Difference between revisions of "Book - Buchanan's Manual of Anatomy including Embryology 11"

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=Chapter XI The Abdomen=
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==Male Perineum==
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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.
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The perineum practically corresponds with the outlet of the pelvi* and is somewhat lozenge-shaped, having the subpubic angle in from
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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.
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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
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Fig. 404.—Lower Aperture of Male Pelvis.
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SP, subpubic ligament; ST, sacro-tuberous ligament; T, tuber ischii.
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muscles (Hilton). The position of each ischio-rectal fossa is indicated y a slight depression between the anus and ischial tuberosity.
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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.
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Ischio-rectal Division.
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Cutaneous Nerves. —These are (1) the perineal branch from the iwer part of the anterior primary division of the fourth sacral, and
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) the inferior hsemorrhoidal nerve, a branch of the pudendal. The
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>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.
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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.
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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.
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Muscles. —The muscles in this division are the corrugator cutis ani, dhncter ani externus, levator ani, and coccygeus.
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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.
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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.
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For the levator ani and coccygeus, see pp. 947 and 948.
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Sphincter Ani Externus — Origin. —The tip of the coccyx and the bn over it.
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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.
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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.
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Action .—To keep the anal aperture closed, at the same time proving a wrinkled condition of the skin.
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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.
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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
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Fig. 405. —Dissection of the Male Perineum. On the left side the bulbo-spongiosus has been removed and the crus penis cut.
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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.
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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
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anal. The perineal vessels and nerves, branches respectively of the
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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
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utaneous branch from the sacral plexus, are to be seen.
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The fossa is filled with loose fat, which also extends into the anterior ind posterior diverticula.
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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
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he anal canal about inch above the anus. If the discharge is effected in either
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)r both of these two ways a fistulo in ano is the result.
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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.
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Uro-genital Division.
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Superficial Fascia. — The superficial fascia resembles that over the ower part of the anterior wall of the abdomen in being divisible into
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wo layers, which are called the superficial layer and the deep layer.
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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.
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The deep layer (Fascia of Colles) is membranous and strong.
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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.
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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.
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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.
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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.
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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.
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Muscles—Transversus Perinaei Superficial^ (Fig. 406)— Origin.The ramus of the ischium superficial or deep to the ischio-cavernosus.
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Insertion .—The perineal body.
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Nerve-supply .—The deep division of the perineal branch of th pudendal nerve.
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Action .—To draw back and fix the perineal body, and so to aid he action of the bulbo-spongiosus.
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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.
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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.
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Fig. 406. —Superficial Dissection to show Perineal Muscles and
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ISCHIO-RECTAL FOSSA.
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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.
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Nerve-supply .—The deep division of the perineal branch of the pudendal nerve.
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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.
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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.
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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.
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Insertion .—The muscle, as regards its insertion, is convenientl divided into three parts—namely, the chief part, the anterior par and the posterior part.
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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.
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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.
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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.
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Nerve-supply .—The deep division of the perineal branch of th pudendal nerve.
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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.
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The chief portions of the bulbo-spongiosus muscles complete! surround the bulb, and may be regarded as forming a sphincter muscle
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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.
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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
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regarded as a separate muscle—the deep transverse muscle of the perineum.
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Nerve-supply .— The dorsal nerve of the penis.
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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
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o the maintenance of erection of the penis by compressing the veins
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rom the corpora cavernosa and bulb. (3) To compress the bulborrethral glands, and so aid in the expulsion of their secretion.
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Fig. 407. — Deep Dissection of the Male Perineum. The rectum has been turned back.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Fig. 408. — The Perineal Membrane. The antero-inferior layer has been removed on the left side.
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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.
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Openings for the Arteries of the Bulb. —These are situated one on
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either side of the urethral opening.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Structures between the Layers of the Perineal Membrane.— These are as follows:
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# The membranous portion of the urethra in great part.
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# The bulbo-urethral glands..
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# The sphincter urethrae muscle.
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# 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.
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# 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.
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# The deep lymphatics of the penis and urethra.
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# The dorsal nerves of the penis, each of which lies lateral to the corresponding internal pudendal artery.
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===Bulbo-urethral Glands (Cowper’s)===
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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.
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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.
 +
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 +
The bulbourethral glands are developed from the epithelial lining of the urc genital sinus.
 +
 +
 +
 +
Fig. 409.— Plan of Left Internal Iliac Artery.
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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.
 +
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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.
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 +
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.
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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.
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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.
 +
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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.
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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.
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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.
 +
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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.
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 +
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<
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Scrotum
 +
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Deep Layer of Superficial Perineal Fascia (right half)
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Superficial Perinealf Nerves f
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Long Perineal Nerve
 +
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Superficial Transverse Perineal Muscle
 +
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Inferior Hasmorrhoidal Nerve
 +
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Gluteal Cutaneous Branches of Posterior Cutaneous Nerve of Thigh
 +
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Perforating Cutaneous Nerve
 +
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-Perineal Body
 +
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-Superficial Perineal Artery
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-Transverse Perineal Artery
 +
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__ Internal Pudendal Artery ii the Pudendal Canal V— Inferior Rectal Artery
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- Gluteal Cutaneous Branche: of Inferior Gluteal Artery
 +
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Perineal Branch of 4th Sacral Nerve
 +
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Fig. 410.—Dissection of the Male Perineum.
 +
 +
On the left side the bulbo-spongiosus has been removed and the crus
 +
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penis cut.
 +
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 +
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.
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 +
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.
 +
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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.
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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.
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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.
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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.
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The dorsal nerve of the penis is at first contained in the pudendal
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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.
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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.
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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.
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==Female Perineum==
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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.
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===Uro-genital Division===
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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.
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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.
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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
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THE ABDOMEN
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693
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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
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Mons Pubis—«=.
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M\u
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Anterior Commissure
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jf
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Labium Majus
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- Labium Minus ' External Urethral Orifice
 +
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-External Orifice of Vagina
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Vestibular Fossa Frenulum Labiorum Posterior Commissure
 +
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Fig. 411.—The External Genital Organs of the Female.
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lood-supply and nerve-supply of the labia majora correspond with hose of the scrotum.
