the tubercle. Thus not only is the area of the membrane mg round on its non-growing caudal extremity, but the whole mesodermal


Fig. 555.— Outlines to show Cloaca at Different Stages.

Observe rotation of plane of cloacal membrane and division of the cavity.

wth encloses a new cavity which is added to the length of the uro-genital sinus; 3 can be appreciated from Fig. 556.

The urinary bladder is developed from the cephalic part of this elongated '-genital sinus. In the first section in Fig. 556 the mesonephric duct (W) ches a dilated part of the sinus above the lower end of the septum (S). In the ond section the duct is not shown, but the marked elongation of the sinus, in ping with the great external growth, is well shown, and the dilatation of the dder is much more evident. Each duct had a metanephric bud (ureter) sning into it at first some distance from the sinus. The upper part of the sinus,

held by the lower thickenings of mesoderm, begins to expand, extending n g the mesonephric duct in doing so; this expansion (Fig. 557) goes on round duct, the end of which is thus passively invaginated or intussuscepted into the dder cavity, where it rapidly atrophies, breaks up and disappears. This process s on until the expanding bladder reaches the ureteric opening, which is affected the same way, at its extreme end only, when the expansion ceases. Thus the ter comes to open into the bladder apart from the duct, and to its lateral side l above it.






956


A MANUAL OF ANATOMY


About this time the infra-umbilical portion of the belly-wall, hardly exist up to now, begins to grow, and the upper part of the sinus is gradually dra up with it; the lower part is, of course, fixed in the mesodermal condensatio Thus the bladder, carrying the ureter with it, is elongated in an upward directs The mesonephric duct, however, embedded in the topmost part of the cond sation, is held in position here. Thus its terminal piece, held below but dra up at its upper end, is embedded in and fused with the lining cells of the cor sponding wall of the sinus. This is indicated schematically in Fig. 558, wh the first diagram shows the dorsal wall of the sinus here including the end-piecf the duct (W), still visible almost as far as the level of the entrance of the ureter ( The next diagram shows how, by the breaking down of the (dotted line) vent wall of this included duct, its ultimate opening is left at the low level, while 1 ureteric opening is moving up. In this way the ejaculatory ducts come to oj below the level of the bladder.



Fig. 556. —Entodermal Cloaca of Embryos of 8-5 and 16 Mm., somewh

Schematized.

This part of the uro-genital sinus, in which the openings of the duct are k becomes the prostatic urethra or, in women, the whole urethra.

Membranous Urethra. —The membranous portion of the urethra is develoj from the caudal part of the uro-genital sinus.

Spongy Portion of Urethra. —The cloaca, the cavity (p. 45) common to 1 allantoic and intestinal terminations, is shut off from the exterior by the cloa membrane, consisting of entoderm and ectoderm, with a certain amount mesodermal cells between these layers. It extends at first from the tail pvoi nence to the body-stalk, and corresponds with the situation of the primitive stre> later it is more restricted in extent, being separated from the body-stalk mesodermal thickenings which make the genital eminence and the lower part the belly-wall, and from the tail prominence by a much smaller mesoderi growth which makes the ano-coccygeal region. The restricted area of cloa membrane, limited in this way, lies at the bottom of an external cloacal depress










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957


fossa, or ectodermal cloaca ; this is the cavity included between the external >odermal growths already mentioned. The internal or entodermal cloaca livided into rectal and uro-genital compartments in the course of the second



557.—Schemes to show how the Terminal Piece of the Mesonephric (Wolffian) Duct becomes invaginated within the Bladder as a Result of the Expansion of this Structure.


expansion finally involves the extreme end of the ureter, so that, when the invaginated parts disappear, the ureter and duct open separately into the cavity of the bladder.


Fig. 558.—Diagrams to illustrate Descriptions in the Text.

first two figures show the way in which the low level of insertion of mesonephric duct is gained. The third shows the curved uro-genital sinus, comprising the bladder dilatation (B); a pars pelvina (PP), into which the ducts (D) open; and a pars phallica (PPH), opening externally and prolonged on to the genital tubercle (T).

fih, and as this takes place a corresponding division of the external fossa )mes . apparent, due to a transverse mesodermal thickening—the perineal coinciding in position with the transversely disposed internal septum




95§


A MANUAL OF ANATOMY


(which has divided the internal cloaca) as this completes its growth. The and outer transverse septa thus become continuous as the division of the ( is completed.

The part of the cloacal fossa behind the perineal fold forms the anal di sion or proctodaeum, and the portion of the cloacal membrane which for is called the anal membrane. When the anal membrane disappears (; the third month) the anus becomes formed, and the rectal compartment ( cloaca now opens into the back part of the cloacal fossa. The uro-genital opens into the cloacal fossa in front of the perineal fold by means of a n; vertical cleft, called the uro-genital cleft. Leading backwards from the gi eminence there is a furrow, which ends at the uro-genital cleft. The g< eminence is continuous at the sides with the labio-SCrotal folds, which, exte: backwards, enclose the cloacal fossa and the cloacal membrane. The pos surface of the genital eminence presents a groove, which is continuous wit uro-genital furrow. The lips of this groove, by their subsequent meeting fusion, form a canal, which represents the part of the spongy urethra cont in the glans penis. Posterior to this the lips of the uro-genital furrow together and unite as far back as the uro-genital cleft, and thus convert the part of the cloacal fossa into a canal, which represents the spongy part c


o

Fig. 559 -—Four Simple Outlines to show Closure of Urethra Development of External Male Characters.

R, raphe formed by fusion of genital folds (GF).

urethra behind the glans. The spongy part is thus to be regarded as a for extension of the uro-genital sinus, which opens at the uro-genital cleft. \ the lips of the uro-genital furrow fail to meet and unite at any part, the c( tion known as hypospadias is produced, in which the spongy urethra o externally on the under surface of the body of the penis. It is to be n that, whilst the prostatic and membranous portions of the urethra are devel from the ventral or uro-genital compartment of the entodermal cloaca, the sp portion is developed from the anterior part of the ectodermal cloacal fossa posterior part of that fossa giving rise to the anus and anal canal.


Structure of the Seminal Vesicles.

Each seminal vesicle consists of a tube which is thrown int number of coils, these being held together by fibrous tissue. W these coils are undone, and the tube straightened out, it measi from 5 to 6 inches in length. Its upper end is closed, and along course several diverticula are met. Each seminal vesicle in its nat sacculated condition is surrounded by a sheath, which is derived f the recto-vesical lamina of the visceral portion of the pelvic fae:

.






THE ABDOMEN


959


in this sheath the tube has a fibrous wall composed of delicate is tissue, and within this there is a muscular coat, which is formed rin muscular tissue arranged in two layers—outer longitudinal nner circular. Within the muscular coat is the mucous coat, i presents a number of reticular ridges with intervening alveoli, ns bears a resemblance to honeycomb, in which respect it corre1 s with the mucous membrane of the ampulla of the vas deferens )f the gall-bladder, the last named having coarser meshes. The elium which covers the mucous membrane is of the columnar non?d variety.

ood-supply—Arteries. —These are derived from the inferior vesical, liddle rectal, the descending branch of the artery to the vas, and itrapelvic portion of the inferior gluteal.

tie veins are fairly large and numerous, and are disposed in a iorm manner. They communicate with the prostatic plexus, junphatics. —These go to the internal iliac glands.

Brves. —These are derived from the pelvic plexus.

ivelopment. —Each seminal vesicle is developed early in the fourth month liverticulum from the posterior or caudal part of the mesonephric duct, which the vas deferens originates. It begins to show dilatations at the e of this month.

Structure of the Ejaculatory Ducts.

he wall of each duct is composed of three layers as follows: an ' fibrous layer, which is very delicate; a middle muscular layer, >osed of an outer circular and inner longitudinal stratum; and an mucous layer, lined by columnar non-ciliated epithelium.

ivelopment. —Each duct is developed from the caudal part of the mesoic duct. The level of its opening is gained as described on p. 956 (Fig. 558).


Structure of the Prostate Gland.

he prostate gland is encased in a strong capsule, which is formed y by the visceral portion of the pelvic fascia, and partly by the tal pelvic fascia, in the following manner: the anterior wall of capsule is formed by the prostatic lamina, and the posterior wall ie recto-prostatic lamina, of the visceral portion of the pelvic 1; and on either side the capsule is joined by the corresponding of the superior layer of the perineal membrane (which is formed tie parietal pelvic fascia) after it has passed backwards over the ■ior border of the corresponding levator ani muscle. The capsule - material influence in fixing the prostate gland in its position. The ule is formed of concentric layers of fibrous tissue, within and een which lies the prostatic plexus of veins. The substance of the 1 is composed of two elements—muscular and glandular. The mlar tissue, which is of the plain variety, is arranged as (1) an mal, partly longitudinal and partly transverse layer, which lies


960


A MANUAL OF ANATOMY


beneath the fibrous capsule; and (2) an internal circular layer, wl surrounds the prostatic urethra, being continuous above with fibres of the sphincter vesicae, and below with those around the m branous portion of the urethra. Between these two layers the muse fibres pervade the gland in a decussating manner, so as to constru muscular reticulum, the meshes of which contain the glandular tis The chief part of the gland in front of the urethra is compose( muscular tissue. The glandular element consists of branched tub alveoli or acini, the walls of which are formed by a basement membi covered internally by columnar epithelium. The tubular alveoli into the prostatic ducts, the structure of which is similar to that ol gland-tubes. The ducts average twenty in number, ten on either 5 and they open by independent orifices upon the posterior wall of prostatic portion of the urethra, for the most part into the prost sinus on either side of the crest. The outer portion of the gk consists mainly of muscular tissue, and has received the name of a to distinguish it from the inner glandular portion—the medulla.

Blood-supply—Arteries. —These are derived from the inferior ves the middle rectal, and the intrapelvic portion of the inferior gluten

The veins form a copious prostatic plexus, which is most plen over the anterior and lateral surfaces. It receives in front the d( vein of the penis in two divisions, and discharges its blood by on more veins into the internal iliac vein. The prostatic plexus is li to become much enlarged in old age.

