Book - Handbook of Pathological Anatomy 2.8

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Meckel JF. Handbook of Pathological Anatomy (Handbuch der pathologischen Anatomie) Vol. 2. (1812) Leipzig.

Ligaments: I. Trunk | II. Head | III. Extremities   Muscles: I. Trunk | II. Head | III. Extremities   Angiology: I. Heart | II. Body or Aorta Arteries | III. Body Veins| IV. Pulmonary Artery | V. Pulmonary Veins | VI. Lymphatic System | VII. A Comparison of Vascular System   Nervous System: I. Central Nervous System

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This historic 1812 textbook by J. F. Meckel, Professor of Anatomy at Halle, was translated firstly from German Into French (with additions and notes) by Prof. A. J. L. Jourdan and G. Breschet. Then translated again from French into English (with notes) by A. Sidney Doane. Modern Notes: tendon Musculoskeletal Links: Introduction | mesoderm | somitogenesis | limb | cartilage | bone | bone timeline | bone marrow | shoulder | pelvis | axial skeleton | skull | joint | skeletal muscle | muscle timeline | tendon | diaphragm | Lecture - Musculoskeletal | Lecture Movie | musculoskeletal abnormalities | limb abnormalities | developmental hip dysplasia | cartilage histology | bone histology | Skeletal Muscle Histology | Category:Musculoskeletal Historic Embryology - Musculoskeletal   1853 Bone | 1885 Sphenoid | 1902 - Pubo-femoral Region | Spinal Column and Back | Body Segmentation | Cranium | Body Wall, Ribs, and Sternum | Limbs | 1901 - Limbs | 1902 - Arm Development | 1906 Human Embryo Ossification | 1906 Lower limb Nerves and Muscle | 1907 - Muscular System | Skeleton and Limbs | 1908 Vertebra | 1908 Cervical Vertebra | 1909 Mandible | 1910 - Skeleton and Connective Tissues | Muscular System | Coelom and Diaphragm | 1913 Clavicle | 1920 Clavicle | 1921 - External body form | Connective tissues and skeletal | Muscular | Diaphragm | 1929 Rat Somite | 1932 Pelvis | 1940 Synovial Joints | 1943 Human Embryonic, Fetal and Circumnatal Skeleton | 1947 Joints | 1949 Cartilage and Bone | 1957 Chondrification Hands and Feet | 1968 Knee

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Section II. Arteries of the Body or of the System of the Aorta

Chapter I. General Explanation of the Situation of the Trunk

§ 1328. The aorta arises most generally and with but few excep • tions by one single stem from the upper part of the left ventricle. At its origin the fibrous membrane is much thinner than in the rest of its extent ; but it is not entirely destitute of this membrane, the thinness of which is supplied by the muscular fibres of the heart, which extend some lines over the valves of the aorta, and the triangular spaces which exist between them. At its base are three sinuses, which correspond to the valves. It goes to the right, first its right side, and then the whole artery passing behind the pulmonary artery, which covers its origin : it comes afterwards on the right side of this artery, and describes a curve before the vertebral column, which is called its urch ( arcus aortÅ“). The transverse portion of this arch, the part between the right and left sides, is situated opposite the third and fourth dorsal vertebræ.

At the origin of the arch the aorta is entirely inclosed in the pericardium ; but it gradually leaves this membranous sac ; so that most of the arch is entirely loose. We observe on the left the pulmonary artery, which proceeds along the lower part of the arch of the aorta, behind it the right branch of this artery, on the right the vena cava superior, and in front the sternum.

In old age, the lower and ascending part of the arch of the aorta is more or less dilated : it does not form a perfect cylinder ; but it advances farther and projects more to the right than in early life. This change probably depends on a mechanical cause, — the continual impulse of the blood.

The central part of the arch of the aorta is situated before the lower extremity of the trachea, and the curve terminates behind the left branch of the pulmonary artery and the bronchia of the same side, in which place the direction of the artery changes and proceeds from above down â–  ward.

The ascending part of the arch is situated on the right of the vertebral column, the transverse portion directly before it and the descending portion on the left : the latter is situated in the posterior mediastinum.

The trunk of the aorta remains on the left of the vertebral column in all its extent.

The ascending portion of the aorta in the cavity of the thorax, called the thoracic aorta ( aorta thoracica ), is directly covered on the left by the inner wall of the left pleura, on the right by the esophagus, and forward first by the left bronchia, then by the posterior part of the pericardium.

At the diaphragm the aorta separates from the esophagus behind, passes through a special openingin this muscle ( hiatus aorticus)(§ 1072), comes into the abdomen, and is called the abdominal aorta ( aorta abdominalis). The latter descends as far as the fourth or fifth lumbar vertebra, where it divides into two branches. It is attended on the right by the vena cava inferior, rests behind on the lumbar vertebrae, and is covered both before and on the left by the peritoneum.

Above and below, it divides in an analogous but not in the same manner, since it gives off, 1st, at its two extremities, the vessels which go to the extremities ; 2d, and besides, at the upper extremity, the carotid arteries ; 3d, at the lower extremity those which supply the pelvic viscera with blood.

The vessels of the thoracic and abdominal viscera, and most of those which are distributed to the parietes of the thorax and abdomen, arise directly from the part between its two extremities.

That part of the aorta between its origin from the heart and that of the left subclavian artery (§ 1335), is called the ascending aorta ( aorta ascendens ), the remaining, the descending aorta ( aorta descendens).

§ 1329. The aorta rarely varies from this general arrangement. Nevertheless it may, in the following modes :(1)

1st. The slightest aberration is when the aorta goes backward too soon, passing immediately on the right bronchia.

Then it sometimes reaches the left side, gliding behind the esophagus and the trachea, as we have observed ;(2) sometimes it remains on the right in a greater or less extent of the vertebral column, for instance, to the base of the chest.

This anomaly may be considered as the first degree of the lateral inversion of the aorta, in which its arch curves more or less from left to right instead of describing its usual curve from right to left.

The arteries which arise from it are also modified in a similar manner ; for we sometimes find four trunks ; sometimes an innominata trunk exists on the left side and two other trunks on the right.

2d. The anomaly is greater when the trunk of the aorta tends to divide. This deviation of formation presents several degrees.

(1) O. Bernard, IHss. de arteriarum e corde prodeuntium aberrationibus , Berlin, 1818.

(2) This anomaly has been seen also by Abernethy (Phil, trans., 1793, p. 59-63)j and twice by Caillot (Bullet, de l’Ec. de Med., 1807, p. 21-28).

Sometimes the aorta is single at its origin ; but, some inches farther, it divides into two trunks, which pass one before, the other behind, the trachea, and afterwards unite to give rise to the descending aorta, forming in this manner a ring around the air passage. Hommell has described a curious case of this kind.

б. A greater degree of this deviation of formation exists as in the case reported by Malacarne.( 1 ) In fact the aorta is single at its origin ; but from this point even, its increased size, its oval form, and its five valves, indicate a division which occurs almost immediately. The two branches on the right and on the left give off, first the subclavian, then the external carotid, and finally the internal carotid, artery , they remain distinct from each other for about four inches, and then they unite to form the descending aorta.

This division of the largest artery of the body is curious in this respect, that it is evidently a repetition of the formation of reptiles, a class of animals in the different orders of which these anomalies constitute the normal state. It leads also to the third kind of anomaly.

3d. In this species of anomaly there is no arch. The aorta divides at its origin into two trunks, one right and ascending, which produces the subclavian and carotid arteries ; the other descends and is the pectoral and abdominal aorta. (2)

§ 1330. The aorta presents anomalies not only at its origin, but also in the rest of its course. Thus, the lower extremity of the arch is sometimes very much contracted(3) or entirely closed(4) in a slight extent ; and although the artery does not divide in this place into two large trunks, the circulation however continues by collateral vessels, which are very much enlarged.

Similar anomalies are observed also, but less frequently, in the lower part of the aorta. Thus sometimes the artery bifurcates higher than usual, to give rise to the primitive iliac arteries, which, before they divide into two large trunks, communicate by a transverse branch. (5)

Chapter II. Arch of the Aorta

§ 1331. From the arch of the aorta, or from the ascending aorta, arise first, the coronary arteries of the heart ; next, at a certain distance from them, the arteries of the upper extremities and of the head, which come from its upper and transverse part.

(1) Osserv. di chirurgia, vol. ii. p. 119, tab. i. f. 1, 2. — Auctuarium obs. et. icon, ad ostcol. Padua, 1801, tab. iii.

(2) Abhandlungen der Joseph. Akademie , p. 1. tab. vi.

(3) Paris, in Desault, Journ. de. chir., vol. ii. p. 107, 110.

(4) Steidele, Sammlung chirurgischer Beobachtungen , vol. ii. p. 114, 116. — Graham, in the Alcd. chir. trans., vol. v. no. xx. — Cooper, in Farre, loc. cit., p. 14.

15) Pctsche, Sijllog. obs. anat. select ., § 77.

1. Coronary Arteries of the Heart

§ 1332. The coronary arteries («Æ. coronariÅ“, cardiacÅ“) arise directly above the origin of the aorta, and normally above the upper edge of the semilunar valves, so that their orifices, which correspond to the central part of these valves, are not closed when these valves are pressed against the parietesof the aorta. There are usually two, and not unfrequently three ; the third, which is generally smaller than the others, then arises, not above a special valve, but above and very near one of those to which the other two correspond. We once have found four coronary arteries, of which the two supernumerary arte* ries were much smaller than the others, and only branches prematurely detached from them.

A single coronary artery is much more rare. We have seen this anomaly which however is indicated by the less distance between the origins of the two arteries in some subjects, or in the extreme smallness of one of these vessels, the branches of which are entirely replaced by those of the other.(l) The existence of one coronary artery is curious, as it establishes a relation with the normal formation of the elephant.

But however this may be, each ventricle has a coronary artery which almost exactly corresponds to it.

§ 1333. The right , upper , or anterior coronary artery (A. coronaria anterior , s. inferior , s. dextra) is generally but a very little larger and rarely smaller than the left. It arises from the anterior part of the aorta, above the anterior valve, passes under the pulmonary artery, between the upper part of the right ventricle and the right auricle, being covered by the latter, goes forward to the right, and downward in the groove at the base of the heart, turns around the pulmonaiy auricle, and thus arrives at the lower face of the heart, and terminates in the inferior groove of its septum.

In its course it gives off at right angles, both on the right and left sides, several branches, which are often very much curved.

The right branches are smaller and are distributed to the right auricle ; the left, which are larger, go to the right ventricle, and descend longitudinally on its surface to its apex.

The longest of these descends in the inferior groove of the septum., where it anastomoses by several branches with the left coronary artery.

Other ramifications always exist, which are smaller, and are distributed on the anterior part of the left ventricle, and also communuicate with those of the left coronary artery on the flat side of tue heart.

(1) Barclay (foe. cit., p. 6) has seen the right coronary artery so small thafPit did not extend to the left as far as the septum, and was replap^d o.a this sjde by the transverse branch of the left coronary artery.

This artery belongs principally to the right half of the heart.

§ 1334 . The left, tipper, ox posterior coronary artery (Jl. coronaria sinistra, s. superior, s. posterior ) is generally smaller than the preceding, and arises between the left auricle and the posterior side of the pulmonary artery, almost always above the left sigmoid valve. It descends on the left, between the auricle and the pulmonary artery, and having attained the groove at the base of the heart divides into two or three larger branches.

Of these one, which is anterior and longitudinal, soon separates into several considerable branches, and descends along the upper groove of the septum to the apex of the heart. In its whole course it gives off branches which anastomose with those of the right coronary artery on the upper face of the right ventricle. Some of the large branches which come from it are distributed on the upper face of the left ventricle.

The second branch, which is transverse, goes backward in the groove at the base of the heart, below the left auricle, and gives several branches, which go to the upper face of the left ventricle. The largest descend along the smooth posterior edge of the heart, some on its upper and others on its lower face.

Finally, the left coronary artery terminates by several small branches, which disappear on the lower face of the left ventricle.

These ramifications, like the preceding, anastomose with the other branches of the left coronary artery and with those of the right which meet them.

2. Of the Arrangement of the Large Trunks which arise from the Upper Part of the Arch of the Aorta

§ 1335 . From the upper transverse part of the arch of the aorta arise the trunks which carry the blood to the head, the neck, the upper and anterior .part of the chest, the upper extremities, and partly to the pericardium, the mammary glands, and the lungs.

There are usually three trunks, which arise a few lines distant from each other, the common trunk, or the innominata artery ( iruncus com munis, s. innominatus) , from whence arise the right subclavian and the right carotid arteries, the left subclavian and the left carotid arteries. The innominata artery is situated farther to the right and in front of the others ; the left carotid artery in the centre and a little farther back ; finally, the left subclavian artery most on the left and farther back than the other two.