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 +
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.
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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
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694
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A MANUAL OF ANATOMY
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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.
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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.
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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
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THE ABDOMEN
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695
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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.
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 +
Lymphatics. —The lymphatics of the prepuce of the clitoris accompany those if the labia majora, and pass to the superficial inguinal glands.
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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. . .
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 +
The lymphatics of the corpora cavernosa pass to the internal iliac glands on
 +
 +
iither side.
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 +
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.
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The vestibule represents the remains of the uro-genital sinus.
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 +
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.
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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
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6g6
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A MANUAL OF ANATOMY
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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.
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 +
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.
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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.
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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.
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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
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THE ABDOMEN
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697
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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.
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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.
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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
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Fig. 413.—The External Genital Organs at the End of the Indifferent Stage seen from the Front and from the Side.
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GF, labio-scrotal fold; GS, genital swelling; GT, genital tubercle.
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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.
 +
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These glands are homologous with the bulbo-urethral glands, and their structure is similar.
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The greater vestibular glands are developed from the lining epithelium of the uro-genital sinus.
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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.
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Development of the External Genital Organs.
 +
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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.
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6 g8
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A MANUAL OF ANATOMY
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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.
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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
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Male. Female.
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RapM of Penis^ Gians Penis Gians Clitoridis Genital Swelling
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Fig. 414.—Development of the External Genital Organs.
 +
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is seen to extend forward on the lower aspect of the growing genita tubercle.
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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.
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The genital eminence undergoes lengthening, and gives rise to the plitons, The terminal extremity of the eminence becomes enlarged,
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THE ABDOMEN 699
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md forms the glans clitoridis, whilst the remainder gives rise to the zorpora cavernosa clitoridis.
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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.
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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.
 +
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Fig. 415.— Figures of Male and Female Organs at the End of
 +
 +
the Second Month.
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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.
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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.
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The bulbs of the vestibule and the pars intermedia are developed as masses of erectile tissue close to the labia minora and clitoris.
 +
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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
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700
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A MANUAL OF ANATOMY
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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.
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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.
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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
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Fig. 416. —Male External Organs during the Third and Early
 +
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Part of Fourth Month.
 +
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the canal formed in this way becomes continuous with the spongy urethra.
 +
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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.
 +
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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.
 +
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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.
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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.
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THE ABDOMEN
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701
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It is to be noted that, whilst the prostatic and membranous portions
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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.
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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.
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Perineum Proper.
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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.
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Perineal Body. —It is situated between the anus and the vaginal [fice. It is triangular in outline, and is about ib inches in breadth.
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Fig. 417. —Female Bony Pelvis from Below.
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ST =sacro-tuberous ligament; IP =ischio-pubic ramus.
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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
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ternal sphincter, levatores ani, and bulbo-spongiosus muscles. It
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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.
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Perineal Membrane. —The perineal membrane resembles that of te male in being composed of two layers, inferior and superior.
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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
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702
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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Anal Division.
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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.
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Muscles. —The muscles of the female perineum, as compared wil those of the male, present certain differences.
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Levatores Ani. —The anterior fibres of these muscles embrace tl vagina instead of the prostate gland, as in the male.
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Ischio-cavernosus (Erector Clitoridis). —This muscle replaces tl ischio-cavernosus of the penis, and is of small size.
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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.
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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
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THE ABDOMEN
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7°3
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is almost completely divided into two parts by the vagina. The
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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.
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The external sphincter and superficial transverse perineal muscles re similar to those in the male.
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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.
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The superficial perineal artery is larger than in the male, and is istributed to the labium majus.
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The artery of the bulb is of comparatively small size, and is disributed to the bulb of the vestibule.
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Ischio-cav., on Crus. Cavernosus
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Bulbo. Sp. on Bulb Perineal Membrane Sup. Trans. Perinei
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Fig. 418. —Ischio-rectal Fossa and Muscles of Female Perineum.
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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.
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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.
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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
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7 o 4
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A MANUAL OF ANATOMY
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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.
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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.
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The pudendal nerve and its branches are similar to those in the male, the superficial perineal nerves being distributed to the labia majora.
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ABDOMINAL WALL.
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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.
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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.
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THE ABDOMEN
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7°5
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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
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he xiphoid process of the sternum. The relation of the stomach to it
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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
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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
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he umbilicus. The coils of the jejunum and ileum, also covered by the
 +
greater omentum, lie behind it below the umbilicus.
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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.
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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.
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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.
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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
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45
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706
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A MANUAL OF ANATOMY
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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.
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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 ;
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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
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THE ABDOMEN
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707
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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.
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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.
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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.
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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.
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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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708
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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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.
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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.
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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.
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The right iliac fossa contains the terminal part of the ileum, the caecum, the vermiform appendix, and beginning of the ascending colon.
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I he left iliac fossa contains the iliac part of the descending colon.
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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
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appendix is a point on an average rather more than 1 inch below the ileo-colic valve.
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THE ABDOMEN
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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.
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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.
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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.
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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.
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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
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A MANUAL OF ANATOMY
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710
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anterior abdominal wall, does not pass downwards to the front of th thigh, but takes an upward course.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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THE ABDOMEN
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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,
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Fig. 420. —Cutaneous Nerves of the Trunk (Antero-lateral
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View) (after Henle).
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1-12, anterior cutaneous; 2-12, lateral cutaneous.
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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.
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The venae comites of this artery terminate in one vessel, which joins the long ■saphenous vein.
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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
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712
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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The vein corresponding to this artery terminates in the long saphenous veil
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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.
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The veins corresponding to these arteries terminate in the inferior and superb epigastric veins.
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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
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The veins corresponding to these arteries are tributaries of the lower frv posterior intercostal and subcostal veins.
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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.
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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]
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THE ABDOMEN
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7 i 3
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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
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Superficial Dorsal Vein (Deep) Dorsal Vein Dorsal Artery Dorsal Nerve
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Corpus Cavernosum Penis Artery of Corp. Cav. Penis Fascial Sheath
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Corpus Spongiosum Urethra
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Artery of Corp. Spong.
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Fig. 421.—Diagram of Section across the Penis (Enlarged).
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/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.