Lymphatics. —These pass to the external iliac, internal iliac, sa 1 and common iliac glands.

Nerves. —These are derived from the pelvic sympathetic plexus

Development. —The glandular part of the prostate is developed from epithelium of the uro-genital sinus. The epithelial cells in the course oj third month send out ramifying branches, which are at first solid, but si quently become tubular, and so form the glandular part. The outgro arise above and below the entrance of the mesonephric ducts, and from the of the urethra, and a small inconstant group may arise from its front 1 The muscular tissue develops during the fourth month from the surrour mesoderm.

Structure of the Rectum.

The wall of the rectum is composed of five coats—serous, fas muscular, submucous, and mucous.

The serous coat is formed by the peritoneum, and, as has 1 stated, is imperfect.

The fascial coat represents a sheath which is derived from visceral pelvic fascia. In front of the rectum it is composed of recto-vesical and recto-prostatic laminae, whilst posteriorly it is for by the rectal lamina of that fascia. It is best marked over the k third of the rectum, where the peritoneum is absent. Elsewhere comparatively thin, and over the peritoneal area it merges into subperitoneal areolar tissue.

The muscular coat is well developed, and is composed of p


THE ABDOMEN


961


cular tissue, arranged as an external longitudinal and internal a lar layer. The longitudinal layer is present all round the gut, attains its greatest development along the anterior and posterior s, where it forms two broad stout laminae. Along the sides it is ewhat sparse. The circular fibres form a continuous covering for rectum, and inferiorly they become increased in amount around anal canal, and so give rise to the sphincter ani internus. rhe submucous coat is composed of areolar tissue, and connects muscular and mucous coats in a very loose manner, so that the sr is thrown into a number of temporary folds in the empty conm of the gut. The internal haemorrhoidal plexus of veins is >edded in this coat.

rhe mucous coat is characterized by great thickness and vascularity, ealth, therefore, it has a reddish colour, and is capable of free movet upon the muscular coat. The mucous membrane is covered by mnar epithelium, and is provided with crypts of Lieberkiihn and phoid nodules. It is thrown into a number of folds in the empty e, but the majority of these are temporary, and become effaced n the gut is distended. There are, however, at least three permanent s, which constitute the horizontal folds of rectum. The mucous ibrane is also studded over with a number of minute tubular dessions, called rectal pits, which are surrounded at their deep ends by phoid tissue (Birmingham).

rhe horizontal folds of rectum (Houston’s valves) are horizontal

ldings of the wall of the rectum in certain situations. Each fold is centic or semilunar, and consists of (1) the rectal mucous membrane, the submucous areolar tissue, and (3) a variable amount of the ular muscular fibres. The folds are very variable both in number position, but are usually described as three in number. The most stant and best-developed fold is situated on the right wall about ches from the anus on a level with the body of the fifth sacral vertebra the bottom of the recto-vesical pouch of peritoneum. It is there: related to the fundus of the bladder. This fold is sometimes referred is the plica transversalis recti, and is occasionally annular. The

al muscular fibres (circular) which it contains constitute the soed sphincter ani tertius, or sphincter of Nelaton. The other folds much less definite, and are usually found one about an inch above the other about the same distance below the fold just described.

The horizontal folds are probably sustentacular in function, serving support the rectal contents. They may give rise to obstruction ing the introduction of instruments.

Structure of the Anal Canal.

The wall of the anal canal is composed of three coats muscular, imucous, and mucous. The muscular coat is composed of plain ocular tissue, arranged as an external longitudinal and internal ular layer. The longitudinal fibres are continuous with those of the

61


A manual of anatomy


962

rectum, and blending with them there are fibres of the ievator Inferiorly they pass between the internal and external sphincter be attached to the skin round the anus. Associated with the longitudinal fibres oil the posterior wall of the anal canal there an minute muscles (sometimes united into one), called the redo-coc muscles. These spring from the front of the coccyx and descend the posterior wall, where they blend with the longitudinal fibres.

There is nothing specially noteworthy in the submucous coat.

The mucous coat presents the anal columns and the anal va The anal columns (Morgagni) are six or more in number, and the form of permanent vertical folds, which are confined to the u two-thirds of the anal canal, where they are separated from each c

by longitudinal grooves. They composed of inflections of the mi membrane, which contain plain cular tissue belonging to the musci mucosae and small bloodvessels, stop short about § inch above the j T he anal valves are situated at lower ends of the anal columns a \ inch above the anus. They 1: the lower ends of the longitu* grooves, where they extend beb adjacent columns, and they be; resemblance to the valves which met with in veins. They are semil folds of the mucous membrane, ' free margins being directed upw; and above each valve there is a s recess or f sinus. 5 The anal valves sinuses are best seen in the child, tend to disappear as age advai The mucous membrane of the canal is replaced in the lower t (below the anal valves) by modified 5 and finally for the last few lines by ac skin with sebaceous glands and hair follicles; this skin in the neg pigmented like the skin covering the body, and terminates by joi the modified skin along a fine wavy line. In white races the junc is known as the white line of Hilton. In the upper two-thirds of canal the mucous membrane is lined by columnar epithelium , and in upper third it is provided with a few intestinal glands and lymp nodules. The wall of the lower third of the anal canal is linec epithelium, which gradually becomes more and more stratified as anal orifice is approached, and which is continuous at the anal ma with the epidermis. It is at the margins of the anal valves where modified epidermic epithelium gives place to the columnar epithel of the mucous membrane, and here also the modified skin of the k


Fig. 560. —Diagram of Structure of Rectum and Anal Canal.


L, C, longitudinal and circular fibres of wall : the circular fibres thicken below to form the internal sphincter (IS); ES, external sphincter; LA, levator ani.







THE ABDOMEN


963

1 of the canal becomes continuous with the mucous membrane of ipper two-thirds.

phincter Ani Internus. —This so-called muscle is merely a thickenif the circular plain muscular fibres of the gut. It is confined to the >n of the anal canal, and viewing it as an independent muscle, or er thickening of muscular tissue, it begins very near the upper end Le anal canal, and terminates about \ inch above the anus. Though liary to the external sphincter, the principal action of the internal ncter is to expel the contents of the anal canal.

lood-supply of the Rectum and Anal Canal—Arteries. —The rectum and anal l receive their arterial supply from (1) the superior rectal, which is a single

1; (2) the middle rectals, right and left; (3) the inferior rectals, right and left; [4) branches from the median sacral and inferior gluteal arteries, he superior rectal artery (superior hsemorrhoidal artery) is of large size, and e direct continuation of the inferior mesenteric. Having crossed the left non iliac vessels, it descends within the root of the pelvic meso-colon as is the third sacral vertebra, where the rectum commences. Here it divides two branches, right and left, which descend upon the sides of the rectum. 1 each of these divisions six or more branches are given off, which pierce ciuscular coat of the rectum about half-way down, and so enter the submucous in which they descend to lie ultimately within the anal columns. As these inal branches descend they give off twigs, which, by anastomosing with ches of the middle and inferior rectals, give rise to an arterial anastomotic ork in the submucous coat. The disposition of the two primary divisions e superior rectal artery on the sides of the rectum is to be borne in mind in )erformance of operations in this region.

t is important to bear in mind that while there is a free anastomosis between ower left colic arteries in the pelvic meso-colon, the anastomosis between the st branch of the lower left colic and the superior rectal is more restricted. a,ses, therefore, where it is desirable in the course of an operation to render pelvic colon more mobile by cutting through its mesentery, care should be n not to interfere with this low anastomosis, but instead to divide and tie 3r other of the upper branches of the lower left colic arteries.

•he middle rectal arteries (middle hsemorrhoidal arteries) are two in number, t and left, and are branches of the anterior divisions of the internal iliacs, 1 arising in common with the inferior vesicals. Having reached the sides ie rectum about its middle, they divide into branches, some of which supply muscular wall, whilst others enter the submucous coat to take part, along The superior and inferior rectals, in the anastomotic network.

"he inferior rectal arteries (inferior hsemorrhoidal arteries) are two in number, t and left, and each may be a single artery, or there may be two or three on side. In any case, they are branches of the internal pudendal, immediately

that vessel has taken up its position in the pudendal canal on the outer wall ie ischio-rectal fossa. Having pierced the wall of the pudendal canal, and ersed the fat of the ischio-rectal fossa, they approach the wall of the anal T where they break up into branches, some of which supply the muscular , including the external sphincter and adjacent fibres of the levator ani, st others pass into the submucous coat, where they take part, along with the

nor and middle rectals, in the anastomotic network already referred to. middle and inferior haemorrhoidal arteries of one side anastomose with F fellows of the opposite side.

he rectum also receives twigs from the median sacral and inferior gluteal ties.

feins. —The veins, all of which are destitute of valves, form two rich plexuses ternal rectal, situated in the submucous coat, and external rectal, lying § the exterior of the rectum, both being confined to its lower third. The


A MANUAL OF ANATOMY


964

internal rectal plexus, situated in the submucous coat, receives its radicles a set of vessels, termed anal veins, which commence beneath the skin of the c These anal veins ascend in the wall of the anal canal, some of them lying w the anal columns, and are reinforced by other veins from the anal wall. Ha given rise by their communications to the internal rectal plexus over the 1 third of the rectum, the blood is conveyed away from the plexus in two chai as follows: (1) the veins from the upper part of the plexus pierce the wall o: rectum, and open into the external rectal plexus; and (2) the veins from lower part of the plexus pass through the external sphincter to end in a pi on the outer surface of that muscle, in which the inferior rectal veins origii The external rectal plexus is situated on the outer wall of the rectum ove lower third, and is continuous below with the plexus on the outer surface ol external sphincter. It is from this external rectal plexus that the rectal v which correspond with the rectal arteries, arise. The superior rectal vein (supi hsemorrhoidal vein) leaves the plexus in two divisions, right and left, w ultimately join to form one vessel, the inferior mesenteric vein. It is there an indirect tributary of the vena portal vein. The middle rectal veins (mi hsemorrhoidal veins), right and left, terminate in the internal iliac veins. inferior rectal veins (inferior hsemorrhoidal veins), right and left, pass to internal pudic veins. Through means of the external rectal plexus a free ( munication is established between the systemic and portal venous channels, there being no valves, when the portal circulation is obstructed the condi known as haemorrhoids frequently results.