After birth, the origin of the left subclavian artery sometimes but not always occupies the highest part of the arch of the aorta, while in the fetus it arises the lowest. So likewise in the fetus the innominata artery occupies the highest part of the arch of the aorta.(l) The innominata artery, in ascending from left to right, is situated in front of the trachea. It is separated from the vertebral column by the longus colli muscle, and from the sternum by the sterno-thyroideus and by the left subclavian artery at its side. It is most generally an inch long, rarely longer : sometimes however it is two inches long, and then the trunk reaches the inferior edge of the thyroid gland.

The left carotid artery arises more perpendicularly on the left side along the trachea.

The right carotid and right subclavian arteries are shorter than the synonymous arteries on the left side.

The diameter of the vessels of the two sides is the same, or at least those of the right side are but. little larger than those on the left.

The innominata artery usually arises at the side of the left carotid artery ; the left subclavian artery arises from the aorta, at some distance from the latter ; but the interval between them is not always very great.

The abovementioned arrangement is the most common ; we maythen consider it as the normal arrangement. Frequently however, at least once in eight times, (2) the number of the trunks given off from the arch of the aorta varies. This number may'’ be increased or diminished. In the former case, vessels, which are generally branches, arise directly from the arch of the aorta ; in the latter case, one of the three primitive trunks or frequently all of them are blended with each other and form but one.(3)

(1) Sabatier first pointed out this difference. (See his Memoire, sur les ehavgeniens qui arrivent aux organes de la circulation du fÅ“tus lorsqu’il a commence à respirer ; in the Mem de l’Institut ; sc. phys. et math., vol. iii. p. 342.) We are however satisfied, by numerous observations, that it is not by any means constant. Thus most anatomists have disregarded it. Portal even asserts the contrary ( loc . cit., p. 185), for he states “that the trunk of the left subclavian artery opens into the aorta a little lower than the other two trunks.”

(2) Bichat’s assertion that “the arrangement of these arteries is but slightly subject to variation” is incorrect. Haller makes almostthe same statement, and with no more foundation. Nor is Barclay more correct in asserting that “ the cases are rare where a vertebral artery, a thyroid, a thymic, a pericardiac, or an internal mammary arise from the arch.” Only the anomalies of the internal mam mary artery are rare.

(3) Besides all insulated descriptions of the anomalies in the trunks which arise from the arch of the aorta, we may consult the following works, in which this question has been specially examined, and in a more or less general relation : — BÅ“hmcr, De quatuor et quinque ram is ex arcu aorta: provenientibus, Halle, 1741. — Neubauer, Descriptio anatomica arteriÅ“ innominatÅ“ et thyroideÅ“ imÅ“, Jéna, 1772.— Huber, De arcus aortce ramis ; in the Act. Helvet., vol. viii. p. 68 102. — Walter, Sur les maladies du cÅ“ur ; in the Nouv. Mêm. de Berlin , 1785, p. 57. — Malacarne, Oss. sopra alcune arterie del corpo umano nello stalo prcternaturale e nello stato morboso ; in che Osservaz. di chirurgia, ii. Turin, 1784, p. 119. — Ryan, De quarumd. arteriarum in corp. hum. distrilnitione, Edinburgh. 1810. — Kobenvein, De vasorum d'ecicrsv ahnormi, Wittenberg. 1810,

§ 1336. The number of the primitive trunks is increased more frequently than diminished. Most frequently we find four trunks, one more than the normal number.

This anomaly does not always occur in the same manner.

§ 1337. Our observations on this subject are principally as follow :

1st. Most generally the left vertebral artery, which is normally a branch of the subclavian artery, arises directly from the aorta. This is the most common anomaly. (1). Notwithstanding the abnormal origin of the left vertebral artery from the arch of the aorta, the number of trunks is not increased ; because at the same time the left carotid artery passes to the right and becomes a branch of the innominata artery. This arrangement is remarkable, for it announces an effort tending to bring the anomaly to the normal type of formation.

2d. After this variety, the most common is that where the inferior thyroid artery, or a portion of it, which is always the thyroid portion, arises from the arch of the aorta. This anomaly occurs on the right side more frequently than on the left, and this vessel then arises, lik e the la-ft vertebral artery, between the innominata and the left carotid artery.

Besides these, we sometimes see coming from the arch of the aorta, in no determinate place, and most generally a little before the large trunks, and not on the same hue with them,

3d. A thymic artery (•/?. thy mica), or

4th. An internal mammary artery (Jl. mammaria interna ).

Less frequently, four trunks arise from the aorta, when the right subclavian artery comes directly from the arch of the aorta. We here find many differences.

5th. The right subclavian artery arises farthest to the right, or

(1) Bichat is also incorrect in saying that ihis anomaly is more rare than an increase in the number of the trunks of the aorta by a most inferior thyroid artery. Sabatier goes even farther, for he does not mention it at all, although he states several Other anomalies which increase the primitive trunks of the arch of the aorta (Anat., vol. iii. p. 7). Portal also is silent in regard to it and only mentions the division of the trunk of the innominata among the causes which increase the number of the arteries given off directly by the arch of the aorta (Anat. med., vol. iii. p. 155). In fact, in another place he states that the left vertebral artery arises directly from the aorta ; but he adds, contrary to what is the fact, that this arrangement is very rare. Monro does not mention it when treating of the anomalies of the trunks which arise from the arch of the aorta ( Outlines , vol. iii. p. 276, 278), although he speaks of them when treating of the varieties of the subclavian artery (loc. cit ., p. 301). Soemmerring, on the contrary, very properly seems to regard it as the most frequent anomaly, and mentions it as the first case where four arteries arise from the arch of the aorta. Boyer ( Tr. d’anat., vol. iii. p. 41) asserts, that the origins of the left vertebral and of a most inferior thyroid artery are equally common and just as frequent. It has been asserted that this anomaly was more rare in the south of Germany than that of the origin of the right subclavian artery directly from the aorta. We are satisfied from observation that this is incorrect ; and we cannot agree to it, because other anatomists of great authority, particularly Haller (le. an.fasc. vi. p. 1), Neubauer {loc. cit., p. 287), Scemmerring and Boyer (loc. cit., p. 25), assert exactly the contrary, and it is refuted by comparing tho number of known cases which njcntipn the different anomgjïes în the trunks of the arch .of the aorta..'

6th. This, which is much more common, anses farthest to the left, below the left subclavian artery.

Between these two formations there are several degrees ; for the right subclavian artery arises

7th. Between the right and left carotid arteries ; sometimes 8th. Between the left carotid and the left subclavian artery.

Of these five anomalies, in all of which the right subclavian artery is insulated from the right carotid, the second is undoubtedly the most frequent. When it exists, the right subclavian artery generally passes between the esophagus and the trachea, seldom before the latter, and goes to the right arm.

9th. This division of the innominata artery is sometimes attended with the transposition of both carotid arteries ; so that

10 th. First the left, then the right carotid artery, next the left subclavian artery, and finally the right subclavian artery arise ; or

11th. Both of the carotid arteries and the right subclavian artery arise in their normal places, but the origin of the left subclavian artery is farther to the right.

But the separation of the right subclavian artery from the right carotid does not necessarily increase the number of the trunks ; for then both carotids are usually blended into one trunk, an arrangement to which may be applied our remarks upon the analogous union occurring when the vertebral artery arises directly from the arch of the aorta.

§ 1338. More rarely five trunks arise directly from the arch of the aorta. When this occurs,

12th. The aorta gives off, besides the usual three trunks, the left vertebral artery, and the right internal mammary artery ; (1) or,

13th. It gives off a right inferior thyroid artery, (2) or, the innominata artery divides into the right subclavian and right carotid-artery, the former arising farthest on the right ; and besides,

14th. The left vertebral artery, (3) or the right inferior thyroid artery, (4) arises directly from the aorta ; or,

15th. The right subclavian artery arises below the left, at the same time that the trunk of the innominata is divided into the subclavian and carotid arteries, and that the left vertebral artery arises directly from it. (5) Finally, sometimes, although seldom, instead of three trunks, 16th. We have six.

(1) Bcehmer, loe. cit. ; in Haller, Coll, diss., vol. ii. p. 453.

(2) We have seen this anomaly twice.

(3) Loder, Nonnull, arter. variet., Jéna, 1781.

14) Patsche, in Haller, Coll, diss., vol. vi. § 44.

(5) Kotjerwein, De decursu vasorurn abnorm., Wittenberg, 1813.

The aorta then gives origin to the right subclavian and carotid arteries, separately; the right vertebral artery arises between them, and the left vertebral artery springs directly from the arch of the aorta, between the left carotid and subclavian arteries. (1)

§ 1339. The number of the trunks is diminished in several modes.

I7th. The left carotid artery is a branch of the innominata, or,

18th. It arises by a common trunk with the subclavian artery of the same side ; or,

19th. The first trunk divides into the two carotid arteries, the second into the two subclavian arteries ; or,

20th. The right trunk is the right subclavian artery, the left is the common trunk of the left subclavian and the two carotid arteries.

The last anomalies are as rare, as the first is common. Our observations have proved that the latter and the distinct origin of the left vertebral artery, are the most common.

§ 1340. Sometimes, when the number of the trunks is neither increased nor diminished, their arrangement varies from the normal state. Abnormal unions and divisions then exist, of which the principal are

21st. The innominata artery is divided, but the two carotids arise by a common trunk, which is implanted in the arch of the aorta, between the two subclavian arteries.

22d. The innominata artery is divided, on the right side into the subclavian and carotid arteries ; but on the left side, both of these arteries arise by a common trunk. The preceding formation leads then to a total inversion of the origin of the vessels.

23d. The innominata artery is divided, but we find a common trunk for both carotid arteries, and 2d, one for the left, and 3d„ one [for the right subclavian artery, which then arises farther from the left side than usual, most generally below the left, and goes to the right upper extremity, passing before or behind the trachea, and most commonly the esophagus.

24th. The innominata artery also gives off, besides its usual branches, the left carotid artery ; but the left vertebral artery then arises directly from the arch of the aorta, between the other two trunks.

§ 1341 . Finally, the least possible anomaly is where only the relative situations of the larger trunks which come from the arch of the aorta are changed : they are,

1st. The trunks arise uncommonly near each other. The left carotid artery then most generally approaches the innominata. This anomaly makes the transition to the union of the two carotids into one. Again, but more rarely, the left carotid artery separates from the innominata, while the left subclavian artery approaches it. This anomaly leads to another case which is rarer, where the left carotid and left subclavian arteries arise by a common trunk.

(1) This anomaly has been seen by F. Muller, formerly demonstrator at Copen baffen, who communicated it to me.

Sometimes also the three trunks are so near each other, that they in fact arise from the same surface, or form but one stem. This anomaly evidently makes the transition to that where the aorta divides, directly after its origin, into an ascending and a descending trunk.

2d. The distance between the origin of the trunks is sometimes unusually great. Thus we have found in a child two years old, the left carotid artery nearly an inch distant from the innominata ; the left subclavian artery was also nearly an inch from the left carotid ; the arch of the aorta was extremely sharp, and the left carotid artery arose from the angle formed by the union of the right and left portions.

3. Primitive Carotid Artery

§ 1342. The primitive or common carotid artery ( Carotis primitiva s. cephalica ) ascends along the trachea, which generally separates that of the right and left sides. It usually extends to the upper extremity of the larynx, where it bifurcates, at some distance from the angle of the lower jaw, and seldom behind it. It is situated very superficially, especially its central part, so that it is most easily found there. It is covered before by the sterno-cleido-mastoideus, the sterno-hyoideus and the omo-hyoideus muscles ; the internal jugular vein and the pneumogastric nerve are on the outside, and a little in front of it ; the latter is situated between the two vessels ; inside are the trachea, the larynx, the thyroid gland, and also the esophagus ; behind it is the cervical portion of the great sympathetic nerve, the longus colli and rectus capitis major muscles, and the inferior thyroid artery, which separate it from the vertebral column. The inferior thyroid artery seldom passes before it. The primitive carotids are generally situated on the two sides of the trachea, the right a little more forward than the left ; but sometimes, particularly at their lower parts, they are placed somewhat before this canal. The right carotid artery assumes this arrangement, especially when the innominata arises unusually far on the left, and the left when it arises from this trunk. In both cases the arteries cross the interior face of the trachea. These anomalies should be known, as they endanger the carotid arteries in the operation of tracheotomy.

The primitive carotid is inclosed with the internal jugular vein and the pneumogastric nerve, in a very firm cellular sheath.