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this way the dorsal vein is compressed during the action of these,
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t the root of the organ the fascial investment blends with the two Vers of the suspensory ligament.
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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
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A MANUAL OF ANATOMY
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7 M
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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.
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The Dorsal Arteries. —For the description of these arteries, s
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p. 688.
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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.
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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
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which terminate in the right ar left portions of the prostat plexus of veins.
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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
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For a description of tl dorsal nerves of the penis, sf p. 689.
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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 (
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Fig. 422.—Plans to show Structure of Penis.
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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.
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THE ABDOMEN
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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.
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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.
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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
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e P inguinal glands or through the femoral and inguinal canals to the
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ands forming the medial and lateral chains respectively of the external ac glands.
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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
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716
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A MANUAL OF ANATOMY
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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.
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Fig. 423.—Plan of Structure of Scrotal Walls.
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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.
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The tunica vaginalis testis is the park
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layer of the tunica vaginalis.
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The subperitoneal areolar tissue is compo of areolar and adipose tissues, and a cert amount of plain muscular tissue.
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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.
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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.
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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.
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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.
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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
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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.
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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
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THE ABDOMEN
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717
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he scrotal chamber and superiorly to the under surface of the root he penis.
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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.
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The veins corresponding to these arteries terminate in the long henous and internal pudendal veins.
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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.
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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.
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Nerve-supply. —The nerves of the scrotum are as follows: (1) the
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ral and medial posterior scrotal branches of the pudendal; (2) the
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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.
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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
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he inguinal ligament.
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Nerve-supply .—The lower five intercostal nerves and the subcostal
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ve.
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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.
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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
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718
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A MANUAL OF ANATOMY
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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
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Pectoralis Major
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Serratus Anterior _
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Latissimus Dorsi
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Obliquus Externus Abdominis
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Lumbar Triangle
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Middle Tendinous , l|u i Intersection
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^.-Umbilicus
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_Rectus Abdominis
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_.Anterior Superior
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Iliac Spine
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.Inguinal Ligament
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Spermatic Cord at 4 jri- Superficial Inguinal Ring
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Fig. 424.—The External Oblique Muscle.
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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.
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THE ABDOMEN
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710
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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.
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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.
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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
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ia iliaca, which are attached to its lateral portion, forming a canal containing
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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
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ral cutaneous nerve of thigh.
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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.
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The pectineal part of inguinal ligament (Gimbernat’s) is the reflection
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he inguinal ligament from the pubic tubercle along the pectineal line,
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length is fully 1 inch, and it is triangular, the apex being at the
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>ic tubercle. It presents three borders and two surfaces. Two of
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! borders are fixed, one, called the inguinal border, being continuous
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h the inner end of the inguinal ligament, and the other, called the
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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
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ligamentum teres of the uterus in the female. The fascia transrsalis is attached to the base of the ligament on its abdominal
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}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,
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720
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A MANUAL OF ANATOMY
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and the pectineus muscle and pubic lamina of the fascia lata are front of its pectineal attachment.
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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
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Fig. 425. —Anterior View of Muscles and Aponeuroses.
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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.
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crest. A portion of the fascia is seen lying in the lower and inner par of the superficial inguinal ring.
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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
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THE ABDOMEN
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721
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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
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the opposite side, the fibres from the right side being superficially
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laced. An interval is thus left between these diverging bundles, hich is widest at the lower and inner part, where it corresponds with
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Pectoralis Major
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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
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46
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722
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A MANUAL OF ANATOMY
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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.
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The linea alba has been already described (see p. 704).
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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.
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Obliquus Internus Abdominis — Origin. —(1) The deep or abdominal surface of the inguinal ligament over its outer half or two-thirds;
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(2) the middle lip of the iliac crest over its anterior two-thirds; and
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(3) the posterior layer of the lumbar fascia of the transversus abdominis.
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Insertion. —(1) The lower borders of the cartilages of the lower
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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.
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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.
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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.
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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
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THE ABDOMEN
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723
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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.
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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.
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Qie fibres descend in a series )f loops upon the outer and interior aspects of the spermatic cord. The lowest loops reach the
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unica vaginalis of the testis, upon the upper part of which they
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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
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Fig. 426A. —Diagram to show how the Lower Fibres of Internal Oblique form a Cremaster Muscle (CM)
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CONTINUOUS WITH CREMASTERIC FASCIA (CF).
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I.Sp.F., internal spermatic fascia;
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C, conjoint tendon.
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724
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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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.
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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
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THE ABDOMEN
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725
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xr is connected with the spinous processes of the lumbar and sacral
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tebne and the posterior fourth of the outer lip of the iliac crest, by
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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.
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Insertion. —(1) The linea alba; (2) the pubic crest; and (3) the Mial portion of the pectineal line for 1 inch.
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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.
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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.
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For the posterior aponeurosis of the muscle, see p. 840.
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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.
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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.
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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.
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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
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726
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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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.
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Nerve-supply .—The lower five intercostal nerves and the subcosf nerve.
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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.
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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.
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THE ABDOMEN
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727
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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.
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Pyramidalis — Origin .—The front of the pubic crest.
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Insertion .—The linea alba for 2 inches or more above the symphysis pubis.
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Nerve-supply .—The subcostal nerve.
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Action .—To render tense the linea alba.
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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.
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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.
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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
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728
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A MANUAL OF ANATOMY
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versalis, and so enter the sheath of the rectus. These vessels, as th course upwards, pass anterior to the fold.
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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.
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Relation of Structures at the Pubic Crest. —The relation of structures fn
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before backwards is as follows:
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1. The reflected part of inguinal ligament.
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2. The conjoint tendon splitting medianly to enclose the lateral margins the pyramidalis and rectus.
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3. The pyramidalis.
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4. The outer head of the rectus abdominis.
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5. The fascia transversalis.
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A few fibres of the cremaster are inserted into the pubic crest close to the pul tubercle.
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Relation of Structures at the Medial Portion of the Pectineal Line. —The relati<
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of structures from before backwards is as follows:
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1. The pubic lamina of the fascia lata, incorporated with which is the pectinc (ligament of Cooper) ligament.
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2. The pectineus.
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3. Pectineal part of inguinal ligament.