Lymphatic Vessels of Rectum, Anal Canal, and Anus—(1) Rectun

The lymphatics of the rectum can be divided into two groups, an up and a lower; the upper accompany the superior rectal vessels, after passing through small pararectal glands, which to the numbe four to seven lie directly on the muscular coat of the rectum underne its fascial covering, enter the glands in the pelvic meso-colon; the lo accompany the middle rectal vessels, and pass to a gland situated r the origin of the middle rectal artery.

(2) Anal Canal. —The lymphatics of the anal canal mainly acc< pany the inferior rectal vessels, coursing therefore below the levc ani, and draining into one of the internal iliac glands near the or of the internal pudendal artery; certain of them, however, upwards in the anal columns and join the lymphatics from rectum.

(3) Anus. —The lymphatic vessels of the anus pass to the superfi inguinal glands.

Nerves. —These are partly sympathetic and partly spinal, superior rectal artery conducts to the rectum and anal canal superior hsemorrhoidal sympathetic plexus, which is an offshoot fi the inferior mesenteric plexus, that in turn coming from the a0| plexus. The middle rectal arteries conduct the middle haemorrho sympathetic plexuses, which are offshoots from the pelvic plexus The spinal fibres are derived from the third and fourth sacral ner (sometimes also the second), and they belong to the pelvic splanchr They are further derived from the upper two or three lumbar ner all in the manner described in connection with the innervation of bladder. The fibres from the pelvic splanchnics carry motor impu to the longitudinal muscular fibres of the rectum and inhibitory pulses to the circular fibres; whilst the sympathetic fibres are moto



THE ABDOMEN


965


ards the circular fibres, and inhibitory as regards the longitudinal res. The anal canal, close to the external sphincter, receives twigs m the inferior haemorrhoidal branch of the pudendal nerve.

Development of the Rectum, Anal Canal, and Anus.

In man the cloaca becomes partitioned off into two tubular compartments by Did, called the cloacal or uro-rectal septum. The two compartments or canals dorsal and ventral respectively. The dorsal canal gives rise to (1) the rectum, 1 (2) the upper two-thirds of the anal canal, or the part above the anal valves, s ventral canal leads caudalwards from the opening of the allantoic diverticulum, 1 is called the uro-genital sinus or canal. The allantoic diverticulum and

uro-genital ducts open into it. The recto-anal and uro-genital canals are directed towards the cloacal mem,ne, which closes both of them ventrally and caudalwards. The uro-rectal turn is connected inferiorly with the cloacal membrane, and this membrane livided into two parts—namely, dorsal or anal, known as the anal membrane, 1 ventral or uro-genital.

The anal and uro-genital parts of the cloacal membrane are separated externj by a transverse fold, known as the perineal fold. This fold undergoes conerable thickening, and gives rise to the perineal body.

The anal membrane is soon sunk below the surface, producing thereby the il depression or proctodaeum. The depression consists of invaginated ectoderm ich meets the intestinal entoderm, and the two layers construct the anal memme, or anal part of the cloacal membrane. The condition of matters may be npared to the invagination of ectoderm, which forms the primitive oral cavity stomodaeum, and which, meeting with the entoderm of the pharyngeal part the fore-gut, forms the bucco-pharyngeal membrane.

The rupture of the anal part of the cloacal membrane gives rise to an aperture led the anus, through which the hind-gut and proctodaeum become continuous, e lower one-third of the anal canal—that is to say, the limited portion below i anal valves—is formed by the ectoderm of the anal fossa or proctodaeum. e time of disappearance of the anal membrane varies somewhat, but seems to usually in the third month.

In some cases the anal membrane—namely, that part of the cloacal memme which separates the hind-gut from the anal fossa or proctodaeum—is rsistent. Such a condition is known as atresia ani or imperforate anus.

The uro-genital part of the cloacal membrane becomes depressed, and so r es rise to the uro-genital fossa. When this part of the membrane ruptures,

5 uro-genital opening or Cleft is formed, by which the uro-genital compartment the cloaca—namely, the uro-genital sinus or canal—communicates with the terior.


THE FEMALE PELVIS.

The female pelvis contains the pelvic colon and rectum, with a few ils of the small intestine; the bladder and urethra; the uterus and gina; and the uterine appendages connected with the broad ligasnts—namely, the uterine tubes, the ovaries, with the epoophoron d paroophoron (the latter in early life); and the ligamenta teres of the erus. The arteries are the same as in the male, with the addition of •rtions of the ovarian arteries and the uterine arteries, and the subtution of the vaginal arteries for the inferior vesical arteries in the de. The venous plexuses are rectal, vesical, pudendal, ovarian, erine, and vaginal. The nerve-plexuses peculiar to the female are e uterine, ovarian, and vaginal.


966


A MANUAL OF ANATOMY


General Position of the Viscera. —The pelvic colon and rectum

situated as in the male pelvis. The bladder lies anteriorly, b situated immediately behind the bodies of the pubic bones, and urethra is very closely related to the anterior wall of the vagina, virgin uterus lies upon the superior surface of the bladder, and the hi ligaments extend from either side of it to the lateral wall of the pe The vagina leads from the lower end of the uterus, and in its outv course lies between the base of the bladder and the rectum.

Peritoneum. —The peritoneum is related to the pelvic colon rectum as in the male. On leaving the rectum at a point fully 3 in above the anus it passes to the posterior wall of the vagina, whi( covers for about its upper fourth. It then mounts upwards over posterior surface of the supravaginal portion of the cervix uteri and


Fig. 561. —Female Pelvic Viscera seen from Above.


Ureter


Rectum

Sacro-gen. Fold Infundib. Pelvic Lig.

Ovary Uterine Tube

Round Ligament


body of the uterus. On reaching the fundus it turns round to anterior surface, which it invests as low as the junction of the b and cervix. On leaving the viscus it passes to the upper part of the 1 of the bladder, whence it extends forwards over the superior surf which it covers as far as the apex. Its later course is as in the rr Along each lateral border of the bladder the peritoneum is refle< on to the lateral wall of the pelvis. Along either side of the uteri is reflected on to the lateral wall of the pelvis, and in this manner broad ligaments are formed. Between the rectum and the upper ] tion of the posterior wall of the vagina and supravaginal portion of cervix uteri the peritoneum forms a recess, called the recto-uterine po (pouch of Douglas), which corresponds to the recto-vesical pouch in male. The mouth of this pouch is bounded on either side by a semilr peritoneal fold, which extends from the front of the sacrum over the



THE ABDOMEN


967


the rectum to the cervix uteri. These folds are known as the rectorine folds (folds of Douglas) . Each fold contains a collection of fibrous i plain muscular tissues, connected on the one hand with the fibrous uctures in front of the lower part of the sacrum, and on the other

h the cervix uteri. They become continuous with each other over »back of the isthmus uteri (junction of body and cervix), and there »y give rise to a transverse ridge, called the torus uterinus. The to-uterine pouch is bounded in front by the upper part of the posterior


1st Sacral Vertebra


Uterine Tube


Fundus Uteri


Bladder


Parietal Peritoneum


1st Coccygeal Vertebra


Symphysis Pubis

Urethra

Anterior Wall of Vagina , ; , Anal Canal

Anterior Fornix | R ec to-uterine Pouch Posterior Fornix

Fig. 562. —Vertical Sagittal Section of the Female Pelvis.


ill of the vagina and the supravaginal portion of the cervix uteri, and hind by the rectum. In front of the uterus the peritoneum gives >e to a small recess, called the vesico-uterine pouch, the entrance to tiich is bounded laterally by two folds, called the vesico-uterine folds. 5 regards the bladder, the peritoneum forms for it false ligaments as the male—namely, one superior, two lateral, and two posterior, tie latter are simply the vesico-uterine folds, and may be regarded not ily as posterior ligaments of the bladder, but also as anterior ligaments the uterus.








968


A MANUAL OF ANATOMY


Pelvic Fascia. —The parietal pelvic fascia in the female is sim to the corresponding fascia in the male. The visceral pelvic fas however, is complicated by the interpolation of the vagina. On eit side of the pelvic viscera it divides into four laminae as follows: vesi which forms on either side the lateral pubo-prostatic ligament of bladder; vesico-vaginal , which passes between the bladder and vagina; recto-vaginal , which passes between the vagina and the rectr and rectal , which passes over the sides and posterior wall of the recti

Broad Ligaments of the Uterus. —These are also called the . vespertilionis , from their supposed resemblance to a bat’s wings. E; is an extensive fold of peritoneum composed of two layers, anterior c posterior, which pass between the side of the uterus and the late wall of the pelvis. The broad ligament has associated with it following important structures: (i) the uterine tube or oviduct, wh lies within the superior border of the ligament; (2) the ovary and ligament, which lie within a backward extension of the posterior la; of the broad ligament at a lower level than the uterine tube; (3) i ligamentum teres of the uterus, which lies within a forward project of the anterior layer of the broad ligament, also at a lower level tt the uterine tube; (4) the epoophoron, which lies within the ligam( between the ovary and the uterine tube; and (5) the paroophoron early life), which also lies within the ligament, medial to the epoophoi and near the uterus. The double fold of peritoneum attaching 1 anterior border of the ovary over its whole length to the back of 1 broad ligament forms a short mesentery for it, called the mesovariu which contains between its two layers the bloodvessels and nerves the ovary. The portion of the broad ligament which lies between 1 uterine tube and the ovary with its ligament is called the meso-salpi: It is somewhat falciform, and is narrow medially but broad lateral It is bounded above by the uterine tube, below by the ovary and ligament, medially by the uterus, and laterally by the ovarian limb and the suspensory ligament of the ovary.