§ 1343. From the primitive carotid artery arise only small and inconstant vessels, which go to the surrounding parts, but sometimes, and not unfrequently, it gives off, especially on the right side, the superior or the inferior thyroid artery, either wholly or partially ; the latter is more common. The origin of the inferior is, in this case, towards the lower part ; that of the upper, near the upper end of the artery.

§ 1344. The common carotid artery divides, generally as hign ass the upper edge of the thyroid cartilage, into two branches, one of which, the internal carotid, supplies the brain and the eye, while the other, the external carotid, belongs to the upper part of the neck, the skull and the face. It sometimes bifurcates much higher up, opposite the upper extremity of the styloid process, but not till it has given off the larger of the longer branches of the external carotid.(l) This arrangement is very analagous to that where the primitive trunk does not divide into two large branches, but having given off the branches of the external carotid artery. (2) This anomaly consists evidently in the premature division of the trunk, while its branches are given off too soon. In some few cases the division extends much farther, and attains even the trunk of the primitive carotid. This trunk then begins to divide very soon, and it sometimes bifurcates, opposite the sixth cervical vertebra, but the two branches remain connected with each other.(3)

The distance between the place of bifurcation and the thyroid cartilage is the same at all periods of life : (4) but the distance between the bifurcation and the angle of the lower jaw is much greater in the child than in the adult, on account of the development of the teeth, so that during early life the two large inferior branches are loose for some distance.

These two branches ascend almost perpendicularly. Below they are situated directly at the side of each other. The internal is at first more superficial than the external carotid, but it afterwards becomes deeper. Their proportional volume is not always the same. The differences depend partly on the age, partly on the distribution of the external carotid artery.

In the first respect, the internal carotid artery is always larger than the external in infancy, on account of the size of the brain : in the second, the external is larger than the internal carotid in the adult, when it gives off the superior thyroid artery, and smaller than it, on the contrary, when the latter comes from the prmitive carotid.

I. EXTERNAL CAROTID ARTERY.

§ 1345. The external carotid artery ( Carotis externa, s. facialis, s. A. p encephalic a) ascends under the posterior belly of the digastricus muscle of the lower jaw, is situated between the ear and the ascending branch of the lower jaw, where it is entirely covered by the parotid gland, and divides at the neck of the lower jaw into a superficial branch, which is the temporal artery, (Jl. temporalis ) and a deeper seated branch, the internal maxillary artery. ( A . maxillaris interna.) But it always gives off large branches, before it bifurcates. These branches generally detach themselves gradually, one after another. Sometimes, however, the external carotid artery forms a short trunk, which divides directly above the bifurcation of the primitive carotid into the large inferior branches, and the broad continuation of the trunk.

(1) Burns, Surgical anatomy, Edinburgh, 1811, p. 95, 96.

(2) Idem, ibid., p. 95.

(3) Idem, ibid., same page. — We regret that the author does not say whether the anomaly existed on the two sides or only on one side, (perhaps the left';)

(4) Idem, ibid., p. 379.

§ 1346. Before bifurcating, the external carotid artery gives off branches principally in three directions : forward, backward, and inward.

A. ANTERIOR BRANCHES.

§ 1347. The anterior branches are the superior thyroid artery, thtr lingual artery, and the facial artery.

1. SUPERIOR THYROID ARTERY.

§ 1348. The superior thyroid artery (A. thyroidea superior) is the lowest branch of the external carotid artery. Its origin varies : it geneerally arises some lines above the bifurcation of the primitive carotid ; but it not unfrequently detaches itself at the bifurcation, or below, and even from the trunk of the primitive carotid ; sometimes an inch below its bifurcation.

Its size also varies, and it is in the inverse ratio of that of the inferior thyroid artery. When the latter is entirely deficient, the superior is much larger than usual ; it is on the contrary very small, when the inferior thyroid artery is very large, or when the lowest thyroid artery exists.

Sometimes, but unfrequently, it arises by a common trunk, with the lingual artery, and in some subjects this trunk comes from the primitive carotid.

On the other hand, we not unfrequently find the superior thyroid artery double, because the branches which it generally gives off are detached lower than usual. The arrangement and size of the left and right thyroid arteries vary ; sometimes one of them is deficient, while the other is very large.

§ 1349. When the artery does not arise much lower than usual, nor from the primitive carotid, it always descends inward and forward, being at first slightly concave above, and very tortuous. It sometimes gives off a large branch immediately after arising, which detaches itself from its posterior and inferior part, and goes to the sterno-cleidomastoideus muscle. It then soon divides into an upper and a lower branch. Sometimes it bifurcates near or even at its origin.

The upper or laryngeal branch (ramus laryngÅ“us ) arises from the external carotid artery, according to our observations, once in eight tim<^. It goes downward, forward and inward, on the thyroid cartilage, and frequently gives branches to the omo-hyoideus,the sterno-hyoideus, the stevno-thyroideus, the hyo-thjuoideus and the cvico-thvroidcits muscles, which come sometimes from the lower branch, or directly from the external carotid artery : furnishes a large anastomotic vessel which goes across the cricoid cartilage, and unites with the branch given off by the synonymous artery opposite ; finally it penetrates within the larynx, passing generally between the hyoid bone and the thyroid cartilage, sometimes, but more rarely, near the upper edge of the latter, by an opening which exists there, or even between the cricoid and the thyroid cartilages.(l) Having arrived at this organ, it distributes itself upon its internal membrane, and also to its muscles, anastomoses very frequently with the synonymous artery of the opposite side, and even sends ramuscules outside of the larynx, which communicate on its surface with those of the other side, and with the ramifications of the thyroid branch.

The inferior or thyroid branch ( R. thyroideus ) is the continuation of the trunk ; it sometimes furnishes many or even all the muscular branches which we have described as coming from the laryngeal branch ; but small twigs always arise from it and go to the middle and inferior constrictors of the pharynx and to the crico-thyroideus muscle. After which it descends downward into the thyroid gland, and generally divides, at its upper extremity, into two branches, a posterior and inferior, and an anterior and superior, which soon subdivide. The former penetrates posteriorly into the thyroid gland, and anastomoses along its posterior face with the branches of the inferior thyroid artery ; the other proceeds along its upper edge, gives off considerable branches which expand on its anterior face, and anastomose, by very large vessels, with the synonymous branch of the opposite side.

When the superior thyroid artery is divided into two separate trunks it often happens, but not always, as one might think from what several anatomists say, (2) that the laryngeal branch is distinct from the thyroid branch, and situated above it. Sometimes however, but very rarely, the superior thyroid artery gives off only the trunk of the muscular branches and the laryngeal branch.

II. LINGUAL ARTERY.

§ 1350. The second branch is the lingual artery (v3. lingualis, s. sublingualis, s. ranina), which arises farther inward, most generally a few lines, and sometimes an inch, above the preceding, and rarely by a trunk in common with the superior thyroid artery, but more frequently, and nearly once in seven times, with the facial artery. It is generally a little larger than that we have mentioned.

(1) We have remarked that this is the most common arrangement ; so that our observations in this respect agree with those of Mayer (toe. cit., p, 249), and with Bichat ( loc . cit., p. 149), who both say that the laryngeal branch commonly penetrates into the larynx by passing between the hyoid bone and the thyroid cartilage. Murray (loc. cit.. p. 11) indicates exactly these three arrangements, but does not say that the first is the most frequent. Scemmerring (p. 131) entirely neglects this, and speaks only of the two which are less frequent. Sabatier (p. 115) mentions only the third.

(2) Mayer, (loc. cit., p. 49) asserts, but wrongly, that the laryngeal always arises a quarter of an inch above the thyroid artery. Sabatier (loc. cit., p. 15) ; Soemmering (loc. cit., p. 131); (Portal, foe, cit., p. 159).

This artery curves considerably, and its convex part looks upward, passes then directly over the large horn of the hyoid bone, goes horizontally forward, glides between the middle constrictor of the pharynx and the hyoglossus muscle, and then ascends towards the base of the tongue, where it recommences, and then goes horizontally forward, along the inferior face of this organ.

From its posterior part arise, 1st, several branches, which go to the hyo-glossus muscle and middle constrictor of the pharynx, and which, having passed through the latter, enter the digastiicus and the thyrohyoideus muscles, and the submaxillarv gland ; 2d, a branch which goes downward and inward, between the genio-glossus and the geniohyoideus muscles directly on the hyoid bone, gives branches to these muscles, especially to the first, and anastomoses with that of the opposite side. It is called the hyoid branch (I?, hyoideus).

From the central ascending part aiise one or more dorsal arteries of the tongue ( ll dorsales linguae ), which go downward to the posterior part of the tongue, on the inside of the hyo-glossus muscle, ascend upon the back of this organ, and advance to the epiglottis.

The lingual artery divides, in front of the hyo-glossus muscle, into a ranine and a sublingual artery.

The ranine artery (A. ranina) is larger than the other, and is a continuation of the trunk. It extends deeply between the lingualis and genio-glossus muscles, proceeds forward, gives off several branches in its course, and finally anastomoses with that of the opposite side, behind the summit of the tongue, at the upper end of its frenum.

The sublingual artery (A. sublingualis ) is more external and more superficial than the preceding. It passes over the mjdo-glossus muscle, between it and the sublingual gland, gives off branches to it, to the hyo-glossus muscle, to the lingualis muscle, and to the proper membrane of the mouth, passes over the mylo-hyoideus muscle, and anastomoses with the inferior maxillary branch of the facial artery.

This artery sometimes arises from the facial.

III. FACIAL ARTERV.

§1351. The third branch, the facial or external maxillary artery [A. facialis , facialis anterior, angularis, maxillaris externa), varies in respect to its origin, size, and extent ; it is commonly the largest of the three anterior branches of the external carotid, and supplies all the anterior part of the face ; but sometimes also it extends only to the angle of the mouth, and the other branches are supplied from the temporal artery. There is scarcely a vessel which varies so much asihis. even in the two sides of the same body.

It passes under the posterior belly of the digastricus muscle to go to the angle of the lower jaw. In this place it proceeds first horizontally behind and within the inferior edge of the lower jaw, then goes obliquely upward and forward on the inside of this bone and of the upper jaw.

It frequently gives of!’, directly above its origin, the inferior or ascending palatine artery (Ji. palatina ascendens , s. inferior ), which usually arises from the ascending or inferior pharyngeal artery (A. pkanjngÅ“a ascendens) ; we shall describe it with that.

It then gives small ramuscules to the digastricus and stylo-hyoideus muscles.

Farther on, it gives off considerable branches which go to the submaxillary gland ( R . glandular es), and goes forward in one of its grooves. Farther onward, it gives off one or more ramuscules to the pterygoideus internus muscle.

It then furnishes the submental artery ( R . submenlalis). This arises near the lower edge of the lower jaw, and proceeds along it, directly below the attachment of the mylo hyoideus muscle, and over the anterior belly of the digastricus muscle, gives ramuscules to both of these muscles, anastomoses with the sublingual artery, and thus goes forward, where it communicates with that of the opposite side, on the centre of the lower edge of the lower jaw. Thence it reascends into the substance of the lower lip, to which it gives twigs, as also to the skin of the chin, and anastomoses with the descending branches of the coronary artery of the lower lip, and also with those of the inferior dentar artery, which emerges from the mental foramen.

When the sublingual artery is a branch of the facial it arises a little, and even in most cases directly before the submental.

The continuation of the trunk, or the proper facial artery, turns upon the lower edge of the lower jaw, generally directly before the anterior edge of its ascending branch, thus attains the outer face of this bone, descends very obliquely between the masseter and the triangularis oris muscles, arrives at the angle of the lips, and gives off in this place several branches, which enter the masseter, the triangularis and the buccinator muscles and the skin.

About the centre of the space between the angle of the mouth and the under edge of the lower jaw, it generally divides into two branches. One, the continuation of the trunk, goes directly upward ; the other is smaller, and proceeds more obliquely inward and forward.

The latter is the inferior coronary artery of the Up {A. coronaria labii inferioris). It passes under the triangularis oris muscle and proceeds toward the lower lip, gives several branches to this muscle, to the levator menti, and also to the membrane of the mouth, and anastomoses both with its fellow of the opposite side and with the twigs of the submental and inferior dentar artery.

This artery is sometimes much smaller on one side than on the other. In some subjects it is even entirely deficient, and is then replaced bv that of the opposite side. Sometimes it arises much higher and comes from the superior coronary artery of the lip. In some cases it is double : one of the two then arises much above the other ; but the two arteries taken together are not larger than that of the opposite side : sometimes the two branches into which the lower coronary artery of the lips is divided are very small.

After giving off this branch, the facial artery winds tortuously upward and inward. Arrived as high as the angle of the mouth, it generally divides, a little above this point, into two branches.