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4. The conjoint tendon.
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5. The fascia transversalis and the deep femoral arch.
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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.
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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.
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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
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THE ABDOMEN
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7 2 9
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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
 +
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is in series with the nterior cutaneous nerves.
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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.
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[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,
 +
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/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.
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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
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Fig. 428. —Deep Nerves of Abdominal Wall
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LYING BETWEEN TRANSVERSUS AND INTERNAL
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Oblique (IO).
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730
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A MANUAL OF ANATOMY
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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
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P 1
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Fig. 429.— Scheme of Vascular Anastomosis on the Posterior Wall
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Sheath of Rectus.
 +
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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
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THE ABDOMEN
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73 i
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ne corresponding with the centre of the rectus, and distant from the nea alba about i| inches.
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Branches. —These are as follows: cremasteric, pubic, muscular, iitaneous, peritoneal, and terminal or anastomotic.
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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
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replaced in the female by the artery of the ligamentum teres of the
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ter us.
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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.
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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.
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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.
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The peritoneal branches pierce the posterior wall of the sheath of he rectus, to be distributed to the adjacent parietal peritoneum.
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The terminal or anastomotic branches enter the rectus above the svel of the umbilicus, and anastomose with the superior epigastric of the nternal mammary.
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For the abnormal obturator artery, see p. 566.
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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.
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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
 +
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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.
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732
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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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.
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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.
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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.
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The veins corresponding to the lower two posterior intercost: arteries terminate in the corresponding intercostal veins. The subcost;
 +
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THE ABDOMEN
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733
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ein of the right side terminates in the azygos vein, and that of the
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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.
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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.
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The deep lymphatics of the lower part of the lateral abdominal r all accompany the abdominal branches of the lumbar arteries, and
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Intercrural Saphenous Superficial X Interfoveolar
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Fibres Opening Inguinal Ring Ligament
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ig. 430. —Superficial and Deep Dissection of the Lower Part of the Anterior Abdominal Wall (after Cooper).
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E. O.A. External Oblique Aponeurosis I.A.R. Deep Inguinal Ring
 +
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O.I.A. Obliquus Internus Abdominis S.C. Spermatic Cord
 +
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T.A. Transversus Abdominis D.E.V. Inferior Epigastric Vessels
 +
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F. T. Fascia Trans versalis X. Reflected Part of Inguinal Ligament
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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.
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For the superficial lymphatics of the antero-lateral abdominal fall, see p. 712.
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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
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734
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A MANUAL OF ANATOMY
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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
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Gbliquus Internus Abdominis
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Transversus Abdominis-/ r
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Gbliquus Externus,. Abdominis
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Pectineus_—- 0
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Sartorius _ Adductor Longus
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Umbilicus
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I
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_Rectus Abdominis
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— Spermatic Cord
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. Suspensory Ligament of Penis
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Ilio-inguinal Nerve
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Fig. 431.— Dissection of the Inguinal Region.
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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
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THE ABDOMEN
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735
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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.
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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
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M. Oblig. Interims Transversalis Fascia Conjoint Tendon
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Aponeurosis of Oblig. Ext.
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Ext. Spermatic Fascia Cremasteric Fascia Int. Spermatic Fascia Spermatic Cord.
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ig. 432. —Scheme to show the Composition of the Front and Back Walls of Inguinal Canal, and Derivations of Coverings of the Cord.
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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.
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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
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meeting between the fascia transversalis and the inguinal ligament, ms portion of it presents a groove, which lodges the spermatic cord.
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1 the lower third the floor is formed by the abdominal surface of the
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736
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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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.
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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.
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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
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THE ABDOMEN
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737
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thirds of the canal it is accompanied by the ilio-inguinal nerve,
 +
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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
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r iG. 433 - —Transverse Section of the Vas Deferens, showing its
 +
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Minute Structure.
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! 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
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47
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738
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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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.
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The vein from the vas opens into the vesical plexus of veins, a thence into the internal iliac vein.
 +
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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.
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For the cremasteric artery, see p. 731.
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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.
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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.
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THE ABDOMEN
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739
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Coverings of the Spermatic Cord. —The coverings, enumerated from Tin outwards, are as follows:
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 +
1. The subperitoneal areolar tissue, which is continuous with that the abdominal wall through the deep inguinal ring.
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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.
 +
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Testicular Artery
 +
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Pampiniform Plexus of Vein.
 +
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Epididymal Branch of Testicular Artery
 +
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Glandular Branch of Testicular Artery
 +
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Appendices Testis
 +
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Artery of the Vas Deferens Vas Deferens
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Pampiniform Plexus of Veins
 +
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— Sinus of Epididymis
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Fig. 434. —Dissection of the Spermatic Cord, showing the Bloodvessels and Duct of the Testis (after Sappey).
 +
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4. The external spermatic fascia.
 +
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5- The dartos muscle.
 +
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6. The skin.
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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
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tus.
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The fibres of the cremaster proper are of the striated variety, but ose of the internal cremaster are of the plain variety.
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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.
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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.
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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.
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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.
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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
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Fig. 435. —Diagram showing the Descent of the Testis. A, first stage; B, second stage; C, final stage.
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1 . Testis (in Abdomen) 4. Subperitoneal Areolar Tissue
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2. Primitive Peritoneum (Tunica Adnata) 5. Fascia Transversalis
 +
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3 ; Parietal Peritoneum 6. Deep Inguinal Ring
 +
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3. Processus Vaginalis 7. Integument
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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
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THE ABDOMEN
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74i
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ese fibro-muscular elements, there are superadded striated muscular fibres rived from the internal oblique and transversus abdominis muscles in the form
 +
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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,
 +
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raparietal, and scrotal—and throughout all these stages it follows the lead
 +
the gubernaculum, which necessarily undergoes shortening.
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 +
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.
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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.
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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
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B C
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Parietal A —-^— -- N ^
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Fig. 436. —Varieties of the Tunica Vaginalis.
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A, normal type; B, congenital type; C, infantile type.
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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.
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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 :
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1. Extraperitoneal areolar tissue.
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2. Fascia transversalis.
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3. Lowermost inguinal fibres of internal oblique muscle (cremaster).