Ligamentum Tere Uteri (Round Ligament). —This is a narrow, f band, about 5 inches long, which is attached to the upper part of t side of the uterus in front of, and a little below, the medial end of t uterine tube. It is composed of fibrous connective tissue, which m the uterus has an admixture of plain muscular fibres continuous w: those of the uterus. It lies within the anterior layer of the bro ligament, where it gives rise to a slight prominence. Its direction outwards, upwards, and forwards over the obliterated umbilical arh and pelvic brim to the deep inguinal ring, close to which it hooks rou the outer side of the inferior epigastric artery, and crosses the exteri iliac vessels from within outwards. Escaping by the deep inguii ring, it traverses the inguinal canal, and, emerging through the sup ficial inguinal ring, ends in the subcutaneous tissue of the labium maj For a short distance after entering the inguinal canal it is covered bj process of the peritoneum, which represents the processus vaginalis the male foetus. This process is at first tubular, and receives the na]


I


THE ABDOMEN


969


the vestige of processus vaginalis (canal of Nuck). It is usually, yever, obliterated in the adult, though it may remain pervious, ler which circumstances the condition known as hydrocele of the mentum teres may occur. A few muscular fibres may be found in it of the ligamentum teres in the inguinal canal, which are conious with the lower fibres of the internal oblique, and represent the master in the male.

The ligamentum teres is supplied by two arteries as follows: the mentous branch of the ovarian artery, which supplies it as far as inguinal canal; and the ligamentous branch of the inferior epigastric,


Fundus

Cavity of Body of Uterus i


Ligament of Ovary


Uterine Tube

,Epoophoron


Cavity of Cervix ~4

External Os. (Anterior Lip)


Ostium Abdominale

Appendix Vesiculosa


Ovary


Ligamentum Teres of Uterus Broad Ligament


Fig. 563. —The Uterus and its Appendages.

A, the uterus opened, and the right broad ligament (posterior view);

B, the os uteri externum.


ich supplies it beyond the deep inguinal ring, and corresponds to cremasteric artery in the male. The principal venous blood is irned by a ligamentous vein, which is a tributary of the ovarian xus.

The ligamentum teres uteri represents the gubernaculum testis in ■ male.

Ovaries.—The ovaries are two small flattened bodies, each of which within a backward extension of the posterior layer of the broad tfnent, with which it is connected by the mesovarium. The ovary derally compressed, and usually lies with its long axis almost vertical, inclining a little downwards and backwards, against the lateral










97°


A MANUAL OF ANATOMY


wall of the pelvis in a peritoneal depression called the ovarian ft It may, however, lie obliquely, and may even be shifted, near to uterus. In size it may be likened to the half of a small walnut average length being from i inch to if inches, its breadth about f i: and its thickness (from side to side) from \ to \ inch. Its ave: weight is about 2 drachms. It presents two surfaces, two borders, two extremities.

The surfaces are laterally disposed, and are called medial , rel; to the uterine tube, and lateral, related to the ovarian fossa, borders are anterior and posterior. The anterior or mesovarian bo is straight. Along it are attached the two layers of the mesovan and between these it presents a hilum for the passage of the bli vessels, nerves, and lymphatics. The posterior or free border is cor and lies in close relation to the ureter. The extremities are na: ends (poles), superior and inferior respectively. The superior is na: the tubal end, because the ovarian fimbria is attached to it or nea Connected with it there is also a fold of peritoneum, which pa upwards to join the peritoneum over the psoas major near the u] part of the external iliac vessels. This fold, which is termed the pensory ligament of the ovary, or the ovario-pelvic ligament, is < tinuous with the outer part of the broad ligament, and contains ovarian vessels and nerves. The inferior end is known as the ute end, and is connected with the superior angle of the uterus by a io cord, called the ligament of the ovary, or the ovario-uterine ligam The attachment of this ligament to the uterus is behind and a 1 below the medial end of the uterine tube.

The surface of the ovary is covered by modified peritoneum, < tinuous with the mesovarium, the only exception being along anterior border, where the hilum exists. The connective-tissue elen of this peritoneum is inseparably blended with the so-called tu albuginea of the ovary, and it is covered by an epithelium the cel] which present a striking contrast to those of the endothelial cove elsewhere. It is composed of short columnar cells, and imparts a so what dull appearance to the surface, which contrasts with the polis appearance elsewhere. The ovarian epithelium is the remains of germinal epithelium, from which the ovary is developed, and at circumference of the organ it passes abruptly into the endothelial < of the adjacent peritoneum. Prior to puberty the surface of the o\ is smooth, but after that period it gradually assumes a pitted scarred appearance, which is due to the periodical escape of the from the vesicular ovarian follicles.

Descent of the Ovary. —The ovary, like the testis, originally lies in the lun region of the body-cavity by the side of the vertebral column. At this pe the inguinal fold, as stated, extends from the caudal end of the ovary to inguinal region, where it traverses the inguinal canal, and terminates within labium majus. As the ligament descends it becomes connected, as stated, ' the para-mesonephric duct at the level where this duct fuses with its fello’' form the uterus; the portion above the point of fusion becomes the ligamer the ovary, the portion below the ligamentum teres. About the third mont


THE ABDOMEN


971


i-uterine life the ovary begins to descend towards the brim of the pelvis, ing arrived at the pelvic brim, it remains there for some time, and is still lat level at the period of birth. At a later period it descends into the pelvic ty as a rule, and assumes its normal position within a backward extension of broad ligament of the uterus.

rwo factors are probably concerned in the descent of the ovary—namely,

he shortening of that part of the inguinal fold which extends from the ovary he side of the uterus close to the medial end of the uterine tube; and (2) the tion exercised by the fusion of the two para-mesonephric ducts to form the us and vagina.

(\.s each ovary descends, its mesovarium is taken along with it. This mesoum is intimately connected with the uro-genital fold, which contains the onephric and para-mesonephric ducts; and the uro-genital fold in turn is bined with the mesonephric ‘ mesentery ’ or ligament. The vestigial portions he mesonephros in the female are therefore carried down along with the sending ovary, these vestigial portions representing (1) the so-called duct of epoophoron or duct of Gartner, (2) the epoophoron, and (3) the paroophoThe combined mesovarium, uro-genital fold, and mesonephric ‘ mesentery ’ igament of each side become continuous medianly, and form one continuous it. Within this sheet the uterus is formed by the fusion of the two paraonephric ducts; each lateral part of the sheet constitutes the broad ligament be uterus.

Abnormal Positions of the Ovary. —(1) The ovary, in its original descent, r pass into the inguinal canal, and even into the labium majus; (2) it may 3 through the femoral ring into the femoral canal, and lie over the saphenous ning, where it may simulate a femoral hernia; (3) an ovary, when enlarged, / become prolapsed, and pass downwards and inwards behind the uterus ) the recto-uterine pouch, where it may be palpated through the posterior lix of the vagina.

For the structure and development of the ovary, see p. 980 et seq. Epoophoron.—The epoophoron is situated in that portion of the so-salpinx which lies between the ovary and the uterine tube. It is nposed of a number of small blind tubules, lined with epithelium, ich converge towards the ovary, but do not meet. Their tubal ends united by a longitudinal tube, which lies parallel with and a little ow the uterine tube, the duct of the epoophoron.

Paroophoron.—The paroophoron is situated in that part of the so-salpinx which lies between the ligament of the ovary and the !rine tube, where it is placed near the uterus. It is composed of a 1 minute blind tortuous tubules, which usually become shortly after th invisible to the naked eye.

For the development of the epoophoron and paroophoron, see

987. _

Uterine Tubes (Fallopian Tubes).—The uterine tubes, right and left, ve to convey the ova, after their escape from the vesicular ovarian Licles, into the cavity of the uterus. They are, therefore, functionally ' ducts of the ovaries, and are hence spoken of as the oviducts. Each is contained within the superior border of the broad ligament, except its extreme inner end, where the tube is embedded in the uterine wall, is fully 4 inches in length. Proceeding from the uterus, it passes at d horizontally outwards for about 1 inch towards the lower or uterine 1 01 the ovary. It then ascends vertically for a short distance upon 5 lateral wall of the pelvis, where it lies medial to the anterior or


97 2


A MANUAL OF ANATOMY


attached border of the ovary. Having arrived at the upper or ti end, it arches backwards and descends along the posterior convex bo and adjacent portion of the medial surface of the ovary. Each ute tube is divided into the following parts: pars uterina, isthmus, ampi neck, and corpus fimbria turn; and each has two openings, ost uterinum and ostium abdominale.

The pars uterina is the limited portion which is contained wi the uterine wall at the superior angle, and it presents the ost uterinum, which is about i millimetre in diameter. The isth succeeds to the pars uterina, and represents about one-third of tube. It is straight, round, and firm to the touch, due to the dominance of circular muscular fibres in this portion. Its diam is about 2\ millimetres. The ampulla succeeds to the isthmus, forms rather more than half of the tube. It is larger than theisthr less resistant (being chiefly mucous in structure), and tortuous, diameter gradually increases in the distal direction, the average b about 7 millimetres. The ampulla at its outer end becomes constri( to form the neck, which presents the ostium abdominale, opening the pelvic cavity, its diameter being about 2 millimetres. It is in situation where the general cavity of the peritoneum in the fema] continuous with the lumen of the uterine tube, and through it with cavity of the uterus and vagina. Beyond the neck the tube expa in the form of a funnel, called the infundibulum, near the centr which the ostium abdominale is situated. The circumference of infundibulum is broken up into a number of irregular fringes, ca fimbrice, and the outer end of the tube is hence called the corpus fiml turn. The larger fimbriae are broken up into smaller filiform proces The outer surfaces of the fimbriae, which look into the pelvic cavity, covered by peritoneum, but the inner surfaces, which look into infundibulum, are covered by mucous membrane continuous with 1 of the uterine tube. At the free margins of the fimbriae the peritone with its endothelial cells, becomes continuous with the mucous m brane, which is covered by ciliated columnar epithelium. One of fimbriae, which is larger and longer than the others, is called the ova\ fimbria, and is either directly connected with the upper or tubal of the ovary, or indirectly by means of a delicate fibrous band deri from and continuous with the broad ligament. This fimbria pres< a longitudinal furrow, which serves as a channel of communica between the ostium abdominale and the ovary.