The larger goes inward and forward, between the fibres of the orbicularis oris, and is called the superior coronary artery {A. coronaria labii superioris). This artery proceeds directly over the loose edge of the upper lip, gives ramuscules to the orbicularis oris, to the levator labii superioris, to the skin, to the buccal membrane, meets that of the opposite side and anastomoses with it by a broad communication similar to that between the inferior coronary arteries. The two coronary arteries usually anastomose together in two places by large branches : sometimes the anastomosis between the arteries is very small on one side, but is replaced by a very large branch, which arises higher up from the facial and which communicates with the artery of the septum of the nose.

Both coronary arteries are very tortuous, but the upper is more so than the lower. Both anastomose with the synonymous arteries of the opposite side, and these anastomoses are proportionally the largest in the body, when we consider the vessels between which they occur.

The superior coronary artery always gives off from its centre, where it anastomoses with that of the opposite side, a branch, which goes upward toward the nasal septum, which is called the artery of the septum of the nose {A. nasalis septi). Sometimes this artery is single, sometimes double, and even triple, at its origin : in the last two cases-it is frequently given off by the coronary artery of one side ; but however this may be, it divides near the septum of the nasal fossae into at least two branches, a right and a left, each of which proceeds along the lower edge of the septum and the inner part of the corresponding nostril to the end of the nose, and also sends ramuscules, which reascend on the cartilaginous septum.

Besides these branches, the coronary artery gives off sometimes before, more externally and on one side only, or on both, another considerable branch (R. pinnalis), which goes to the ala and the outer part of the nostril ; but this branch more frequently comes from the next one.

The facial artery, after giving off the superior coronary, consists only of a smaller branch, which may be called the common external nasal artery (A. nasalis externa communis). This artery is very tortuous, and ascends obliquely forward under the levator labii superioris muscles, to which it gives ramuscules, goes toward the nose, and anastomoses by considerable branches with the infra-orbitar artery. It usually gives off, opposite the nostril, the lateral arteries of the nose ( R . pinnules , s. laterales nasi), and also sends off numerous smaller arterial twigs, which anastomose with each other and also with those of the septum and their corresponding ones of the opposite side, which are called the dorsal arteries (R. nasales dorsales ), and which always communicate on the nose by several large or small branches with the ophthalmic artery. Finally, it terminates on the back and side of the nose, and never, even in its greatest degree of extension, goes beyond the upper edge of the cartilaginous portion of this organ.

The two coronary and the common external nasal artery, and more frequently only the superior coronary and the latter, sometimes arise not only from the above facial but also from the transverse facial artery, which then is much larger, while the other is smaller, although the facial artery is not necessarily more developed at its lower part ; we likewise observe in other subjects that this artery is very much developed at its upper part, although the lower part does not produce more branches than usual. We have seen the sublingual artery coming from it at least several times, and the facial artery at the same time was as large as usual. In other cases, on the contrary, it gives off neither of the two coronary arteries, while the sublingual artery arose as usual ; but the submental artery was uncommonly small.

Hence it appears that the facial artery is always the principal source of communication, 1st, between the superficial and the deep-seated branches of the external carotid by its anastomoses with the infra-orbitar, the nasal, and the dentar arteries ; 2d, between the external and the internal carotid arteries by its anastomosing with the ophthalmic artery.

§ 1352. Numerous small branches, which go to the masseter and pterygoidei muscles and to the parotid gland (/i. masseterici,pterygoidei , et parotidei ), arise externally and internally from that part of the carotid artery situated between the ascending branch of the lower jaw and the ear.

A larger anterior branch, the transverse facial artery, which will be described hereafter, rarely arises from its upper extremity, directly below its division.

B. INNER BRANCH.

I. ASCENDING OR INFERIOR PHARYNGEAL ARTERY.

§ 1353. Most generally only one branch arises from the inner face of the external carotid artery ; this is the ascending or inferior pharyngeal artery {.Il . pharyngcea ascendens , s. inferior , s. posterior ), which comes sometimes from the bifurcation of the primitive carotid, somerimes from the origin of the internal carotid, but more frequently from the occipital artery, (1) and is sometimes replaced by the branches of the facial artery.

If it is a branch of the external carotid, it arises very deeply, most generally above the inferior thyroid artery ; so that it is the second branch from the trunk . but sometimes it comes higher up and even above the facial artery.(2)

It is sometimes double : then the two inferior pharyngeal arteries rarely come from the external carotid ; one arises from the latter, and the other from one of the secondary branches above described, or from the internal carotid artery. (3)

It is always the smallest branch of the external carotid artery.

It goes perpendicularly upward, on the inside of the external carotid artery, and in the same direction with it, between it and the pharynx.

It gives off first the descending branches to the constrictors of the pharynx, and to the anterior and lateral muscles of the neck.

A little farther it divides into two branches, one of which, the pharyngeal branch, (R. pharyngÅ“us ) is distributed principally to the constrictors of the pharynx, and communicates with the pharyngeal branches of the superior thyroid artery ; the other is termed the posterior meningeal artery, («d. meningÅ“a posterior ) ascends through the posterior foramen lacerum of the skull, or through a special opening near the occipital condyle, and is distributed to that part of the dura mater which lines the lower part of the skull.

C. POSTERIOR BRANCHES.

§ 1354. The posterior branches of the external carotid artery are, 1st the occipital , and 2d the posterior auricular artery.

1. OCCIPITAL ARTERY.

§ 1355. The occipital artery («3. occipitalis) is a considerable branch, but much smaller than the three anterior branches, which usually arise opposite the lingual or the facial artery ; seldom or never above or below them. It rarely comes from the internal carotid artery. It is very deeply situated ; goes upward and backward, often gives off, soon after arising, branches which go to the posterior belly of the digastricus muscle of the lower jaw, then a descending branch, which goes to the sterno-cleido-mastoideus muscle and the upper lymphatic glands of the neck, higher up, gives off wholly or partially the ascending pharyngeal artery, then extends below and deeply between the transverse process of the first cervical vertebra and the mastoid process of the temporal bone, continues its course backward, passing under the complexus minor muscle, then assumes a horizontal direction, gives branches to the upper extremity of the sterno-cleido mastoideus, to the complexus minor, to the transversalis colli, to the small lateral and posterior muscles of the head, and then ascends on the occipital bone, covered by the upper part of the splenius muscle, to which it gives branches. It is then called the superficial occipital artery, proceeds directly below the skin, on this bone to the vertex, terminates in a large anastomosis, formed by its branches with each other and with those of the frontal, the superficial temporal and the synonymous artery of the opposite side.

(1) Scemmerring states that it sometimes arises from the superior thyroid arterjL AVe have never seen this, nor is it mentioned by any other anatomist, Scemmerring', it is true, quotes Mayer ; but the laryngo-pharyngean artery ( A . laryngo-pharyvgcea) described by Mayer, is the laryngeal branch of the superior thyroid artery, and describes the inferior pharyngeal artery as the posterior artery of the throat,

(2) Bichat asserts that it arises between the facial and lingual arteries. Our observations lead us to think that SÅ“mmerring is more correct in saying that it rarely arises higher than the lingual. Murray places it behind the facial, but adds that its origin is near that of the lingual. Portal also places it nearly opposite this latter, as do Sabatier and Mayer. Boyer states that it arises opposite the facial.

(3) Scemmering asserts that when it is double, the lower trunk arises from the prim tive carotid, and the superior from the internal carotid. This arrangement exists sometimes, but it is not the law. That mentioned by us is much more common.

At the place where the occipital artery leaves the space between the transverse process of the first cervical vertebra and the mastoid process of the temporal bone, to pass on the obliquus capitis major muscle of the head, it always gives a deep or descending branch. This branch being sometimes very considerable, and nearly as large as the continuation of the trunk, we may then admit that the artery divides at this place into a superficial and deep-seated branch. When this is the case, it descends to the middle of the back, between the splenius, complexus, digastricus and transversalis colli muscles. Sometimes, however, it is very small, and then it is distributed in the small posterior muscles of the head.

The deep-seated branch anastomoses many times with the vertebral artery, and with the cervical branches of the inferior thyroid artery.

From the superficial occipital artery constantly arise one or several branches, which pass into the cranium through the mastoid foramina ; more rarely through the large occipital foramen or the foramen lacerum, which are distributed to the posterior and inferior part of the dura mater. They are termed the posterior meningceal arteries. (A. meningeÅ“ posteriores ab occipitali.)

2. POSTERIOR AURICULAR ARTERY.

§1350. The posterior auricular artery (A. auricular is posterior) is generally much smaller than the preceding, and arises a little above it, in the substance of the parotid gland, and is generally separated from it only by the stylo-hyoidcus muscle. Sometimes it arises from this artery, and rarely somewhat higher, directly below the division of the external carotid artery into the superficial temporal and the internal maxillary artery. It goes upward, at the side and behind the trunk of the external carotid artery, and passes through the parotid gland, near the mastoid process. There it gives, 1st at its lower posterior part, branches which go to this gland, to the posterior belly of the digastricus muscle, to the stylo-hyoideus and to the upper part of the sternocleido-mastoideus muscles ; 2d, from its superior and anterior part, an ascending branch, the stylo-mastoid artery (A. stylo-mast oidea), which furnishes minuscules to the auditory passage, penetrates into the canal of the facial nerve through the stylo-mastoid foramen, distributes itself to the mastoid process, to'the tympanum, and also to a portion of the labyrinth, and anastomoses with a branch of the middle meningeal artery. The trunk of the artery then divides at the level of the mastoid process into two branches, an inferior or muscular and a superior or auricular branch.

The inferior branch goes transversely outward, over the upper part of the splenii muscles, gives minuscules to these muscles, to the trapezius and to the skin, anastomoses with the superficial occipital artery, and advances toward the occiput.

The superior branch goes upward and backward. It usually divides into two or three branches, one of which, the more transverse, goes backward to the mastoid process, and gives branches to it, also to the occipitalis muscle ; while the other, or the others, attain the posterior part of the concha, distribute the small arteries to the retrahentes auriculæ, and to the transversus auriculae muscles, then pass over the concha, and thus come on its internal face, where they lose themselves in the skin and the mucous membrane.

D. TERMINATION OF THE EXTERNAL CAROTID ARTERY.

§ 1357. The external carotid artery terminates at the neck of the lower jaw in two trunks, a superficial, the temporal artery ; the other deep-seated, the internal maxillary artery.

I. TEMPORAL ARTERY.

§ 1358. The temporal artery (A. temporalis) is smaller and more superficial than the internal maxillary, and continues in the direction of the trunk. It goes upward and outward. Its branches may be divided into anterior and posterior.

The anterior branches are principally the following :

1st. The first branch is often the upper masseteric artery (A. masse, terica superior ) which penetrates sometimes to the external and sometimes to the internal layer of the masseter muscle, but frequently comes from the next.

2d. The transverse facial artery (A. transversa , s. transversalis faciei){ 1) is the second, often the first branch of the artery, and arises directly above the bifurcation of the external carotid artery. Sometimes, but unfrequently, it arises from the external carotid artery, and most generally from the bifurcation. It goes forward, with the canal of Stenon, on the masseter muscle, directly below its upper edge, gives off the superior masseteric artery, when this does not come from the temporal artery, sends several minuscules to the skin, penetrates forward into a greater or less portion of the orbicularis palpebrarum muscle, and anastomoses, by a considerable number of ramifications, with the facial artery, which it meets, and with the infra-orbitar artery. Sometimes this gives off all the upper part of the facial artery.

(1) Scemmering ( loc . cit.. p. 196) mentions it as arising from the external carotid artery, before it bifurcates, and says also that it sometimes comes from the internal carotid artery, and cites as authorities Mayer, Murray, and Walter. But Murray states expressly that it is the fourth branch of the external temporal artery (p. 17).

In some subjects its ascending minuscules extend much higher, and reach the outer extremity of the edge of the orbit.

The middle temporal artery ( A . temporalis media) generally arises some lines above the transverse facial artery, a little below the malar bone, a considerable branch, which proceeds first from below upward, gives off one or several minuscules to the upper part of the masseter muscle, then curves backward at a right angle, between the trunk and the temporal muscle, and terminates partly in small twigs, which penetrate into the substance of the muscle where they anastomose with those of the deep temporal artery, and partly in superficial branches, which are distributed on the auditory passage, where they communicate with those of the posterior auricular artery.

After giving off this artery, the trunk of the temporal artery goes upward and forward, on the temporal muscle, directly under the skin, and describes a considerable arch, which is convex posteriorly and terminates as the anterior temporal artery (Jl. temporalis anterior ), anastomosing several times with the superciliary artery, and giving branches to the frontalis muscle, and to the skin of the forehead.

Small inconstant branches come from the anterior and concave part of the arch which it describes, these go forward into the outer part of the orbicularis palpebrarum muscle, and communicate with the ascending branches of the transverse facial, and also with the upper minuscules of the anterior temporal artery.