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4. External oblique aponeurosis.
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5- Both layers - of anterior abdominal wall fascia (dartos muscle).
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6. Skin of scrotum.
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742
 +
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 +
A MANUAL OF ANATOMY
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 +
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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.
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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.
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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
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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.
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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.
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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
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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).
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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]
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THE ABDOMEN
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743
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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.
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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
 +
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uinal ring, and sometimes as low as the tunica vaginalis.
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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.
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Abnormal Conditions of the Vaginal Process—Congenital Type. —(1) The
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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.
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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.
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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.
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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.
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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.
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Umbilicus
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Intermediate Inguinal Recess
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Medial Inguinal Recess
 +
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Fig. 437 -—The Folds and Recesses on the Posterior Surface of
 +
 +
the Anterior Abdominal Wall.
 +
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 +
Peritoneal Folds and Inguinal Recesses.—The peritoneum lining i posterior surface of the anterior abdominal wall below the umbili< presents folds and recesses.
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 +
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
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THE ABDOMEN
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7 45
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duced by the inferior epigastric artery, and is called the fold of the inferior epigastric artery.
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 +
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.
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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.
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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
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The coverings, enumerated in order from within outwards, are as follows:
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1. Parietal peritoneum, which forms the sac.
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2. Extraperitoneal tissue.
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3 - Fascia transversalis, from the margins of the deep inguinal ring, forming
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 +
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.
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746
 +
 +
 +
A MANUAL OF ANATOMY
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 +
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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.
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 +
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.
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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:
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1. Parietal peritoneum.
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2. Extraperitoneal tissue.
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3. Fascia transversalis.
 +
 +
4. Conjoint tendon.
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5. Fascia triangularis.
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 +
6. External spermatic fascia.
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7. Dartos muscle.
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8. Skin.
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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.
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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:
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 +
1. Parietal peritoneum. 5. External spermatic fascia.
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 +
2. Extraperitoneal tissue. 6. Dartos muscle.
 +
 +
3. Fascia transversalis. 7. Skin.
 +
 +
4. Cremasteric fascia.
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 +
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 +
THE ABDOMEN
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747
 +
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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
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 +
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
 +
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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
 +
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A MANUAL OF ANATOMY
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748
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is exposed in operating, two of these belonging to the invaginated funicular proc( and the other representing the wall of the hernial sac.
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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:
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1. Parietal peritoneum.
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2. Extraperitoneal tissue.
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3. Fascia transversalis.
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4. An expansion from the decussating fibres of the aponeuroses
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of the abdominal muscles of opposite sides.
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5. Superficial fascia.
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6. Skin.
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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.
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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.
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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.
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The Tunica Vaginalis and Testis.
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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,
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THE ABDOMEN
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749
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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.
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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
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Spermatic Cord
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Paradidymis
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Parietal Layer of Tunica Vaginalis
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Epididymis Sinus of Epididymis
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Fig. 438.—The Testis and its Coverings.
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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.
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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
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A MANUAL OF ANATOMY
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border, where there is a duplicature of that membrane containin bloodvessels and attaching it to the testis.
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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.
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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.
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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.
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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.
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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.
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Nerve-supply.—The testicular plexus of the sympathetic system which derives its fibres from the aortic and renal plexuses.
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The testis is homologous to the ovary of the female (testis muliebris)
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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
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THE ABDOMEN
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75i
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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
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Parietal Layer of Tunica Vaginalis
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— Visceral Layer of Tunica Vaginalis
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Tunica Albuginea Lobe of Testis
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Mediastinum Testis
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[.Sinus of Epididymis - - Epididymis
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Testicular Artery
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Vas Deferens
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! Testicular Veins
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«
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Artery of the Vas Deferens
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Fig. 439. —Diagram showing a Transverse Section of the Testis and Scrotum.
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unite into one, and the tubules of Wall 0 f Scrotum
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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.
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The epididymis consists of one tube, having a diameter of about ^ inch
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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
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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
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Vas Deferens
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Aberrant
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Ductule
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Head of Epididymis
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•"Lobules of Epididymis
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Body of Epididymis
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"Mediastinum Testis
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l—Lobe of Testis
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Tunica Albuginea
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Tail of Epididymis
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Fig. 440.—The Structure of the Testis and
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Epididymis.
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75 2
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A MANUAL OF ANATOMY
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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 ,
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(3) The primary spermatocytes a
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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
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S, Sertoli cell; P, interstitial cells. basement membrane lined with a sin£
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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.
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The structure of the epididymis is similar to that of the efferent ducts ai lobules.
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Development of the Internal Sexual Organs.
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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.
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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
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THE ABDOMEN
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753
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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.
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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.
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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.
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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
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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
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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.
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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.
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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.
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A MANUAL OF ANATOMY
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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.
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ABDOMINAL CAVITY.
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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
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hie. 442 .—Diagrams to show Extent and Disposition of Abdominal Ca\ from Reconstructions in Coronal and Sagittal Planes.
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D, diaphragm; LA, levator ani; A, abdominal cavity; P, pelvic cavity; FP, 1 pelvis; b, brim of pelvis, made by psoas major muscle.
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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
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THE ABDOMEN
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755
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>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.
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Abdomen Proper.
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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.
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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.
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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
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75 ^ A MANUAL OF ANATOMY
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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
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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.
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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.
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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
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Fig. 443.
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-Addison’s Lines on the Abdomen,
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AS DESCRIBED IN TEXT.
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beyond the xiphoid process. The great
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THE ABDOMEN
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757
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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.
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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
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mall Intestine
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Gall Bladder Stomach
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Trans. Colon
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Cosc.um
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Bladder
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I.iver
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Fig. 444.—Anterior View of the Abdominal Viscera in situ.
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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
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For the distinction between an omentum, a mesentery, and a peritoneal
 +
gament, see p. 779 et seq.
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758
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A MANUAL OF ANATOMY
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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.
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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
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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.
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IE
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Fig. 445. —The Stomach (External View).
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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).
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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
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THE ABDOMEN
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759
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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:
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1. The diaphragm.
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2. The gastric surface of the spleen.
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3. Thejeft suprarenal gland.