For the structure and development of the uterine tubes, see p. <

Uterus.—The uterus is a hollow muscular organ, which receive: its superior angles the uterine tubes, and opens below through the up part of the anterior wall of the vagina. Through the uterine tube receives the ova at periodical intervals, and when an ovum becoi impregnated the uterus retains it during development, and therea expels the foetus through the vagina. The virgin uterus lies upon superior surface of the bladder, and is usually inclined to the righ the middle line. Above it there are a portion of the pelvic colon


THE ABDOMEN


973


jually a few coils of the ileum. At its lower end is the vagina, and le broad ligament stretches from either side. It is somewhat pyriform, le wide end being directed upwards and forwards, and is flattened


om before backwards. It is -m and resistant to the touch 1 account of its very thick uscular walls. Its average ngth is 3 inches, the breadth the upper part being 2 inches, id the thickness i inch. The gan is divided into a fundus, )dy, and cervix.

The fundus is that portion hich lies above the level of a le connecting the superior igles, where the uterine tubes iss through the uterine wall, is convex from side to side, d also from before backwards, le lateral borders of the erus are sloped downwards d inwards, and at the junction the upper two-thirds and ver third of the organ there a slight constriction or convity, called the isthmus, which also present in front and hind, and is most conspicuous early life. The part between s fundus and the isthmus is 3 body, and the part below s isthmus is the cervix.


Fig. 564. —Side View of Uterus and Upper Part of Vagina, to show Reflections of Peritoneum.


F, uterine end of tube; O, L, ovarian and round ligament; V, between the reflections of layers of broad ligament, marks region where branches of uterine artery enter the organ; SUS, suspensory ligament (Mackenrodt) ; UV, uterovesical fold; R, rectal fold; T, torus uterinus.


The body, which is 2 inches long, is triangular and presents two ooth surfaces, anterior and posterior, and two lateral borders. The terior or vesical surface, which has an inclination downwards, is flat slightly convex. The posterior or rectal surface, which has an inlation upwards, is very markedly convex. This difference in the flour of the two surfaces permits of their easy identification. Each wal border extends from the superior angle to the isthmus, and sloped downwards and inwards. The superior angles are situated the point of entrance of the uterine tubes, and correspond with ' portions of the uterus which are elongated into cornua in some mals.

The cervix, which measures 1 inch in length, is cylindrical, and rower than the body. It is received into the upper part of the erior wall of the vagina, the walls of which are attached to it in h a manner as to divide it into two portions—supravaginal and ravaginal. The posterior wall of the vagina extends higher upon the



974


A MANUAL OF ANATOMY


cervix behind than the anterior wall does in front. The antei surface of the supravaginal portion, which is about J inch in exte is related to the base of the bladder, with the intervention of so loose cellular tissue. The posterior surface of the supravaginal porti which is about J inch in extent, forms a part of the anterior wal] the recto-uterine pouch, and is crossed transversely by the to uterinus. At the lower end of the intravaginal portion, where cervix is slightly protuberant, there is an opening, called the exter os of uterus, through which the cavity of the cervix communica with that of the vagina. This opening is also known as the os tinea, cause it is supposed to resemble the mouth of the tench fish, on accoi of its lips being of unequal size. In early life this opening is circu but later, in the virgin, it assumes the form of a transverse slitab X2 inch long. It is bounded by two lips, anterior and posterior, wh in the virgin are smooth, but in multipart they are often more or ] fissured, especially the posterior lip. The anterior lip is thick, rou and short, whilst the posterior is thin, sharp, and long. The ante] lip descends lower into the vagina than the posterior, by reason of oblique manner in which the cervix uteri passes into the canal. I the anterior lip which first meets the finger in making vaginal exami tions. The greater length of the posterior lip is due to the fact that posterior wall of the vagina extends higher on the back of the cer than the anterior wall does in front. The external os is directed do) wards and backwards, towards the posterior wall of the vagina, i being due to the oblique position of the cervix.

Surrounding the vaginal portion of the cervix there is a vaul recess, which is divided into anterior, posterior, and lateral fornit In the region of the lateral fornix the ureter is situated f inch from cervix.

General Relations of the Uterus.—The anterior surface of the be rests upon the superior surface of the bladder, and the anterior surf of the supravaginal portion of the cervix is related to the base of bladder. The lateral relations are the uterine tubes, ligamenta tei ligaments of the ovaries, broad ligaments, and a certain amount adipose tissue, containing large bloodvessels, which lies upon either s of the cervix, and extends upwards over the lateral border between layers of the broad ligament. This collection is known as the pa metrium. The posterior surface of the body is related to the recti and the posterior surface of the supravaginal portion of the cer forms a part of the anterior boundary of the recto-uterine pouch.

Peritoneal Relations.—The following parts of the uterus are cove by peritoneum: the supravaginal portion of the cervix posterio: the posterior surface of the body, the fundus, and the anterior surf of the body as low as the front of the cervix. The following parts free from peritoneal covering: the intravaginal portion of the cen the supravaginal portion of the cervix anteriorly, and a narrow st along each lateral border where the two layers of peritoneum pass i to form the broad ligament. The uterine peritoneal folds are as folio


THE ABDOMEN


975


3 utero-vesical, sometimes called the anterior uterine ligaments, but

y may also be regarded as the posterior false ligaments of the bladder; recto-uterine folds, with the torus uterinus; the ligaments of the iry, the ligamentum teres on each side, and the broad ligaments. Position of the Uterus. —The virgin uterus occupies a position of

eflexion and anteversion, assuming the bladder and rectum to be pty. In speaking of the uterus as being anteflexed it is to be underod that the body of the organ is bent forwards at the isthmus in

h a manner that it forms with the cervix an angle which is open eriorly. This is brought about in the following manner the cervix

Fundus


Cavity of Body of Uterus


Ligament of Ovary


Cavity of Cervix


External Os of Uterus (Anterior Lip)


Uterine Tube

v Epoophoron


Ostium Abdominale

' - Appendix Vesiculosa


Ovary


Ligamentum Teres of Uterus Broad Ligament


Fig. 565. —The Uterus and its Appendages.

A, the uterus opened, and the right broad ligament (posterior view);

B, the external os of uterus.


ri is more fixed than the body, from its connection with the vaginal Us and base of the bladder; and the cervix is less yielding than the ly. In speaking of anteversion of the uterus it is to be understood it the entire uterus is inclined forwards, so that its long axis forms angle with the longitudinal axis of the trunk. The anterior surface 5 therefore a downward inclination towards the superior surface of

bladder, and the posterior surface has an upward inclination, and supports a portion of the pelvic colon and a few coils of the ileum. ien the bladder is distended, the position of the uterus becomes ered. The organ is raised along with the distended bladder, the eflexion and anteversion become less, and the uterus may even assume a vertical position. Any coils of the ileum lying in con with its posterior surface, as well as the pelvic colon, would be displa and the organ would come to be closely related to the rectum.

Interior of the Uterus. —The interior is divided into two portior the cavity of the body and the cervical canal. The cavity of the l is very small compared with the thickness of the uterine walls, an triangular, with the base directed upwards towards the fundus, three sides are convex towards the cavity, and its anterior and poste walls are in contact. In the vicinity of each superior angle it narrc and gradually tapers to the medial end of the"uterine tube, with


Fig. 566. —Bladder, Vagina, and Rectum, exposed from the Right, show Peritoneal Reflections and Visceral Relations.

lumen of which it is continuous. Interiorly the cavity also becor narrow, and at the junction of the body and cervix it ends in a circu opening, called the internal os of uterus, which is smaller than external os. Through this opening it becomes continuous with cavity of the cervix. The canal of cervix is spindle-shaped, being wi< at the centre than at either end. It is somewhat flattened from bef< backwards, and is continuous above with the cavity of the be through the internal os, and below with the cavity of the vagina thror the external os. Its mucous membrane presents two longitude ridges, anterior and posterior, from each of which a number of ru id in an upward and outward direction, the appearance thus prod being known as the arbor vita. The length of the cavity of the is is 2 \ inches, the difference between its length and that of the is, as measured externally, being due to the thickness of the fundus to the fact that the external os lies at the centre of a depression, ’terus at Birth. —At birth the neck of the uterus is larger than Dody, and there is no fundus. At each superior angle it tapers much, and resembles somewhat a uterus bicornis. The arbor extends all along the interior.

arieties. —These are as follows: (i) uterus bicornis; (2) uterus unicornis; 3) double uterus. These variations are due to the partial or complete perlce of foetal conditions.

'or the structure and development of the uterus, see pp. 983

V

r agina. —This is a musculo-membranous passage which extends t the cervix uteri to the vulva. It is from 3 to 3J inches long,

3 inches along the anterior wall and 3-J inches along the posterior. slightly curved, and its direction is downwards and forwards, ixis forms an obtuse angle with that of the uterus (ioo° to no°). re erect posture it forms with the horizontal an angle of about 6o°. iriorly it is closely connected with the cervix uteri, the posterior rising higher than the anterior. It is rather narrower at either than at the centre, the lower end being the narrowest part of the age. The walls are anterior and posterior, and they are in contact, ransverse section the vagina appears as an H-shaped fissure at its

r end, as a transverse fissure at the centre, while at its upper end it ents a lumen which is almost circular.

delations — Anterior .—The base of the bladder and the urethra. erior .—From above downwards there are the recto-vaginal pouch 1 short distance, the rectum, with the intervention of the rectonal lamina of the visceral pelvic fascia, and the anal canal, from

h it is separated by the perineal body. The posterior wall is ired by peritoneum over about its upper fourth. Lateral .—The er at the upper end for a short distance, and the levatores ani cles.

rhe vagina passes through the perineal membrane, and its lower has a bulb of the vestibule on either side, with the bulbo-spongiosus ounding the external orifice. When the finger is passed into the terior fornix, which is the recess between the posterior lip of the irnal os of uterus and the posterior wall of the vagina, the rectoinal pouch can be palpated and a few coils of the ileum, or a prosed ovary, may be felt in it. The base of the bladder may be paled through the anterior fornix, and the urethra through the interior i of the vagina lower down. In the lateral fornices the ureters may be felt.