The posterior branches of the superficial temporal artery are,

1st. The anterior inferior auricular arteries (Jl. auricular es anteriores inferiores ), usually three or four in number, which arise directly above one another from its lower part, and are expanded in the inferior and anterior part of the concha.

2d. The anterior and superior auricular artery {Jl. auricularis anterior superior) which is often single, rarely double ; it arises nearly opposite the preceding branches, and goes to the upper and anterior part of the concha, and to the attollens auriculae muscle.

Mayer describes it as the tenth branch of the external carotid artery (p. 84), but asserts positively that it arises about a line above the internal maxillary artery. The descriptions of Portal (p. 186), Boyer (p. 42), Bichat (p. 152), and Menon (p. 267), agree, like that of Murray, with the results of our observations.

3d. Two or three larger branches usually go backward, inward, and upward, and anastomose with each other and with those of the opposite side, and with the superficial occipital artery, which sometimes partly replaces them. They are called the posterior temporal arteries ( A . temporales posteriores'), and they are usually wrongly considered as forming, in opposition to the anterior temporal artery, but one branch.

II. INTERNAL MAXILLARY ARTERY.

§ 1359. The internal maxillary artery {A. maxillaris interna , A. orbito-maxillaris) is larger than the preceding, but differs more from the direction of the primitive trunk, and is situated more deeply, so that it cannot be seen entirely till the zygomatic arch and the outer part of the body of the upper maxillary bone is removed.

Its direction changes several times in its course. First, it goes transversely inward and a little forward, behind the neck of the jaw ; then it goes directly inward, and passes between the two pterygoidei muscles, or curves again a little forward. Arrived at the pterygoid process, it goes perpendicularly upward, over the pterygoideus extern us muscle, and is reflected on itself as high as the floor of the orbit, so that its direction becomes horizontal. Thence it divides into several branches which descend more or less, by which it terminates, distributing itself on one side on the inner and posterior part of the nose, on the other to the outer part of the face.

Proceeding in this manner, it distributes the blood to the dura mater, to the internal ear, to the pterygoidei muscles, to the temporalis muscle, to the teeth, to the interior part of the nose, to the upper part of the pharynx, and to a part of the face, and communicates with several branches of the external and internal carotid, by the following branches, which are successively given off. It usually sends one or two to the ear, viz :

a. The deep-seated auricular artery (A. auricidaris profunda), which goes to the organ of hearing.

b. The artery of the tympanum (A. tympanic a), which is distributed to the temporo-maxillary articulation, and then penetrates into the cavity of the tympanum, through the fissure of Glaser. These two branches often arise from the external carotid artery, or from the facial or temporal artery.

c. The small meningeal or the external pterygoid artery ( A.meningca parva, s. pterygoidea externa ) is an inconstant branch, which often arises from the middle meningeal or from a pterygoid artery ; it gives bmnches to the pterygoidei muscles, to the muscles of the soft palate, and to the dura mater, near the sella turcica, and sometimes penetrates into the skull through the foramen ovale.

d. The middle , or great meningeal , or spheno-spinal artery (./?. méningée i media , s. magna , s. spmosa),(l) is the largest branch of the internal maxillary artery.

It arises from the upper part of the origin of the internal maxillary artery. It goes directly upward and gives off branches to the pterygoid ei muscles, to the upper constrictor of the pharynx, to the temporal muscle, and to the muscles of the soft palate ; these are sometimes, although rarely, deficient. When they do not exist they are replaced by the small meningeal artery.

The artery then, either simple or divided, enters through the sphenooccipital hole of the sphenoid bone, into the skull, and then gives off some ramifications posteriorly, which glide into the fissure of Fallopius, penetrate into the cavity of the tympanum and the canal of the facial nerve, are distributed to the membrane of the tympanum, to these nerves, and to the muscles of the tympanum, and anastomose with the stylomastoid artery. Others, which are anterior, sometimes penetrate into the orbit, through the malar bone or the large wing of the sphenoid bone, and to the lachrymal gland. But this trunk, covered on the outer face of the dura mater, above which it projects, and of which it is the largest artery, expands principally in- the anterior and central part of this membrane. It arises, near the anterior edge of the parietal bone, at the median line of the skull, and gives off, forward and backward, numerous branches, which anastomose with the other branches of the middle, and also with those of the anterior and posterior meningœal arteries.

Besides, these branches communicate also with those of the temporal and occipital arteries.

As they project above the dura mater, and follow the grooves of the skull-bones, these indicate their course very well.

e. The inferior maxillary or inferior denial artery (A. maxillaris , s. alveolaris , s. dentalis inferior ), which sometimes arises from the middle meningceal artery, and always comes from the lower point of the origin of the internal maxillary artery, descends between the two pterygoidei muscles, to which it gives twigs, and also sometimes to the temporal muscle : penetrates into the dental canal, through which it passes forward, gives ramifications to all the teeth and to all the lower dental nerves, which occupy the same canals as they do, then emerges from the mental foramen, and anastomoses above with the inferior coronary or labial, and below with the submental artery, and produced, like the preceding, by the facial artery.

(1) Some anatomists, as Sabatier, Boyer, and Bichat, state that it is the first branch of the internal maxillary artery. We have always seen it preceded by one or more of those we have mentioned, and we have never found it, as Mayer states, arising directly from the bifurcation of the external carotid artery. According to our observations, it does not normally arise before the inferior dentar artery, as SÅ“mmering, Murray, and Munroc assert. We have seen that Portal was correct in saying that it is given off as frequently after it. or at least opposite to it.

This emerging branch most commonly arises at some distance from the mental foramen, within the dental canal, and on a level with the small malar teeth, at the place where the inferior maxillary artery bifurcates to produce it and the continuation of the trunk.

f g. Two or more cleep-seated temporal branches {ll. temporalis profundi ) arise from the upper part of the maxillary, and are distributed to the buccinator and the pterygoidei muscles, and especially to the temporal muscle ; penetrate also into the orbit, where they send branches into the lachrymal gland and the eyelids, and anastomose extensively with the ophthalmic artery.

h. The masseter artery ( R . massetericus) is not constant, and arises sometimes from the external temporal, or even the external carotid, or finally from one of the deep pterygoid arteries. It passes over the semicircular notch of the lower jaw into the upper part of the masseter muscle. It gives branches also to the temporal muscle, and to the two pterygoidei muscles, especially to the external.

i. The buccal artery {Ji. buccalis, s. buccinatoria ) is a very constant branch, although it often arises from the deep temporal artery, or from one of the following branches. It comes from the lower part of the inferior maxillary artery, goes downward and forward, along the outer face of the body of the upper jaw, distributes its branches in the buccinator muscles, the muscles of the upper lip, the lower part of the orbicularis palpebrarum muscle, the buccal membrane, sometimes also the anterior teeth to which it comes by several openings which exist in the upper part of the superior maxillary bone, and anastomoses with the branches of the facial, and also with those of the infra-orbital, artery.

k. The superior maxillary or alveolar artery {A. maxillaris superior, s. alveolaris) arises sometimes from one of the deep temporal or from the infra-orbital arterju It is larger than the preceding, goes a little downward and forward, turns on the upper maxillary bone, and sends off numerous large and small branches, one of which is termed the superior dental artery {E. dentalis superior ) into the teeth of the upper jaw. These branches nourish the dental capsules, the periosteum, the germ, the buccinator muscle, the zygonraticus major muscle, and anastomose with the branches of the facial and infra-orbital arteries.

l. The infra-orbital artery {A. infra-orbitalis) is generally smaller than the preceding, and arises near the bottom of the orbit. It soon engages itself in the infra-orbital foramen, and the infra-orbital canal, sends some branches into the orbit and the maxillary sinus, emerges by the infra-orbital foramen, behind the levator labii superioris, thus comes on the front of the face, and terminates in a great many ramuscules, some of which go to the muscles of the upper lip, while the others anastomose with the upper dental artery, the dorsal artery of the nose, the orbitar and the palatine artery.

Finally, at the upper end of the zygomatic fossa, the internal maxillary artery divides into an ascending and a descending branch, which goes inward.

m. The superior palatine artery ( A.palatina suprema , s. descendens, s. pterygo-palatina ) gives off, first, the superior or descending pharyngeal artery (A. pharyngœa suprema , s. descendens). This passes through the pterygo-palatine foramen, and expands in the pterygoid process of the bone, and the Eustachian tube and the upper part of the pharynx. Sometimes it arises from the internal maxillary artery by a distinct trunk. The superior palatine artery descends in the pterygoid canal and divides into several minuscules, which pass through different openings, to go to the soft parts of the palate. The trunk passes through the posterior palatine canal, comes on the palatine arch, rests directly on its lower face, describes a right angle to go forward, forming numerous curves, in its course gives off twigs to the mucous membrane of the palate and to the muciparous glands, and anastomoses forward with that of the opposite side, and sends its latter branches through the anterior palatine foramen into the nasal cavity, where they extend to the lower turbinated bone, communicating with the branches of the artery of the septum and of that of the dorsum of the nose which arise from the facial artery.

n. The last branch, the posterior nasal or sphenopalatine artery (A. nasalis posterior, s. splieno-palatina ), enters through the sphenopalatine hole into the posterior part of the nasal fossa, and divides into two branches, an external and an internal, and sometimes into three.

The internal branch, the posterior artery of the septum of the nose ( A . septi narimn posterior ), descends along the posterior pare of the septum of the nose, sends minuscules to the upper part of the pharynx, and penetrates into the posterior cellules of the ethmoid bone, and also into the upper turbinated bone.

The external branch descends along the outer edge of the posterior opening of the nasal fossae, and usually divides into two ramuscules, which go, the upper to the middle, and the lower to the lower turbinated bone. These ramuscules are distributed principally in the posterior part of the nasal fossa and of the maxillary sinus.

II. INTERNAL CAROTID ARTERY.

§ 1360. The internal carotid or anterior cerebral artery (A. carotis interna , s. cerebralis, s. cerebralis anterior , s. encephalica ) is usually smaller than the external, ascends behind it, before the internal jugular vein, on the outside of the pneu mo-gastric nerve, directly before the vertebral column, to the lower orifice of the carotid canal. It does not generally bend much, although it is sometimes very tortuous, and it is rarely straight.

It seldom gives off branches in this course. It rarely in fact furnishes one of the internal or posterior branches of the external carotid or of the occipital artery. The latter comes from them less frequently than the others. Upward it gives off sometimes a small branch, which goes to the palatine region and to the velum palati.

Immediately below its entrance into the carotid canal it is generally almost horizontal, or at least goes obliquely upward and forward. At the lower part of this canal it goes vertically upward. It afterwards goes forward at nearly a right angle, and becomes almost horizontal, although it ascends a little. After leaving the canal it resumes its primitive direction upward, but proeeeds at the same time forward and inward, and thus comes on the side of the sella turcica. At the posterior part of this excavation it curves a second time at a right angle, goes horizontally in the lateral carotid groove, going outward and a little downward. In this part of its course it accompanies the cavernous sinus of the dura mater, both being inclosed in the same portion of the dura mater, but separated by its proper membrane from the blood which it contains. At the anterior extremity of the lateral face of the sella turcica, below the anterior clinoid process, it describes a thud right angle, and goes upward, backward, and inward. In its course it gives off very trifling branches to the internal ear, to the dura mater, and to the third, fourth, fifth, and sixth pairs of nerves. Opposite the internal extremity of the upper orbitar fissure it divides into two branches, the continuation of the trunk which goes to the brain, and the ophthalmic artery.

Thus it changes its direction five times at least, and this arrangement retards the course of the blood much more, inasmuch as all the curves are sudden and do not occur on the same plane.

The internal carotid artery is intimately united by a very short cellular tissue to the canal through which it passes and which it almost entirely fills.

I. OPHTHALMIC ARTERY.

§ 1361. The ophthalmic artery (JL, ophthalmica ) is a very considerable branch, which exceeds in volume all those hitherto mentioned. It is always single. It leaves the skull through the optic foramen, usually on the outer and lower side, rarely at the upper part of the optic nerve, penetrates into the orbit, sends numerous branches to all parts of the eye, and also larger or smaller branches into the nasal fossæ and the face.

Having come into the cavity of the orbit, it soon ascends on the optic nerve, goes upward and inward, passes between this nerve and the rectus superior muscle of the eye, and thus arrives at the inner part of the orbit and goes forward to the internal angle of the eye.

Its branches vary surprisingly in respect to their origins, their number, and their volume. The principal are :

1st. Usually but not always an external posterior ciliary artery {A. ciliaris posterior), which arises from the outer side of the ophthalmic artery, goes forward along the optic nerve on its outer and lower side, and penetrates the sclerotica directly before the anterior extremity of this nerve.