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4. The gastric area at the upper part of the front of the left kidney.
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5. The antero-superior surface of the pancreas.
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6. The upper surface of the transverse colon.
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7. The upper surface of the transverse meso-colon.
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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
 +
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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.
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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.
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A MANUAL OF ANATOMY
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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
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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.
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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.
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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.
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THE ABDOMEN
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761
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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.
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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.
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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.
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bor the structure and development of the stomach, see pp. 856 ind 862.
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Position, Connections, and Component Parts of the Intestinal Canal.—
 +
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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.
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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
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762
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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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
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THE ABDOMEN
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763
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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
 +
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aecum is very movable, being completely covered by peritoneum. The
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Fig. 446. —Oecum with Appendix and Terminal Piece of Ileum.
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M, meso-appendix; IC, ileo-caecal fold; ICOL, ileo-colic fold.
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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.
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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.
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The caecum is subject to much variation in its position, due, no
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764
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A MANUAL OF ANATOMY
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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.
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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:
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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.
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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.
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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.
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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.
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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.
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The position occupied by the appendix is extremely variable. The norm; positions may be tabulated as follows:
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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.)
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2. It may lie on the brim of the pelvis, along the external iliac vessels, or mai project into the pelvic cavity.
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THE ABDOMEN
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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
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4. It may lie free among the coils of small intestine.
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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).
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Based on the average positions of these structures given by Addison.
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5; R may lie free underneath the caecum in a retro-caecal fossa. (This is the una most common situation according to Treves.)
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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,
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ieved to be the result of an early fixation to the abdominal wall.
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A MANUAL OF ANATOMY
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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.
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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.
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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 <
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THE ABDOMEN
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767
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very limited extent at its right and left extremities. The transverse
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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.
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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.
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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.
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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
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A MANUAL OF ANATOMY
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768
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serous membrane, which then forms behind it a mesentery, called 1 iliac meso-colon.
 +
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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.
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For the structure and development of the intestinal canal, s pp. 869 and 864 et seq.
 +
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Position, Connections, and Component Parts of the Spleen. —T]
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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.
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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.
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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
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THE ABDOMEN
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769
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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.
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The gastric impression is large, concave, and somewhat semilunar.
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looks forwards, inwards, and downwards, and accurately adapts
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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,
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)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.
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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.
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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
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49
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C —
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Fig. 448.—Visceral Surfaces of Spleen. R, renal; G, gastric; C, colic.
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A MANUAL OF ANATOMY
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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.
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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
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8tb Costal Cart.
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Fig. 449.— Transverse Section at the Level of the Twelfth Thoraci
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Vertebra (after Symington).
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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.
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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.
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THE ABDOMEN
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771
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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.
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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.
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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.
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For the structure and development of the spleen, see p. 897.
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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.
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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
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772
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A MANUAL OF ANATOMY
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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.
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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.
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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.
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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.
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THE ABDOMEN
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773
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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.
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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.
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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.
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The inferior or visceral surface looks downwards with an inclination
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774
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A MANUAL OF ANATOMY
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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
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Inferior Vena Cava Caudate Process
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- Cys Du<
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Portal Vein
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Rena
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Impress
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Gastric Impression on Left Lobe
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/
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/ /
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Tuber Omentale ! i Hepatic Artery' / Common Hepatic Duct
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• 1 Gall-bladder
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! Quadrate Lobe
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Caudate Lobe
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Fissure for Ligamentum Venosum CEsophageal Impressior
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Suprarenal Impression i Bare Area of Right Lobe
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Duodenal Impre
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Colic Impression
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Ligamentum Teres Bile Duct
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Fig. 451. —The Inferior Surface of the Liver.
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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.
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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
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itact with the pyloric end of the stomach and first part of the )denum.
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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
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kwards: (1) the common hepatic duct; (2) the hepatic artery, accomaied by the hepatic sympathetic plexus of nerves and lymphatic
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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.
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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.
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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.
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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.
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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
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Fig. 452. —Posterior Aspect of Liver, showing Bare Area.
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FL, falciform ligament; RLL, LLL, right and left triangular ligaments.
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its lower margin; the fossa for the inferior vena cava; and the b; area of the right lobe.
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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.
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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
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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.
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Caudate lobe ( Spieghel’s lobe), with the exception of its lower margin,
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s vertically on the posterior surface. It is bounded on the right side
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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.
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The fossa for vena cava lodges a part of the inferior vena cava. It
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s vertically, and somewhat deeply, on the posterior surface, having
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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.
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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.
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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.
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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.
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For the ligaments of the liver, see p. 788.
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Excretory Apparatus of the Liver. —This consists of the hep
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ducts, the gall-bladder, the cystic duct, and the bile-duct.
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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.
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The gall-bladder is a reservoir for the bile. It is pyriform, an situated obliquely on the inferior surface of the right lobe, when
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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
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~ „ ,. ., ^ „ of the transverse colon, and behi
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dt h mm™, w : 7 s ‘f on the first P art of the duodem
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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'
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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.
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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
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)mmon hepatic ducts run parallel and in close contact with each
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her.
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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
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about 3! to 4 inches. The bile-duct sometimes opens into the lodenum independently of the pancreatic duct, but close to it.
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It is in the ampulla that a gall-stone frequently becomes lodged and fiayed in its downward progress towards the duodenum.
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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.
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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.
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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.
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For the structure and development of the liver, see pp. 884 and 888.
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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,
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■ 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
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sudden transition into the columnar ciliated epithelium of the uterine ibe.
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The peritoneum forms certain reflections or folds which are of iree kinds—namely, omenta, mesenteries, and ligaments.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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Fig. 454.— Diagram of the Peritoneum in the Adult Male (Vertical Section).
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S. Stomach S.I. Small Intestine
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P. Pancreas B. Urinary Bladder
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D. Duodenum R. Rectum
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T.C. Transverse Colon
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The arrow is through the Opening into Lesser Sac.
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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
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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.
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Transverse Course. —The peritoneum may be traced in the tn verse direction at two levels—namely, (1) above the transverse co]
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or at the level of the op
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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.
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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
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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
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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
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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
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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
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Fm. 456 .— Lines of Reflection of Peritoneum from the Posterior Abdominal Wall (from a Reconstruction).