For the structure and development of the vagina, see p. 986. Bladder. —The base is directed backwards, and is related to the it of the supravaginal portion of the cervix uteri and a portion of the anterior wall of the vagina, the vesico-uterine pouch of the peritone intervening. The superior surface is in contact with the ante surface of the body of the uterus. The false ligaments formed by peritoneum are at least three in number—namely, one superior ; two lateral. The peritoneal folds on either side of the vesico-ute] pouch are usually regarded as the anterior uterine ligaments, but t may also be looked upon as the posterior false ligaments of the blad< The true ligaments are similar in both sexes.

Ureters. —Each ureter lies for a short distance on the side of cervix uteri and upper part of the wall of the vagina, being cros

antero-superiorly near the


vix from without inwards the uterine artery.

Urethra. — The urethra very closely related to the terior wall of the vagina.


length is ij inches, and


transverse diameter is ab J inch, the narrowest part be


at the external orifice, direction of the canal is do 1 wards and forwards, and walls are anterior and poster these being in contact exc during micturition. In course it passes between two layers of the perineal mi brane, where it is embraced the sphincter urethrae mus The canal is capable of c siderable distension, and m under anaesthetics, admit index finger. The external 1 fice of urethra is situated in middle line immediately in fr of the external orifice of vagina, and is placed on a sli prominence, the margins which are somewhat irregul;

For the structure and development of the urethra, see p. 987. Rectum—Relations — Anterior .—The uterus and vagina, the rec vaginal pouch intervening for a short distance in the vicinity of cervix uteri. Posterior .—As in the male.

Anal Canal. —This is separated from the vagina by the perir body.

Ovarian Artery in the Pelvis. —This vessel, which arises from abdominal aorta about 1 inch below the renal artery, enters the pe by crossing the commencement of the external iliac. It then pa*


Fig. 567. —Diagram to show Lateral Relations of Vagina, and of Ureter, etc.


in the broad ligament of the uterus, where it is very tortuous, and ranches to the ovary enter that organ through the hilum on the rior border without piercing the peritoneum. Besides supplying ovary, the vessel furnishes the following branches: uterine to the ns, near the superior angle, where it anastomoses with branches of iterine artery from the internal iliac; tubal to the uterine tube; and nentous to the ligamentum teres of the uterus, which it accompanies ir as the inguinal canal.

'he ovarian vein of each side originates as two vessels in the ovarian ampiniform plexus, which lies within the broad ligament. This us receives the veins which emerge through the hilum of the ovary,


Fig. 568. —The Ovarian, Uterine, and Vaginal Arteries (Posterior View) (after Hyrtl).


fell as tributaries from the uterine tube and the ligamentum teres he uterus, and it communicates freely with the uterine plexus, two ovarian veins, having emerged from the ovarian plexus, leave pelvis, and soon join to form a single vein, that of the right side ling into the inferior vena cava, and that of the left side into the renal vein.

Uterine Artery.— This vessel is derived from the anterior division tie internal iliac artery. It is directed downwards and inwards to side of the cervix uteri, near which it crosses the ureter. On reaching the cervix it turns upwards along the lateral border of the body in Ty tortuous manner, lying between the two layers of the broad ligament. As it descends it gives off tortuous branches to the front a back of the body, and near the inner end of the uterine tube it anas moses freely with the uterine branch of the ovarian artery. Along 1 side of the body it also gives offsets to the ligamentum teres ut< ligament of the ovary, and uterine tube. At the cervix the uter artery furnishes two branches—cervical and vaginal. The cervi branch supplies offsets to the cervix. One of these, called the coron> artery , divides into two branches, which with their fellows of the < posite side form an arterial circle around the cervix. The vagi branch divides into two, anterior and posterior, which descend in middle line of the anterior and posterior walls of the vagina, where tl anastomose with branches of the vaginal arteries.

The uterine veins, which are destitute of valves, form a copi< plexus within the broad ligament close to the uterus, where it is e bedded in the parametrium. The blood from the lower part of t plexus is conveyed away by two uterine veins, which are tributaries the internal iliac vein. A large proportion of the blood, howe\ passes from the upper part of the plexus into the ovarian plexus. 1 uterine plexus communicates below with the vaginal plexus.

Vaginal Artery. —This vessel, which usually replaces the infer vesical of the male, arises from the anterior division of the inter iliac, occasionally in common with the uterine or the middle rec artery. It passes downwards and inwards to the wall of the vagi where it divides into branches which anastomose with their felk of the opposite side, the vaginal branches of the uterine arteries, c towards the lower end of the vagina with branches of the inter pudendal. Along the anterior and posterior walls, in the median li an arterial chain is constructed by the vaginal arteries and the vagi branches of the uterine arteries, thus forming the vessels known as azygos arteries of the vagina. The vaginal artery also furnishes branc. to the bladder, rectum, and bulb of the vestibule.

The veins of the vagina form a rich plexus in the muscular cc which is more copious towards the lower end. They communic above with the uterine plexus, in front with the pudendal pie: around the urethra, behind with the rectal plexus, and below with veins of the bulb of the vestibule. The vaginal vein leaves the up part of the vaginal plexus and opens into the internal iliac vein.


The Structure of the Special Viscera of the Female Pel 1

The Ovaries.

The ovary is covered by a layer of short columnar epithelial c< These are the remains of the germinal epithelium from which organ is developed, and they rest upon a delicate connective-tk membrane, which is blended with the so-called tunica albugir Interposed between the columnar cells there are a few spheroidal c of larger size, which are primordial ova. The connective-tissue m


e is continuous with the peritoneum, which forms the mesovarium y the margins of the hilum, and is covered by endothelium. Within membrane, and blended with it, there is a continuous covering, isting of fibrous connective tissue, which is called the tunica albu1, from its supposed resemblance to the tunica albuginea of the s. It is, however, really a condensation of the ovarian stroma at surface. This stroma pervades the interior of the ovary, and is Dosed of fibrous connective tissue, which is richly provided with lie-shaped cells and elastic tissue. There are also a few plain

ular fibres in the deeper part of the ovary close to the hilum. The lie-shaped cells are regarded by some authorities as muscular fibre, but they probably belong to the connective tissue of the stroma, stroma is freely permeated by bloodvessels, and contains the nilar ovarian follicles. Immediately within the surface there is a r of the stroma which presents a granular appearance, especially in ig persons, due to the presence of an immense number of ovarian


Fig. 569. — Section of the Ovary, showing its Minute Structure.


les, with their contained ova, in an early stage. This part of the y is called the cortex, the remainder being known as the medulla. ig more deeply in the stroma there is another set of ovarian follicles, numerous but of larger size, these being in a more advanced stage, more deeply there is another and less numerous set of follicles, of larger size, which are almost in a state of maturity. When these sr have attained full development they pass towards the surface, re they may sometimes be seen as clear follicles causing slight proions. When fully developed, they attain a diameter of about ich. At periodical intervals one or more of these mature follicles ture, this being accompanied by the discharge of a fluid—the liquor culi—and the simultaneous escape of the contained ovum or ova. ir the discharge of its contents the follicle becomes filled with blood and cellular tissue, and assumes a yellow colour. It is then known a corpus luteum. This undergoes atrophy in the virgin, and, assumi a white colour, is known as a corpus albicans.

Structure of the Vesicular Ovarian Follicles (Graafian Follicles). The smallest follicles near the surface, which are about inch diameter, consist of a single investing layer of flattened cells clos< embracing the contained ovum. It is computed that the ovaries 0 child at birth contain as many as 70,000 of these follicles. In follic a little more advanced the investing epithelium becomes column and is arranged in two layers—outer and inner, the latter surroundi the ovum. In more mature follicles fluid, called the liquor follioi accumulates between the outer and inner cellular layers, except at 1 point where the ovum lies. The outer layer is then known as i membrana granulosa, and the inner as the discus proligerus. The c( of these two layers became continuous at the part* where the liqi folliculi is absent, so that in this manner the ovum is anchored to c point of the wall of the follicle. In the most mature follicles the liqi folliculi has increased in amount, and the cells of the membrana grai losa and discus proligerus have multiplied so as to form several stra Each of these follicles has a distinct wall, called the theca folliculi , wk is formed by a condensation of the surrounding stroma, and in whi two layers can be recognized—an outer fibrous and an inner vascul There is usually only one ovum in each follicle.

For structure of the ovum, see p. 14.

Blood-supply of the Ovary. —The ovary receives its blood from t ovarian artery.

Nerves. —These come from the ovarian sympathetic plexus, wh derives its fibres from the renal and aortic plexuses, and accompan the ovarian artery.

Lymphatics. —The lymphatic vessels of the ovary accompany 1 ovarian bloodvessels, and terminate in the juxta-aortic glands on eitl side. They are joined by most of the lymphatics of the body of 1 uterus and by those of the uterine tube.

The ovaries represent the testes in the male, and they have b< called the testes muliebres.

Ligament of the Ovary. —This is composed of plain muscular 3 fibrous tissues, the former being continuous with the muscular tis of the uterus. It derives its blood-supply from the ovarian art' and represents the upper part of the gubernaculum testis in the mj foetus.

Structure of the Uterine Tubes.

The wall of the uterine tube is composed of four coats—sere muscular, submucous, and mucous. The serous coat is formed the peritoneum. The muscular coat is composed of plain mused tissue arranged as an outer longitudinal and inner circular layer, latter being the thicker. The submucous coat is areolar in structi The mucous coat is continuous with that of the uterus on the one has with the peritoneum on the other at the margins of the fimbriae. 3 thrown into longitudinal folds, which are simple in the isthmus, complex in the ampulla, where they are beset with secondary folds, communicate in such a manner as to give rise to alveolar spaces, 3 imparting an almost glandular appearance to the coat. In trans>e section the tube presents a branched lumen, which is nearly filled the leaf-like processes formed by the mucous folds. The mucous nbrane is covered by ciliated columnar epithelium, which, at the

margins of the fimbriae, passes into the endothelium of the perieum. Blood-supply. —The ovarian and uterine arteries.


Fig. 570. —Transverse Section of the Uterine Tube (magnified).