2d. The lacrymal artery (A. lacrymalis) arises from the upper part of the ophthalmic artery, generally far backward and sometimes very far forward. It rarely arises from the middle meningeal artery, in which case it enters into the orbit, through the upper orbicular fissure, or through a special opening either in the malar bone or in the large wing of the sphenoid bone. It proceeds outwardly under the rectus superior muscle, to which it gives branches, and also to the rectus externus and to the levator palpebrarum muscles. It sometimes sends several through the malar bone into the temporal muscle, where they anastomose with those of the deep temporal artery. In some subjects one or several ciliary arteries arise from it. It then passes across, above or below the lacrymal gland, leaves the orbit at the external angle of the eye, anastomoses with the palpebral artery given off by the ophthalmic artery to form the palpebral arch, and terminates in the orbicularis palpebrarum muscle, the skin of the eyelids, and the tunica conjunctiva.

3d. The posterior upper ciliary artery (A. ciliaris posterior, superior ) is distributed in the same manner as the external, but gives off no branch after passing through the tunica sclerotica. Sometimes all the posterior ciliary arteries arise after the posterior ethmoidal artery ; but they always proceed very tortuously on the surface of the optic nerve, and after dividing into numerous branches, pass through the posterior part of the sclerotica to enter the eye, where they are distibuted in the manner stated in describing that organ.

4th. Next, a small inconstant branch arises and goes to the posterior part of the rectus superior muscle.

5th. The posterior or middle ethmoidal artery (A. ethmoidalis posterior , s. media) is also inconstant, and often arises from the lacrymal artery, from the anterior ethmoidal, or from the supra-orbitar artery.(l)

It gives first branches to the origin of the obliquus superior, rectus internus and externus muscles, then goes inward over the obliquus superior muscle, passes through the ethmoidal . or posterior internal orbital - foramen, comes into the nasal fossæ, and is distributed to the posterior ethmoidal cellules, the sphenoidal sinus, and the antrum Highmorianum ; it anastomoses with the branches of the posterior nasal or spheno-palatine artery and with the anterior ethmoidal artery, then reenters the skull through a small canal in the ethmoid bone, gives ramuscules to the periosteum which covers the anterior and central fossa of the base of the skull, and terminates by again passing into the nasal fossæ through the openings in the cribriform plate.

6th. The central artery of the retina (A. centralis retinae ), arises farther back, directly from the ophthalmic artery, or from the preceding, or from the lacrymal urtery, or from one of the two muscular branches ; it goes into the optic nerve, proceeds forward along ils axis, and distributes itself to the retina, as we shall meniion in describing the eye.

(1) But it is not always the smallest, as Bichat asserts ; we have remarked several times that it was one of the largest branches and much larger than the anterior.

7th. The inferior muscular artery (A. muscularis inferior ), is a considerable and rather constant branch, which sometimes gives off the central artery of the retina and one or more of the ciliary arteries, goes inward, sends branches to the rectus interims and inferior muscles of the eye, and penetrates even into the nasal fossæ.

8th. The superior muscular or supra-orbitar artery {A, muscularis superior , s. supra-orbitaria) is less constant than the preceding, but it comes from the lachrymal less frequently than from the ophthalmic artery. It proceeds forward directly below the orbitar plate, leaves the orbit through the supra-orbitar foramen, gives off branches to the frontal bone, to its periosteum, to the supraciliaris and orbicularis palpebrarum muscles, and to the skin of the forehead, and anastomoses with the other branches of the ophthalmic and with the temporal artery.

The anterior ciliary arteries (A. ciliares anticÅ“ ) arise from this branch and from the preceding ; they divide into fewer branches than the posterior, and enter the sclerotica much farther forward than the latter, near the transparent cornea.

The branches we have described generally arise near the floor of the orbit, not far from each other ; hence why they are generally long. After giving them off, the ophthalmic artery is usually smaller and proceeds along the- internal wall of the orbit, describing numerous curves. Towards the anterior opening of the orbitar cavity it gives off,

9th. The anterior ethmoidal artery (A. elhmoidalis anterior), which goes directly inward, passing over the obiiquus superior muscle, and penetrates through the ethmoidal or anterior internal orbitar foramen into the nasal cavity, where it is distributed to the anterior ethmoidal cells and the frontal sinuses, and anastomoses with the other nasal arteries. It also sends off branches to the anterior region of the dura mater.

The ophthalmic artery now proceeds a short distance within the orbit, afterwards leaves this cavity at the inner angle of the eye, and terminates in giving origin to,

10th. The paljiebral arteries (A. palpébrales]. These arise sometimes by a common trunk ( palpebralis communis) and sometimes separately, the superior a little before the inferior, and go outwardly. They are distributed partly to the conjunctiva, partly and particularly to the eyelids, in which they disappear between the skin and the orbicularis muscle. They divide there principally into two branches, one of which proceeds near the edge ( ramus marginalis) , while the other goes obliquely outward along the base of the eyelid.

The superior palpebral artery anastomoses in this place with the lachrymal, the superciliary branch of the frontal, and even some branches of the anterior temporal artery. It also forms a single or double superior palpebral arch ( arcus tarseus superior), which communicate with each other by numerous ramuscules, and thus form a network.

The inferior palpebral arch ( arcus larseus inferior) is produced in the same manner, by the anastomosis of the inferior palpebral with the infra-orbitar, the lachrymal and the nasal arteries.

All the parts of the eyelids are abundantly provided with vessels by these arterial branches.

11th. The frontal artery (A. frontalis ), which also ascends soon after arising, usually divides immediately into three branches, the supraciliary artery ( A, supraciliaris ), the superficial or subcutaneous frontal artery (A. frontalis subcutanea), and the deep frontal artery (A. frontalis profunda) . By this division it is distributed, 1st, to the upper part of the orbicularis palpebrarum and corrugator supercilii muscles ; 2d, to the frontalis muscle and to the skin of the forehead ; 3d, to the frontal sinus. It extends to the coronal suture and to the temporal region, where it anastomoses with the branches of the external temporal artery; it also communicates in other parts with those of the supra-orbitar and lachrymal arteries.

12th. The nasal artery {A. nasalis) varies much in volume. Sometimes it is a very small branch, terminating at the root of the nose ; sometimes it forms the continuation of the trunk of the ophthalmic artery, descends very low, contributes with the lateral nasal branch of the facial artery to produce the dorsal artery of the nose, extends to the end of the nose, proceeding on the side of this organ, always anastomoses with the inferior palpebral and the facial artery, and gives ramuscules to the integuments and to the nasal bones, to the frontalis muscle, to the internal part of the orbicularis palpebrarum, to the muscles of the nose, and even to the pituitary membrane.

II. CEREDRAL ARTERIES.

§ 1362. After giving off the ophthalmic artery, the internal carotid artery is distributed entirely to the cerebrum, particularly to its anterior portion, the posterior being supplied with blood from the vertebral artery. It properly deserves then to be called, from this point, the anterior cerebral artery (A. cerebralis anterior).

<§ 1363. It gives off, first, small ramuscules, which go inward, and are designed for the posterior part of the optic nerve, for the infundibulum, for the pituitary gland, and for the third ventricle.

§ 1364. It then gives off four branches ; these are the communicating artery, the choroid artery, the anterior cerebral artery, and the artery of the corpus callosum. The first two generally arise directly after each other ; and the carotid artery bifurcates farther on to give rise to the last two. Sometimes, but more rarely, three or all of these branches arise from the same point.

§ 1365. The first, or the posterior communicating artery (A. communicans posterior), goes backward and inward. It approaches that of the opposite side, opens into the posterior cerebral, which comes from the vertebral, artery, or if we prefer it anastomoses with a branch analogous to it, which it meets.

This anastomosis gives rise to the posterior part of the circle oj Willis ( circulus Willissii).

The size of this communicating artery varies extremely. It is generally considerable, and only about one half smaller than one of the succeeding branches, into which the internal carotid artery divides. It is sometimes however very small ; in this case the anastomosis between the internal carotid and the vertebral artery, frequently but not always takes place by means of another and larger branch of the anterior cerebral artery, which opens more outward into the posterior. The communicating artery is sometimes larger on one side than on the other.

Sometimes this artery is a branch of the anterior cerebral.(l) It arises more rarely not from this but directly from the basilar artery, when the posterior cerebral artery does not come from it. and it is given off by the internal carotid.

But the anastomosis almost always exists ; and it is constantly simple or at most double, on each side, when it occurs by considerable branches, although we find others which are accessory and smaller in the cerebral peduncles.

We consider its total absence as one of the rarest anomalies. We have never yet seen it, and Barclay alone mentions one case where the injection penetrated neither from the carotid into the vertebral artery, nor from the vertebral into the carotid.(2)

Several vessels arise from the communicating artery and go to the pia-mater or to the floor of the third ventricle, to the mamillary eminences, to the posterior part of the optic nerves, to the thalami optici, to the cerebral peduncles, to the inner face of the anterior part of the large cerebral lobe, and to the choroid plexuses.

§ 1366. b. Above the communicating artery, the internal carotid always gives off a special branch, the choroid artery (A. ckoroidta) which also arises from its posterior part. (3) This artery goes a little backward and outward, along the posterior edge of the origin of the optic nerve, ascends above the upper part of the cerebral peduncle, and expands partly in the pia-mater of the anterior part of the posterior cerebral lobe anil of the thalami optici, and partly also penetrates through the anterior opening of the lateral ventricle, into this cavity, where its ramifications expand in the choroid plexus.

(1) This anomaly, however, is proportionally very rare. Portal then estimates incorrectly, the relation between the rule and the exception, in saying' that the internal carotid artery usually divides into two branches, the smaller of which is the artery of the corpus callosum, the larger the anterior lobate artery; the latter givingoffthe communicating artery, which sometimes arises directly from the internal carotid. Hilderbrandt seems to think that the two cases are equally frequent, which is just as false.

(2) hoc. cit., p. 47.

(3) We have always found this branch very constant, although several anatomists particularly Mayer, Murray, Portal, Hilderbrandt, and SÅ“mmerring, do not mention it. Haller states (le. anat., vol. vii. p. 5) that it sometimes exists. Sabatier, Boyer, and Bichat assert that is constant , which agrees with our remark. But Bichat errs in saying thatthe choroid is always smaller than the communicating artery. This case frequently occurs, since, as we have observed, the communicating artery is usually large ; but we have often found, when this was small, that the choroid artery was as large or even larger than it.

§ 1367. The internal carotid now divides, at a very obtuse angle and at the anterior extremity of the fissure of Sylvius, into two unequal branches ; these are the artery of the corpus callosum and the anterior cerebral artery.

§ 136S. The artery of the corpus callosum ( A . callosa, s. corporis callosi, s. anterior cerebrica , s. anterior hemisphÅ“ri, s. mesolobica ) is always smaller than the posterior branch. It goes forward and inward, directly before the union of the optic nerves, proceeds to meet that of the opposite side, towards which it converges very much, and after giving off superiorly generally several ramuscules for the posterior extremity of the anterior lobe, for the olfactory and for the optic nerves, it anastomoses with it between the posterior extremities of the first two lobes by the anterior communicating artery (A. anterior communicans , s. anostomotica). This branch is generally very short ; sometimes however, it is three or four lines long ; it is generally much larger in the former case and often very narrow in the second. Its direction is always transverse. Sometimes it is entirely double; and we not unfreqüently find it, double in one half its extent.(l) It gives off, particularly when longer than usual, ramuscules, which go upward and backward, into the septum lucidum, the fornix, and the corpus callosum.

The trunk also generally sends off one or more small branches which proceed forward and outward to the inner part of the inferior face of the anterior lobe of the cerebrum. After this, it is situated directly near that of the opposite side, turns on the anterior extremity of the corpus callosum, ascends to the inner face of the cerebral hemispheres, and divides into several branches, the anterior of which enter into the circumvolutions of this internal face, while the posterior proceed on the corpus callosum, as far as its posterior extremity, where they begin to change their direction and to go upward. All these branches extend to the upper face of the cerebrum and anastomose with those of the succeeding artery, and with those of the posterior cerebral artery, given off by the vertebral artery.

Besides these large branches, into which the artery of the corpus callosum divides above, it also gives off, from its lower and concave part, numerous smaller branches, whtch distribute themselves in the corpus callosum.

Rarely, a large posterior branch is detached on both sides at the place where the two arteries of the corpus callosum meet, and the anterior anastomosing branch becomes the single trunk of the anterior part of the artery of the corpus callosum, which shortly divides into two large branches, a right and a left, or the two arteries arise from a common trunk, and do not give oft a branch posteriorly. This arrangement is remarkable because of the analogy it establishes with the union of the two vertebral arteries into one, the basilar, which is situated on the median line.