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The arrow passes through the opening into lesser sac.
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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
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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.
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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
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Fig. 457. — Diagram of the Peritoneum at the Level of the Opening 11
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Lesser Sac (Transverse Section).
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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.
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The relations of the peritoneum to the duodenum, pancreas, a kidneys will be described when these viscera fall to be considered.
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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
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Fig. 458. — Diagram of the Peritoneum at the Level of the Umbilicus (Transverse Section).
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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.
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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
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ee , there lie between them the following structures: (1) the bile-duct
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50
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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.
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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
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(1) the superior mesenteric vessels, and the jejunal and ileal arterie
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(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.
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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.
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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.
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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
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angulated. In .very rare cases the meso-appendix is disposed in
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ch a manner as to divide the ileo-colic fossa into an upper and a lower mpartment.
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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.
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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.
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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.
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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.
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The falciform ligament is also known as the suspensory ligam
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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.
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The coronary ligament is also known as the posterior ligam
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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.
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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.
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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.
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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
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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.
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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
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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
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ns and the epigastric veins explains the enlargement of the veins of the anterior iominal wall in cases of portal obstruction within the liver.
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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.
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The ligaments of the spleen are two in number—namely, phrenicolenic or lieno-phrenic, and lieno-renal.
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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
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ament, and the left with the anterior layer of that ligament.
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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.
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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.
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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.
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The greater sac of peritoneum is the space which is exposed to view
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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).
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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
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Fig. 459.— Duodenal Recesses: Duodenum turned toward the Right.
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Arrows: 1 and 2, inferior and superior duodenal recesses, overhung by corresponding folds; 3, para-duodenal recess.
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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).
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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).
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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.
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The retro-duodenal fossa is situated behind the terminal part of the duo:num.
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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.
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Peri-caecal Recesses. —These recesses are three in number—namely, super ileo-caecal, inferior ileo-caecal, and retro-caecal.
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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.
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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
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Asc. Colon Ileum Pelvic Colon
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biG. 460.— Intersigmoid Fossa in a Child (after Poirier).
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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.
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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.
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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
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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
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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
 +
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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
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 +
 +
 +
 +
Fig. 461.— Ileo-clecal Fold and Recesses (after Jonnesco).
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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
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tentum.
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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.
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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
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 +
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Fig. 462. —The Retro-c,ecal Recess (after Jonnesco).
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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.
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The ascending and descending meso-colon, as a rule, disappear as a result of Ihesion.
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 +
The pelvic meso-colon persists and the meso-rectum disappears.
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Structure of the Peritoneum. —The peritoneum is a typical serous membrane
 +
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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.
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 +
 +
 +
s. 463.— Scheme, based on Embryonic Conditions, to show Fcetal Arrangements of Peritoneum and Composition of Transverse Mesocolon.
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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.
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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.
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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*
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 +
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Fig. 464. — The Superior Mesenteric Artery and its Branches (after Spalteholz).
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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.
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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
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)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.
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 +
The branches from the terminal arcades divide some distance away
 +
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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.
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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.
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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.
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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.
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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
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 +
Fig. 465. —Schematic Drawing to show Upper Branches of Superic
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 +
Mesenteric Artery.
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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.
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 +
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.
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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
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n. The vessel and its tributaries are destitute of valves, so that the od can regurgitate in cases of portal obstruction.
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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.
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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
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 +
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Fig. 466. —Portion of Jejunum with its Mesentery, showing Lacteal Vessels and Mesenteric Glands.
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senteric glands, terminate in from one to four lymphatic trunks, ich open into the cisterna chyli.
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 +
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.
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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
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Fig. 467. —The Inferior Mesenteric Artery and its Branches (after Spalteholz).
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lymphatics from the pre-aortic and retro-aortic glands, form 1 cisterna chyli.
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 +
Lymphatic Vessels of Ascending and Transverse Colon. —The ly
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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<
 +
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 +
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.
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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.
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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
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 +
scending colon, which in
 +
eir course form secondary Ld tertiary arcades.
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 +
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
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 +
 +
 +
Fig. 467A. — Schematic Drawing to show the Lymphatic Arrangements for Ascending and Greater Part of Transverse Colon.
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The glands are grouped along branches of the superior mesenteric artery.
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 +
 +
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
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 +
continuation of the inferior mesenteric, and will be found describ( on p. 961.
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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<
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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.
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 +
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.
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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
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 +
 +
Fig. 467B. — Scheme to illustrate the Lymphatic Drainage of Descending Colon and Iliac Loop, and Terminal Portion of Transverse Colon.
 +
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 +
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.
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 +
Their efferent vessels pass to the inferior mesenteric group of pre aortic glands.
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 +
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.
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 +
 +
 +
THE ABDOMEN
 +
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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
 +
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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
 +
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 +
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.
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 +
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.
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 +
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.
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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).
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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,
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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.
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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
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For the structure and development of the pancreas, see pp. 891, 894.
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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
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Fig. 470. —The Sympathetic System in the Abdomen and Pelvis (Hirschfeld and Leveille).
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R.K., right kidney; R.T., right testis,
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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.
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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.
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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.
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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
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ament, or through the crus of the diaphragm.) The fibres of the
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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.
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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
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Fig. 471. —Scheme of the Sympathetic Nerve in the Abdomen and Pelvis (Flower).
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S.C. Sympathetic Trunk 1,2,3,4. Lumbar Ganglia a,b,c,d, Pelvic Ganglia G.I. Ganglion Impar
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G. S. Greater Splanchnic S.S. Lesser Splanchnic L.S. Lowest Splanchnic D.P. Phrenic Plexus
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S.R.P. Suprarenal Plexus
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R. P. Renal Plexus
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S. P. Testicular Plexus A.P. Aortic Plexus
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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
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H. P. Hypogastric Plexus
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R.I.P. Jejunal and
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P.P. Pelvic Plexus E.P. Epigastric Plexus C.P. Cceliac Plexus S.P. Splenic Plexus Pa.P. Pancreatic Plexus
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L. G.P. Left Gastro-epiploic Plexus
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B. S. Branches to Spleen
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G. P. Superior Gastric Plexus
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H. P. Hepatic Plexus Pvl.P. Pyloric Plexus
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G.D.P. Gastro-duodenal Plexus
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C. P. Cystic Plexus B.L. Branches to Liver
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S.M.P. Superior Mesenteric Plexus I.C.P. Ileo-colic Plexus R.C.P. Right Colic Plexus
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M. C.P. Middle Colic Plexus Plexuses
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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The left gastric artery (coronary artery) is directed upwards and
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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.