Nerves. —These are derived from the ovarian and uterine sympadic plexuses.

Lymphatics. —These pass to the median lumbar glands along with )se of the ovary and upper part of the body of the uterus.

Structure of the Uterus.

The wall of the uterus consists of three coats—serous, muscular, d mucous—there being no submucous coat.

The serous coat is formed by the peritoneum, already described. The muscular coat is composed of plain muscular tissue, with an mixture of areolar tissue, and it imparts great thickness to the wall. ie muscular tissue is disposed in three strata- outer, middle, and ler. The outer stratum is thin, and its fibres are disposed longitudinally over the front and back of the organ, becoming continuous with ( another by turning over the fundus. Those nearest the lateral bord incline outwards, and are prolonged into the ligamenta teres, uter tubes, and ligaments of the ovaries. Some from the back of the sup vaginal portion of the cervix are prolonged into the recto-uterine fol The middle stratum is very thick, and is composed of fibres which int lace in a complex manner over the body, but in the neck they ; arranged circularly. The bloodvessels and nerves are freely int spersed throughout this layer. The inner stratum , which is also v<


Fm. 571. —Upper Figure, Diagram to show Composition of Uterine Wa:

M, muscular wall. The lower sections show on the left a piece of premenstr mucosa; on the right one from an early pregnancy. The stroma-cells ; enlarging, and in the last specimen are very evident as decidual cells.

thick, has its fibres disposed longitudinally in the cervix. As th ascend over the body they become oblique, and at the superior ang they run circularly. The uterine glands project into this stratuj and it contains a free admixture of areolar tissue. It is right to menti that the inner stratum is regarded as a very much thickened muscula mucosae, according to which view it would form a part of the muco coat (Williams).

The mucous membrane of the cavity of the body is smooth, and sc in consistence, and is covered by ciliated columnar epithelium. Itj



t with a number of openings, which are the mouths of the uterine tricular glands. These are simple tubular glands, which extend somewhat convoluted manner through the entire thickness of the ous coat, and project by their deep blind ends into the inner cular stratum, there being no submucous coat. Each gland is posed of a basement membrane, which is lined with ciliated mnar epithelium, continuous with that of the cavity of the body, h has a distinct lumen, except at its deep end, where it is filled l cells. The mucous membrane of the canal of cervix is of firmer dstence than that of the cavity of the body, and, as has been stated, resents the appearance known as the arbor vitae. It is provided 1 papillae, and is covered olumnar epithelium, except - the os externum, where epithelium is of the stratisquamous variety, like that sring the intravaginal porof the cervix and lining vagina. On the summits he rugae the columnar cells ciliated, but in the furrows veen them they are devoid cilia. The mucous mem(ie is freely provided with smose glands, which in the >er part of the cervix are d with columnar cells, and he lower part with cubical s. In both regions the s are non-ciliated. The ids in the lower part of cervix have each a large ten, and they secrete a very acious mucus during pregicy, which in the later ges of that period plugs the external os of uterus.

In addition to these glands clear vesicles of a yellowish colour, called ovula Nabothi, may be seen in the mucous membrane between the

ae of the arbor vitae, which are supposed to result from the blockage some of the racemose glands.

Blood-supply. —The uterus is supplied with blood by the uterine eries, and the uterine branches of the ovarian arteries.

Nerves.— The chief nerves are derived from the uterine sympaitic plexus, which is an offshoot from the pelvic plexus, and accomlies the uterine artery. It is to be noted that the pelvic plexus itains spinal fibres derived from the third and fourth sacral nerves metimes also the second), and from the upper two or three lumbar 'ves, as in the case of the bladder and rectum. The uterus also receives sympathetic fibres from the ovarian plexus, which is deri from the renal and aortic plexuses.


Fig. 572. — Scheme of the Lymphatic Drainage of the Uterus (after Cuneo et Marcille).



Lymphatics—Cervix Uteri. —The lymphatic vessels of the ce: have a threefold destination—namely, (i) the middle chain of external iliac glands, (2) the internal iliac glands , and (3) the inner gt of the common iliac glands.

Body. —(1) Most of the lymphatics of the body of the uterus the lymphatics of the ovary, and pass to the juxta-aortic glands. (2 few lymphatics pass to the middle chain of the external iliac gla: (3) Some lymphatics accompany the ligamentum teres of the ute and terminate in the superficial inguinal glands.

The lymphatics of the cervix communicate freely with those the body and with those of the upper part of the vagina.

Structure of the Vagina.

The wall of the vagina is composed of three coats—fibrous, n cular, and mucous.

The fibrous coat is composed of dense connective tissue.

The muscular coat consists of plain muscular tissue arranged an outer longitudinal and inner circular layer, both being closely c nected. Embedded in this coat there is a network of anastomos veins, representing erectile tissue, which is well developed round lower part of the passage. The plain muscular coat is replaced at external orifice by the striated bulbo-spongiosus muscle.

The mucous membrane is covered by stratified squamous epithelii and is provided with papillae. In the upper part of the passage it c tains mucous glands. Along the middle line of the anterior and poste walls it presents a ridge, these ridges being called the columns of vagina, or columnce rugarum. Passing off from them at right anj there are, in the virgin, numerous transverse rugae, these appearar being well marked in the lower part of the passage and absent in upper part.

Blood-supply. —The vagina is supplied with blood by the vagi arteries, the vaginal branches of the uterine arteries, and branches the internal pudendal arteries.

Nerves. —These are derived from the vaginal sympathetic pie: of each side, which is an offshoot from the pelvic plexus.

Lymphatics. —The lymphatic vessels are disposed in two set superior and inferior. The superior lymphatics come from about upper two-thirds of the vagina, and they pass to (1) the middle ch of the external iliac glands, and (2) the internal iliac glands on eit side. The inferior lymphatics come from about the lower third, ; include those from the vaginal surface of the hymen; they pass the inner group of the common iliac glands. The lymphatics fi the perineal surface of the hymen pass to the superficial ingu\ glands.

The superior and inferior vaginal lymphatics communicate from one another; the superior lymphatics communicate with those Le cervix uteri, and the inferior set communicate with those of the a.


Development of the Uterine Tubes, Uterus, and Vagina.

he uterine tubes, uterus, and vagina are developed from the para-mesonephric i, as described on pp. 101 and 102.

he two para-mesonephric ducts have been seen to meet and fuse into a single in the transverse pelvic ridge of mesoderm, the single tube passing to the ,1 wall of the uro-genital sinus and lying in the central thickened part of the verse ridge, which is termed the genital cord. The fused tubes within ord make the mucous lining of the uterus and vagina, the thick mesoderm e cord forming the walls of these parts ; the lateral portions of the transridge become the central parts of the broad ligament on each side of the is.

he transverse ridge is continuous on each side with the mesonephric ridge, ls, in fact, to be considered as made by the continuation of each ridge into elvis, where it meets its fellow of the other side. Hence the para-mesonephric 5, which are in the free edges of the mesonephric ridges, are also in the free 5 of the transverse ridge on each side of the central thickened ‘ cord ’; when equalities of growth-rate the ducts become altogether intrapelvic in position, necessarily lie in the free edge of the broad ligament on each side as the Qe tubes. Their fimbria begin to be apparent in the second month, are

r marked in the third month, and grow slowly after this. Accessory abnal ostia are sometimes found in the embryo, and are well known to occur e adult. The dilatations of the tubes appear during the later foetal months, ter birth. The narrowed uterine ends are due to the inclusion of these ends le mesodermal thickening that forms the muscular uterine wall. This gening begins in the third month, and not only takes in the ends of the tubes, includes also the attachment to these of the inguinal folds, thus leading to livision of each of these into ligamentum teres and ligament of ovary. In the

h month the vaginal lumen is blocked by solid epithelial masses; these break 1 centrally in the sixth month, and the lumen is re-established.

'he remnants of the mesonephric duct and its associated tubules, being among structures included within the mesonephric ridge, find their way into the d ligament with the para-mesonephric ducts as growth proceeds. The mephric duct becomes the duct of the epoophoron, and the tubules form the igial remnants known as the paroophoron and epoophoron; it is probable the ‘ appendix vesiculosa ’ also belongs to this series, but some maintain that a persisting remnant of the pronephric system.

"he abnormal condition of the uterus known as uterus bicornis is brought it by the fact that the two para-mesonephric ducts have united at a more erior (caudal) level than they usually do. The condition known as uterus ornis is due to imperfect development of one or other para-mesonephric duct, xtremely rare cases the para-mesonephric ducts fail to unite, and by opening pendently into the uro-genital sinus they give rise to a double uterus and 'uble vagina.


Structure of the Urethra.

The wall of the urethra is composed of three coats—muscular, 'tile, and mucous. The muscular coat, which is continuous with t of the bladder, is composed of plain muscular tissue arranged as outer circular and an inner longitudinal layer. The circular fibres well developed, especially at the upper end, where they partake tewhat of the nature of a sphincter muscle. Superficial to the circular fibres the urethra, as it lies between the two layers of 1 perineal membrane, is embraced by the striated fibres of the sphinc urethras. The erectile coat is composed of a rich plexus of veins, si ported and pervaded by areolar and elastic tissues. This plexus continuous above with that around the neck of the bladder. 1 mucous coat is covered by transitional epithelium in its upper pa and stratified squamous epithelium in its lower part. It is provic with papillae, and is thrown into longitudinal folds, which are tempore above, but permanent below. One fold, situated on the posterior w; is larger than the others, and is known as the crest. The mucous me brane is furnished with tubular mucous glands, and between t permanent folds in the lower part there are crypts or lacunae.

Lymphatics. —The lymphatic vessels of the female urethra join th< of the bladder, which pass to the external iliac , internal iliac , and comn, iliac glands.

Development of the Urethra.— The female urethra is developed from ventral or uro-genital compartment of the cloaca, caudal to that part wh gives rise to the bladder. It represents the prostatic portion of the male uret] as low as the prostatic utricle.

The Articulations of the Pelvis.