(1) Bichat is incorrect in stating that this arrangement is very rare.

§ 1369. The anterior or more properly the middle cerebral artery (A. cerebri anterior, s. media , s. hemisphcerica media, s.fossÅ“ Sylvii, s. sylviana), the last and the most posterior branch of the internal carotid, is always much larger than the preceding. Soon after its origin it goes outward, and only a little inward ; it enters the fissure of Sylvius, gives off, at its upper and posterior part, numerous, generally small, ramuscules, some of which penetrate into the anterior extremity of the posterior lobe, others into the posterior extremity of the anterior lobe, and afterward divides generally about half an inch from its origin into two, three, or four large branches. The largest of the latter are turned backward, soon bifurcate, and proceed, closely against each other, into the bottom of the fissure of Sylvius, where they go upward and backward. The anterior attain the posterior and external part of the anterior lobe, and the posterior the anterior central part of the posterior lobe, gliding in the circumvolutions of the posterior face of the first and the anterior face of-the second, but penetrating mostly into their substance, through their outer face, and thus extend to the upper edges of the hemispheres, where they anastomose with the ascending branches of the anterior and posterior cerebral arteries.

§ 1370. The anterior and middle cerebral arteries are not always arranged symmetrically. The two large middle arteries not unfrequently arise (as Haller states and as we have verified) from the right carotid only, and the anterior, which is smaller, from the left carotid, an arrangement which deserves to be remarked as indicating the predominance of the right side over the left.

Sometimes also only the left anterior artery comes from the internal carotid of the same side, and the other three come from the right. We have seen this anomaly in several subjects.

If we add the union of the arteries of the corpus callosum at their origin, which we mentioned above, we here find a remarkable repetition of several of the varieties to which the origins of the trunks coming from the arch of the aorta are subject.

4. Arteries Of The Upper Extremities

§ 1371. The arteries of the upper extremities, for which we cannot find a better term than that of the brachial arteries(l) ( J1 . brachiales), arise on each side by a single trunk, generally called the subclavian arteiy (A. subclavia).

(1) This term is generally applied only to that portion of the artery which corresponds to the arm, and which might more properly be termed the humeral artery.

I. SUBCLAVIAN ARTERY.

§ 1372. The two subclavian arteries {A. subclavia) arise from the ascending aorta, and extend to the scaleni muscles. They differ in their mode of origin ; for the left subclavian artery arises directly from the arch of the aorta, while the right proceeds indirectly from it, as it is the external branch of the trunk of the innominata ( truncus communis innominatas), which bifurcates and gives origin to it and to the right primitive carotid.

This at least is the most common arrangement. Sometimes, but rarely, the subclavian arteries arise directly from the arch of the aorta. We may there find two principal differences. Sometimes in fact the trunk of the innominata gives off the right subclavian and the carotid, the subclavian artery arising on the right, outside of the carotid, which is the least but also the rarest anomaly. Sometimes the right subclavian artery arises more to the left, until it is the extreme left trunk of those which arise from the arch of the aorta, below the left subclavian artery, and goes to the right, towards the corresponding limb, passing behind the other trunks, rarely directly, more frequently between the trachea and the esophagus, and still more frequently between the esophagus and the vertebral column.

§ 1373. The first branches of the subclavian artery are never constant. They often and in fact almost always arise from its upper extremity, directly before its passage between the scaleni muscles. But sometimes the artery gives off much sooner, and even near its origin, considerable branches, which go to the thymus gland, to the upper part of the pericardium, also to the trachea, to the bronchiæ, and to the esophagus (A. thymicÅ“, pericardiacee superior , anterior et posterior , broncliicÅ“, Å“sophagece, broncho-Å“sophagece), but they rarely or never belong to these parts alone, although they distribute branches to all. Even when these branches arise from the subclavian artery (which occurs on the left side more frequently than on the right, because it descends deeper) its course is no shorter, but it gives off no branch until just before passing between the scaleni muscles. Here, however, several large branches arise from it. These may be distinguished generally speaking into the upper or posterior and the lower or anterior branches ; and they vary much, for, 1st, the same twigs do not always arise from the same branches, so that the latter are not always of the same caliber ; 2d, small branches sometimes arise from the subclavian artery, by a common trunk, whence their number varies : 3d, they do not always emerge from the same point of the subclavian artery, the inferior arising sometimes farther forward, and the superior farther backward than usual.

A. UPPER POSTERIOR BRANCHES.

§ 1374. The most constant of the upper and posterior branches are two, the vertebral artery and the inferior thyroid artery.

I, VERTEBRAL ARTERY.

§ 1375. The vertebral artery (v3. vertebralis ) is generally the first and largest of the two upper branches of the subclavian artery. Shortly after arising, it enters the arterial canal of the cervical vertebrae, and goes from below upward. This artery shows a great disposition to change its origin, and to arise directly from the arch of the aorta. We shall remark, 1st, that this anomaly, however common it may be, is seldom seen on the right side (at least to our knowledge), and that it rests always on the left ;( 1 ) 2d, that when it occurs, the vertebral artery is almost always inserted between the left carotid and the left subclavian arteries. If this branch arises directly from the arch of the aorta more frequently than the others, it may be attributed, we think, to the following facts : 1st, in the normal state it is the first branch of of the subclavian artery ; 2d, the vertebral vein normally empties itself into the common trunk of the subclavian and jugular veins. The other fact, that the anomaly appears almost entirely on the left side, seems to us to depend on this, that the division of the trunk into branches characterizes the left side of the ascending aorta even in the normal state, since the subclavian arteries there arise separately, and are not blended in a single trunk, as on the right side. The greater length of the left trunk of the innominata vein may contribute to it, since this anomaly should be considered, as we have remarked, an imitation of the arrangement of the venous system. Finally, the situation of this artery between the left carotid and the left subclavian arteries probably depends on its arising, in the normal state, from the internal and posterior side of the subclavian artery.

We sometimes but rarely find on the right side a similar anomaly where the vertebral artery arises from the bifurcation of the trunk of the innominata ; this is still more curious, because in comparing this arrangement with that on the left side we have a new proof that the anomaly does not destroy in the two sides the character of the normal type.

We know of only one case where the right vertebral artery arose from the arch of the aorta ; but that of the left side also presented the same anomaly.

(1) This might be easily proved by numerous quotations. Of all the authors who mention this variety Mayer is the only one who asserts the contrary; for, without speaking of the left vertebral artery, he asserts only that the right sometimes arises directly from the arch of the aorta. This assertion is so cont radictory to observation that it can be explained only by considering it as a typographical error.

A second anomaly of the vertebral artery consists in its division into several trunks. Sometimes then one of the trunks arises directly from the arch of the aorta ; the other, which is generally smaller, from its usual place ;(1) or both come from the subclavian artery, at. a greater or less distance from each other. Perhaps the first arrangement also is found only on the left side ; at least in a specimen before us, and where the anomaly exists on the right, the two vertebral arteries are branches of the subclavian artery. In both cases one of the trunks, particularly the largest, enters the vertebral canal higher than usual. Sometimes it unites with the other, which enters at the normal place ; sometimes it unites with it before entering this canal ; sometimes, finally, the smallest branch extends into the veitebral canal after passing over one or more vertebral foramina.

Even when the vertebral artery is normal in respect to its origin, it enters the vertebral canal at several different points. Its proper place is the vertebral foramen of the sixth cervical vertebra. (2) In extremely rare cases this artery enters through the vertebral foramen of the seventh cervical vertebra.(3) Even when it arises lower than usual, from the arch of the aorta it however enters into the hole of the sixth cervical vertebra, and we have frequently seen it in this case not enter the vertebral canal until it reaches the fifth vertebra.

More frequently, although not very often, the vertebral artery, even if not double, enters through the vertebral foramen of the fifth, fourth, third, or even the second cervical vertebra. We know of no case in which it has been found entirely out of the vertebral canal, and we have never known it to leave this channel lower than the upper vertebra, or to leave a vertebra, pass through a certain extent on the anterior face of the transverse processes, and enter again into the vertebral canal.

Finally, the vertebral artery of one side is very frequently much larger than that of the other, although according to our observations the sides of the body have no effect on this disproportion.

This anomaly confirms the general rule that the synonymous arteries which go to the single organs on the median line of the body often differ in volume and enlarge on one side at the expense of the other.

(1) Henkel, Anmerkungen von weidernatürlichen Geburten , zweite Sammlung, p. 10, 11. — Huber, Dc arcus aortce ramis ; in the Act. Helv., vol. viii. p. 68-102.

(2) We have always observed this, except in a very few instances. Haller (/c. anat.fasc. ii., e.vplic. icon. 2, art. thyr. infer., not. c) and Scemmerring (p. 177) are then correct in saying that this arrangement is normal. Mayer mistakes in saying (p. 110) that there is for the vertebral artery a special opening, through which it enters into the vertebral canal, sometimes in the seventh and sometimes only in the sixth cervical vertebra. This opening always exists except in a very few instances in the seventh cervical vertebra ; but the vertebral artery rarely or never passes through it and always enters through the sixth. What Mayer considers the normal state is a rare anomaly, and vice versa. Monro ( Outlines , <f-c., vol. iii, p. 301) is also mistaken in thinking that the artery enters through the seventh cervical vertebra as often as it does through (he sixth.

(3) Bichat (p. 193) is correct in saying that it sometimes but rarely enters through a similar foramen of the seventh cervical vertebra. This arrangement is rare, as Haller, Murray, and Scemmerring have not spoken of it, although they mention the next.

§ 1376. The vertebral artery ascends in an almost straight line to the second cervical vertebra ; but at this point it becomes tortuous and describes several curves, four of which are very remarkable. First, it penetrates into that part of the canal which belongs to the transverse process of the second vertebra, forming a right angle, assuming an entirely horizontal direction, and going transversely outward ; then passing through this opening, it describes another right, acute, or obtuse angle, resumes its first direction, and becomes perpendicular again at the upper cervical vertebra. When it has passed through the vertebral foramen it inclines again at a right angle, resumes a second time a horizontal direction, and goes backward and inward, turning around on the articular process of the first Cervical vertebra, along its posterior groove. From the posterior extremity of the articular process it goes gradually and at an obtuse angle inward and upward, and soon enters the cranium, passing through the dura mater and the large occipital foramen directly above the occipital condyle. Having entered the skull, it is situated first on the side, then on the lower face of the medulla oblongata, and ascends forward and inward on the basilar process of the occipital bone. There the two arteries approach each other, and after passing usually more than an inch within the cavity of the skull, they unite at an acute angle, either a short distance behind the posterior edge of the pons Varolii, or on this edge, or even in its centre. They always, as far as we know, unite and give origin to a single trunk, the basilar artery (A. basilaris ), which is much smaller than the two branches which produce it. In size it nearly equals the internal carotid artery after it gives off the ophthalmic artery. It proceeds forward to the centre of the lower face of the pons Varolii, and divides a£ its anterior extremity into two large branches, a right and a left.

§ 1377. In this course the vertebral artery generally gives off no branches, or at least but small and inconstant ones. These- branches are' distributed to the anterior deep muscles of the neck. In this respect the vertebral artery resembles the internal carotid.

§ 1378. From the portion within the vertebral canal several small branches pass forward, outward, and backward, generally between every two vertebrae, and go to the vertebrae, to the intertransversarii, to the multifid us spinæ, to the anterior deep muscles of the neck, and to the small muscles of the head.

Internal branches, which are also very small, pass through the intervertebral foramina, either alone or attended with small arterial twigs from the other branches of the subclavian artery, penetrate the vertebral canal and are distributed partly to the nerves, others to the anterior and posterior sides of the dura mater and to the pia mater of the spinal marrow. They anastomose with those of the opposite side and with the anterior and posterior spinal arteries.

Considerable branches arise- from that part of the vertebral artdry between the first and the second cervical vertebrae, and also between the latter and the occipital bone. Some go outward, are expanded in the transversales colli and the coinplexus minor muscles, and anastomose with the branches of the ascending cervical artery, and sometimes entirely replace it. The others proceed backward and outward and are distributed in the posterior and lateral small muscles of the head. Some go inward and anastomose with the synonymous branches of the other side. Finally, man}' enter the tissue of the dura mater.

§ 1379. The largest branches arise from that part of the vertebral artery within the skull. From the difference of caliber between the branches which it sends out of the cavity of the skull, this part is frequently much larger on one side than on the other, although both have primarily the same diameter at their origin and although the side of the body has no necessary influence upon this difference.

The branches which arise before the two vertebral arteries unite are the anterior spinal artery, the posterior spinal artery, and the inferior artery of the cerebellum.