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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.
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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.
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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
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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.
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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).
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Fig. 472. —The Arteries of the Stomach, Liver, and Spleen (after Merkel).
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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
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sser sac. It then turns forwards below the opening into lesser sac
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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
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omentum it has the bile-duct on its right side, the portal vein beii behind both.
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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
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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.
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Fig. 473.—Plan of the Relations of Portal Vein, Hepatic Artery (HA), and Bile-Ducts Behind the Duodenum (Interrupted Line), and in Lesser Omentum.
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RG, right gastric; and SD, supra-duodenal
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arteries.
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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
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ry usually passes behind the common hepatic duct, it passes in about 12 per
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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).
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The pre-pyloric vein passes from left to right, and opens into the tal vein near the pylorus.
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The right gastro-epiploic vein passes from left to right, and opens d the superior mesenteric vein near its termination.
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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
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n the pancreatico-duodenal area passes upwards in the greater
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entum, lying anteriorly near its free margin, and opens into the tal vein.
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The cystic vein usually ends in the right division of the portal
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n.
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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.
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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
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cisterna chyli.
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Gastric Lymphatic Glands. —These are arranged in two groups, >enor and inferior, the former lying along the lesser curvature of
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stomach, and being almost entirely confined to the left part of this
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'vature, and the latter below and behind the pyloric canal, forming
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subpyloric and retro-pyloric groups. It is noteworthy that there
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no glands in the neighbourhood of the fundus or along the greater vature until the pylorus is reached. They receive their afferent
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'Sels from the stomach, and their efferent vessels pass to the coeliac -nds.
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Pancreatic Glands. —These lie along the superior border of the icreas. They receive their afferent vessels from that organ, and their
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en t vessels pass to the coeliac glands.
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Splenic Glands. —These are numerous, and are situated near the
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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.
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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.
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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.
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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.
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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.
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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.
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The portal vein and its tributaries are destitute of valves, so that blood can regurgitate in cases of portal obstruction.
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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.
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For a description of the bile-duct, see p. 779.
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Fig. 474.— The Portal Vein and its Tributaries (after Spalteholz).
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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
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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
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Fig. 475. — Dissection of the Posterior Abdominal Wall.
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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
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Fig. 476. —The Visceral Areas of the Kidneys. In this case the right renal vein was higher than usual.
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 +
n forwards, is concave, and is connected with the renal vessels and s pelvis of the kidney.
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Relations — Anterior Surface of the Right Kidney. —This surface is erlapped by the right suprarenal gland for a very short distance at
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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
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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.
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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
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Fig. 477. —-Diagram showing the Relations of the Kidneys from Behini
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R.L. Right Lung L L. Left Lung S. Spleen
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R.K. Right Kidney L.K. Left Kidney IX. Ninth Rib X. Tenth Rib
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XI. Eleventh Rib XII. Twelfth Rib
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I. L. First Lumbar Vertebra
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II. L. Second Lumbar Vertebra
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III. L. Third Lumbar Vertebra
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IV. L. Fourth Lumbar Vertebra V.L. Fifth Lumbar Vertebra
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 +
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
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 +
 +
 +
 +
Fig. 478. —Kidney of a Child shortly before Birth.
 +
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 +
 +
 +
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
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 +
 +
 +
 +
c, and (8) median sacral. In what follows, the letter P after an sry signifies parietal, and V visceral.
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 +
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.
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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.
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 +
 +
 +
Fig. 481.—To show the Arrangement of Veins joining to form the Portal Vein, and their Relations to the Aorta.
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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
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 +
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 +
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 +
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.
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 +
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
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 +
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.
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 +
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.
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 +
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)
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 +
 +
 +
 +
 +
 +
 +
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 +
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 +
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:
 +
 +
# Rectum.
 +
# Pelvic colon.
 +
# Descending colon.
 +
# Transverse colon.
 +
# Ascending colon.
 +
# Caecum.
 +
# Vermiform appendix.
 +
# Small intestine.
 +
# Stomach.
 +
# Liver.
 +
# Pancreas.
 +
# Spleen, glands.
 +
# Juxta-aortic
 +
 +
The coeliac glands more particularly receive their chief afferent vessels from the following glands:
 +
 +
# Gastric glands.
 +
# Retro-pyloric glands.
 +
# Hepatic glands.
 +
# Splenic glands.
 +
# 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:
 +
 +
# Common iliac glands.
 +
# Testis. 5. Kidney.
 +
# Ovary, uterine tube, and adjacent half of body of uterus.
 +
# Suprarenal gland.
 +
# Kidney.
 +
# Abdominal wall.
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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.
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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
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e to form a single trunk, called the intestinal lymphatic trunk , which
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is into the cisterna chyli.
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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.
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T nsertion. —The central tendon on all sides.
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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.
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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
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superior epigastric of the internal mammary of each side; and (4) bram from the lower intercostal arteries.
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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
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Fig. 483. —The Diaphragm (Inferior View).
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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.
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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;
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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
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last, which is fixed by the quadratus lumborum muscle.
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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
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smaller, shorter, and more posterior of the two. Each crus is fleshy laterally,
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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.
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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.
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The diaphragm presents three foramina—namely, aortic, vena val, and oesophageal.
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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.
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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.
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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
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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.
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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
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Fig. 484.— The Diaphragm (Superior View) (after L. Testut’s ‘ Anatomie Humaine ’).
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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
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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.
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Development. — The diaphragm is developed in four parts—ventral and dorsal l lateral (R. and L.).
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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
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Fig. 485. — The Thoracic Duct, Azygos Veins, and Posterior Intercostal Glands.
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hes, from which the secondary pleurae will start their extension into the 7-wall.
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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 caud