Lumbo-sacral Articulation. —The union between the fifth lmnt vertebra and the base of the sacrum is effected by means of the folio ing ligaments: an intervertebral disc, prolongations of the anter and posterior longitudinal ligaments of the bodies of the verteb above, capsular ligaments and synovial membranes for the articu processes, ligamenta flava for the laminae, and interspinous and sup: spinous ligaments for the spinous processes. These are similar to i corresponding ligaments above the level of the fifth lumbar verteb The articulation between the bodies of the fifth lumbar and the fb sacral vertebrae belongs to the class of secondary cartilaginous join and the joints between the articular processes belong to the class synovial joints, and the subdivision plane joints. In addition to t foregoing ligaments there are two special ligaments, called luml sacral and ilio-lumbar. The lumbo-sacral ligament at either si extends from the lower aspect of the transverse process of the fii lumbar vertebra anteriorly to the upper surface of the ala of the sacn at its anterior and outer part close to the sacro-iliac articulation. II somewhat fan-shaped, and corresponds to the intertransverse ligamei of the lumbar vertebrae and the superior costo-transverse ligaments the thoracic region. The ilio-lumbar ligament extends from the of the transverse process of the fifth lumbar vertebra to the inner of the iliac crest, where it is attached for about 2 inches above i back part of the iliac fossa. It is triangular, and its direction is oi wards and slightly backwards. It is closely associated with the lov part of the anterior layer of the lumbar fascia.

Arterial Supply. —Ilio-lumbar and superior lateral sacral arteries


Nerve-supply .— Fourth and fifth lumbar nerves, and sympathetic ients.

Movements. —Flexion, extension, and lateral movements between opposed bodies, and gliding and rotation between the articular esses.

acro-coccygeal Articulation.—This belongs to the class of secondary laginous joints. The bony elements are the fifth sacral and first ygeal vertebrae. The opposed surfaces are transversely oval, and separated by an intervertebral disc, unless in advanced life, when flosis takes place, this occurrence being earlier and more frequent le male than in the female. The ligaments are as follows: anterior superficial posterior sacro-coccygeal, which are continuations of


Fig. 573.— View of Pelvic Skeletal Structures from Above and in Front.

anterior and posterior longitudinal ligaments of the bodies of the tebrae; intercornual, which pass between the sacral and coccygeal nua; and lateral sacro-coccygeal, which pass between the inferior iral angles of the sacrum and the transverse processes of the first cygeal vertebra. The latter ligament is liable to become ossified. Arterial Supply .—Inferior lateral and median sacral arteries.

A 1 erve-supply .—Lower two sacral and coccygeal nerves.

Movements .—Forward and backward movements are allowed. Intercoccygeal Articulations.—These only exist prior to middle

. The union between the coccygeal segments is effected by inter'tebral discs, and anterior and posterior ligaments. The adjacent res of the sacro-tuberous and sacro-spinous ligaments serve as lateral unents.


Sacro-iliac Articulation. — This belongs to the class of syno joints. The bony elements are the auricular surfaces of the sacrum ; ilium. The cartilages of the auricular surface are about x \ inch th and exist as two plates, one for each surface, a small but definite syno cavity existing between the two plates. The ligaments at the j( are anterior, and long and short posterior. The anterior sacro-i ligament is composed of short fibres which are placed in front of joint. The short posterior sacro-iliac ligament, which is very strc extends from the ligamentous surface of the ilium to the ligament surface of the sacrum and the tubercles on the dorsum of the bone,


Fig. 574. —Ligaments of the Right Half of the Pelvis

(Posterior View).


direction of the fibres being downwards and inwards. The 1 ( posterior sacro-iliac ligament lies superficial to the posterior, s extends from the posterior superior iliac spine and the adjacent p of the iliac crest to the third and fourth series of tubercles on the dors of the sacrum. It is really a detached part of the short posterior sac iliac ligament. The great and small sacro-sciatic ligaments are acc sory to this joint.

The sacro-tuberous ligament (great sacro-sciatic ligament) is attached by one extremity to the posterior inferior iliac spine, and sides of the last three sacral and first coccygeal vertebrae, and by

extremity to the inner border of the ischial tuberosity. From atter point it sends forwards an expansion, called the falciform ss, which is attached to a sharp ridge on the lower part of the inner

e of the ramus of the ischium close to its medial border. The ent is broad at its attached ends, especially the upper, but in

n g towards the ischial tuberosity it becomes narrow. Its direction inwards and forwards, aild its ischial fibres are continuous with endinous origin of the long head of the biceps femoris. By its Trial surface it gives origin to part of the gluteus maximus, and lg on this surface are the plexiform loops formed by the lateral dies of the posterior primary divisions of the first three sacral

s. Its deep surface gives origin to some fibres of the pyriformis, lower down is intimately connected with the sacro-spinous ligaThe falciform process affords attachment to the lower part of jarietal pelvic fascia. The sacro-tuberous ligament is pierced by

occygeal branch of the inferior gluteal artery, the sacral branch e internal pudendal artery, and the perforating cutaneous nerve the sacral plexus. The ligament assists in the formation of the

er and lesser sciatic foramina. ie sacro-tuberous ligament is to be regarded as a detached portion of the lead of the biceps femoris muscle.

he sacro-spinous ligament (small sacro-sciatic ligament), which is gular, is attached by its base to the sides of the last two sacral first coccygeal vertebrae, where it is intimately connected with the i superficially placed sacro-tuberous ligament. Its apex is attached Le tip of the spine of the ischium. Its deep surface is incorporated the coccygeus muscle, and along with the spine of the ischium it s the separation between the greater and lesser sciatic foramina.

he sacro-spinous ligament is to be regarded as resulting from the fibrous leration of the superficial part of the coccygeus muscle.

I rterial Supply of the S acro-iliac Articulation. —Ilio-lumbar, superior al sacral, and superior gluteal arteries.

lerve-supply .—Superior gluteal and anterior primary divisions, lateral branches of the posterior primary divisions of the first- two il nerves.

Movements .—Stability being required at this joint, it is almost ovable. The two hip bones by their union at the pubic articulation 1 an arch, the convexity of which is directed downwards and forts. The piers of this arch are separated by a wide interval into

h the sacrum fits. The sacrum being narrower behind than in t, the superincumbent weight of the trunk has a tendency to dise it downwards into the pelvic cavity, but this is resisted partly the powerful posterior sacro-iliac ligaments, which suspend the 3 , and partly by the strong hold which the sacrum has upon the a, in virtue of the irregularities of the opposed surfaces. Under influence of the superincumbent weight there is a tendency on the part of the sacrum to rotate round an axis passing transversely thro the sacro-iliac joints. This tendency, however, is checked by sacro-spinous and sacro-tuberous ligaments. The ilio-lumbar 1 Superior Pubic Ligament ments prevent displacement of fifth lumbar vertebra over base of the sacrum.


Fig. 575. — The Ligaments of the Symphysis Pubis (Anterior Aspect)



The Pubic Symphysis.—1 belongs to the class of seconc cartilaginous joints. The artici surfaces are the symphysial pects of the pubic bones, ligaments are anterior, postei superior, inferior, and interpi disc. The anterior pubic ligair is strong, and is composed superficial and deep fibres, superficial fibres are arranged an obliquely decussating man] and are chiefly constructed by aponeurotic fibres of the extei oblique and inner heads of recti abdominis muscles. The deep fibres are disposed transvers The posterior and superior pubic ligaments are weak, and consis scattered fibres. The inferior ligament (arcuate ligament) is a strc thick band of fibres, which lies at the antero-superior part of pubic arch, where it fills up and rounds off the subpubic angle. I attached superiorly to the lower part of the interpubic disc, and laterally to the adjacent parts of the inner lips of the inferior pubic rami. It is about | inch in depth, and is slightly arched, from which latter circumstance it is known as the arcuate ligament. The interpubic disc lies between the plates of cartilage which cover the bony articular surfaces. It is composed of fibro-cartilage, is thicker in front than behind, and usually contains a fissure at its upper and back part, which may extend for one-half, or even the whole length, of the disc as an oblique cleft parallel to the plane of the bony surfaces. This fissure is brought about by absorption of the tissues in that situation, and it does appear until about the tenth year of life. It is larger in the fer than in the male.


Fig. 576. — Vertical Section the Pubic Symphysis.



Ihe depth of the symphysis pubis is less in the female than in male.




Arterial Supply .— Pubic branches of the inferior epigastric and rator, and superficial external pudendal arteries.

Nerve-supply . — Probably the hypogastric branch of the ilio-hypo•ic, ilio-inguinal, and pudendal nerves.

Movements . — Very slight separation is allowed at this joint, due to ing of the connecting structures. This is most apparent during nancy and parturition.

Greater Sciatic Foramen. — This foramen is formed by the greater ic notch, the spine of the ischium, the sacro-tuberous ligament, the sacro-spinous ligament. For its compartments and the struc3 which pass through them, see p. 534.

Lesser Sciatic Foramen. — This foramen is formed by the lesser

ic notch, the spine of the ischium, the sacro-tuberous ligament, and sacro-spinous ligament. For the structures which pass through it, iluteal Region.

Obturator Membrane and Obturator Canal.

die obturator membrane is attached to the posterior margin of the imference of the obturator foramen, except superiorly opposite the Lrator groove; this last it converts into a hbro-osseous canal for passage of the obturator vessels and nerve. In this situation it is sd posteriorly by the parietal pelvic fascia. Its fibres are arranged n irregular, decussating manner. Its posterior or pelvic surface is dy covered by the obturator internus muscle. The anterior or oral surface is in like manner covered by the obturator externus cle, and at its circumference there is an arterial loop formed by the

erior and anterior terminal branches of the obturator artery, rhe obturator canal is a hbro-osseous canal, which is situated above upper border of the obturator membrane. Its upper boundary,

h represents the osseous element, is formed by the obturator groove he inferior surface of the superior pubic ramus, the direction of the we being downwards, forwards, and inwards. The lower boundaiy, ch represents the fibrous element, is formed by the junction of the ietal pelvic fascia with the upper border of the obturator membrane r the upper border of the obturator internus. d he canal transmits obturator vessels and obturator nerve, the nerve being above the jry.