§ 1380. The posterior spinal artery (A. spinalis posterior) is the smallest, and often comes from the inferior artery of the cerebellum. It arises the lowest and from the outside of the vertebral artery, goes inward on the posterior face of the spinal marrow, and descends on each side along the posterior spinal groove to the end of the spinal marrow. The two arteries are very tortuous and are parallel to each other. They are always enlarged by the accessory ramuscles of the vertebral, the deep cervical, and the intercostal arteries which pass through the intervertebral foramina, and anastomose by numerous transverse branches, which generally correspond to the intervertebral spaces ; so that each portion of the spinal marrow between two vertebrae has its special vascular circle, even as the four cerebral arteries form one by their anastomoses. •

§ 1381. The inferior artery of the cerebellum (,R. inferior cerebelli) a-lso arises from the outer side of the vertebral artery and is usually double on both sides.

One, the posterior inferior artery of the cerebellum, arises farther backward, and goes backward, upward, and inward, proceeds on the lateral parts of the medulla oblongata, distributes its branches to the tela choroidea of the cerebellum and to the floor of the fourth ventricle, and ascends between its two hemispheres to its vermiform eminence and to the inner face of its two hemispheres. This branch often exists on one side only, and then it is observed particularly when the inferior artery of the cerebellum arises very far forward.

The anterior inferior artery of the cerebellum sometimes arises at the origin, sometimes also at the extremity of that portion of the vertebral artery within the skull. In some subjects, particularly when the vertebral arteries unite early, it comes from the basilar artery. These varieties are observed even on both sides of the body at once. The anterior inferior artery of the cerebellum not only frequently exists alone but it is generally much larger than the posterior. It is sometimes much smaller on one side than on the other. It proceeds very tortuously outward and backward to the lower face of the cerebellum., where impasses on the grooves which it crosses and divides into branches, some of which go backward and others forward. These branches also cross the direction of the grooves of the cerebellum ; the small ramifications alone become parallel and finally penetrate into them.

§ 1382. The anterior spinal artery (A. spinalis anterior) generally commences a short distance from the lower edge of the pons Varolii, even when the two vertebral arteries unite much higher than usual. It arises from the internal part of the trunk and soon unites with that of the opposite side in a single trunk on the median line, which descends along the anterior groove of the spinal marrow. Generally, particularly when the two vertebral arteries unite higher than usual, we find a small anterior and superior spinal artery, which is sometimes single and arises from the top of the angle of union, and sometimes double, which blends likewise with that of the opposite side, and which, proceeding also from above downward, soon anastomoses with the lower. The single trunk of the latter, which corresponds to the median line, is often divided in its course and thus forms considerable islands. Its upper part receives also from all or most of the intervertebral foramina considerable branches, which are given off by the vertebral or the other cervical arteries to the anterior face of the spinal marrow and anastomose with it. During its course, which is very tortuous, it sends off on each side numerous branches to the spinal marrow.

II. BASILAR ARTERY.

§ 1383. The basilar artery (A. basilaris, s. meso-ccp'halica) is comstant, and arises, proceeds, and varies in the manner mentioned above. We however sometimes remark in its arrangement a tendency to a want of union or to the separation of the vertebral arteries, since it forms islands, especially at its posterior part. This artery is however the only one in which we have observed this arrangement. It very soon divides into two parts, which almost immediately unite. We consider this anomaly as very rare, not only because we have never seen it but twice, but because it is not mentioned by the most correct angeiologists.(l) It is curious not only as an anomaly, but because it increases the analogy between the basilar and the anterior spinal arteries, which are already so similar. It is not unimportant to say, that in the two subjects which presented this unusual arrangement the anterior communicating artery of the two internal carotids presented analogous divisions. In the latter however this anomaly is much more common than in the'basilar artery.

(1) An arrangement has been figured by Heuermann ( Physiologic , vol. ii. tab. 8) where the two vertebral arteries were connected behind their union by a large trans'verse branch, to give rise to the basilar artery, which seems to have some relation with this anomaly ; but more probably it consisted only in the union of the anteriorspinal arteries, since the two 'vertebral arteries are not v-ct united behind this branch.

From both sides of the basilar artery numerous branches arise, generally at right but sometimes at angles slightly acute, backward, which vary much in number and volume and do not correspond perfectly on both sides. The smallest enter into the pons Varolii and the nerves which come from it ; the largest, even when the usual inferior arteries of the cerebellum do not exist, proceed even to the lower face of the cerebellum.

Some branches, the internal auditory arteries (A. auditives internez ), enter into the internal auditory foramen, expand in the labyrinth, and anastomose with the branches of the internal and of the external carotid arteries which enter into this organ.

§ 1384. At its anterior extremity, in the middle of the anterior edge of the pons Varolii, the basilar artery usually divides into four branches, two on each side, the superior artery of the cerebellum and the posterior cerebral artery.

§ 1385. The superior artery of the cerebellum (A. cerebelli superior) which is almost as large as the inferior, is rarely deficient on one side, in which case it is replaced by a branch of the following. It is more frequently double ; and then the vertebral artery divides into five branches, of which the two superior arteries of the cerebellum are situated very near each other : sometimes but much more rarely, it arises some lines behind the anterior extremity of the vertebral artery. It goes transversely outward and upward, directly behind the anterior edge of the pons Varolii, then proceeds a little backward, turns upon the pons Varolii to arrive at the anterior edge of the cerebellum., and divides into superficial and deep branches. The first proceed backward on the ridge of the cerebellum to its posterior edge, where they anastomose with the branches of the inferior artery of the cerebellum ; the others penetrate upward into the anterior lobes.

§ 1386. The two anterior branches, the posterior or deep cerebral arteries, Lobaires postérieures du cerveau , Ch. {A. cerebri posteriores , s. profundœ), are much larger than the superior arteries of the cerebellum. They arrive at an acute angle, separate much from each other, and go forward and outward. They usually give off near their origin and at their upper and external part several branches, some of which are considerable and go to the cerebral peduncles, to the thalami optici, to the tubercula quadrigemina, and to the valve of Vieussens. After proceeding a short distance they divide into two branches, the communicating artery and the continuation of the trunk.

The communicating artery is situated inward, and is smaller than the other. Its direction is outward and forward and it proceeds to meet the anastomosing branch of the internal carotid artery, with which it unites.

The continuation of the trunk of the posterior cerebral artery, which is usually the smallest of the three proper cérébral arteries, sometimes aiises from the internal carotid artery, previous to its bifurcation, and sometimes also from the union of the anastomosing branches given off by the internal carotid and the vertebral arteries. It goes outward and upward, before the third pair of the cerebral nerves, and turns on the cerebral peduncle, to the lower face of which it gives some ramuscules, which thus arrive at the thalami optici and the tubercula quadrigemina, penetrate into the third ventricle, and are distributed principally to the choroid plexus. Finally, it goes on one side to the posterior part of the cerebrum and of the corpus callosum, and also to the thalami optici on the other, particularly to the lower face of the cerebral hemispheres. It anastomoses very frequently with the anterior or central arteries and with the arteries of the corpus callosum, which arise from the internal carotid artery.

§ 1387. The peculiarities presented by the arteries of the brain have been described before or will be mentioned when we speak of the encephalon.

II. INFERIOR THYROID ARTEEY.

§ 1388. The inferior thyroid artery (Jl. thyroidea inferior, s. sacro thyroidea, Barclay ) arises from the subclavian artery, more outward and forward than the vertebral artery, from which however it is not always the same distance. It most generally gives off the inferior thyroid branch and several twigs, which go to the muscles and to the slan of the neck, the back, and the shoulder.

This artery is large, particularly in the child, where it is equal to the subclavian or even the carotid artery. Its size however varies much, because that one or more branches which it commonly furnishes frequently arise from other trunks, but the arteries which generally come directly from the subclavian artery are rarely given off by it. This is true for instance of the internal mammary artery, and the former is true in regard to the branches which go to the muscles of the neck, shoulder, and back. Sometimes it goes only to the thyroid gland. In other cases it is uncommonly large, because it gives off not only the usual branches but also the internal mammary artery. In rare cases, on the contrary, it does not deserve its name, because it gives branches only to the muscles and the inferior thyroid arises from the common carotid artery, or does not exist as a separate vessel, but is blended with the superior thyroid artery. This anomaly is curious, as it is a repetition of the normal formation of most mammalia.

Another and somewhat similar anomaly is when the inferior thyroid artery is uncommonly small, either on one or both sides, and one or both of the superior thyroid arteries are larger in the same proportion, or finally when beside the two common thyroid arteries, there is also a third (Jl. thyroidea imu , s. Neubaueri), which arises lower down either from the arch of the aorta on the right of the left carotid or from the common trunk of the carotid and the Subclavian artery, when the anomaly occurs on the right side, or from the common trunk of tin carotids of one side only, df finally from both sides at once, sometimes higher and sometimes lower.

We must also mention here the rare anomaly where the inferior thyroid artery is totally deficient on one side, while on the other, in the usual place, particularly on the right, instead of the two inferior thyroid arteries, we have a common trunk, ( 1 ) which arises sometimes from the aorta and sometimes from its usual place. We have twice observed a case resembling this, where the inferior thyroid artery arose from the arch of the aorta, between the trunk of the innominata and the left carotid arteries.

III. SUPERIOR SCAPULAR ARTERY.

§ 1389. In most cases the inferior thyroid artery, immediately after arising, gives off the superior scapular artery (R. transversus scapulÅ“, s. scapularis transversa, s. scapularis superior , s. cervicalis superficialis ), which however sometimes arises from the subclavian artery, sometimes singly, and sometimes by a common trunk with the following. It goes transversely backward and outward behind, and a little above the clavicle between the scalenus anticus and the scalenus médius ; gives branches to the sterno-thyroideus,the sterno-hyoideus, the omohyoideus, the scaleni, the trapezius, and the supraspinatus muscles ; passes between the spine and the glenoid cavity of the scapula, and enters the infraspinalis fossa. There it divides into several branches, the smallest of which usually pass through the semicircular notch to the anterior face of the scapula and to the subscapularis muscle, while the largest are distributed on the posterior face of this bone, to which it gives one or more nutritious twigs, and terminates in the infraspinatus muscle. Another branch arises from this point and goes forward between the proper and common ligaments of the scapula, distributes itself in the articular capsule of the shoulder and to the upper and anterior jtart of the deltoides muscle, and anastomoses by several large branches with the anterior circumflex artery of the arm and with the great thoracic artery.

IV. TRANSVERSE CERVICAL ARTERY.

§ 1390. The transverse cervical artery (Jl. cervicalis superficialis, s. cervicalis transversa, s. colli transversa ), which is generally as large as the preceding, arises from the inferior thyroid artery, a little higher and at some distance from it outwardly ; it often arises directly from the subclavian artery. It goes transversely outward and backward. It is situated at first on the side of and a little behind the superior capsular artery, and it gives off in this course branches to the scaleni muscles and divides into two large branches on a level with the upper edge of the shoulder. The ascending branch becomes the principal branch of the trapezius and also sends some ramuscales to the levator scapulae muscle ; the other descends along the base of the scapula, between the rhomboidei and the serratus magnus muscles, in which course it gives off twigs to these muscles and also to the lower part of the trapezius muscle.

(1) Burns, loc. cit., p. 331.

§ 1391. A little higher, one or more small branches ( R . thoracici ) arise very constantly from the inside of the inferior thyroid artery ; these go upward and inward to the lower part of the longus colli muscle, penetrate also the spinal canal through the intervertebral foramina, but go particularly to the trachea and to the esophagus. The latter are termed the bronchial and the esophagceal arteries (A. branchiales, Å“ sophageÅ“, s. broncho-Å“sophageÅ“) .

§ 1392. After passing through rather a long course upward without giving off any branch, the inferior thyroid artery divides into two branches, the ascending cervical artery, which is generally much smaller and goes upward and outward, and the thyroid artery, which may be considered as the proper continuation of the trunk.

V. ASCENDING CERVICAL ARTETE.

§ 1393. The ascending cervical or the superior dorsal artery (A. cervicalis ascendens, s. dorsalis supremo) is a very constant branch of the inferior thyroid artery and sometimes but rarely arises from the subclavian artery ; this happens particularly when the branches already described arise separately from the proper thyroid artery. Sometimes also it arises from the internal mammary artery. It ascends along the transverse processes of the cervical vertebrae, between the longus colli and the scaleni muscles. In its course it gives off backward, outward, and upward several considerable branches, which are distributed in the upper part of the trapezius, the levator scapulae; the serratus magnus, the se,rratus posticus, the scaleni, and the splenii muscles, and the skin of the neck : the trunk generally goes backward, below the transverse process of the third cervical vertebra, penetrates deeply between the transversalis colli and the complexus minor muscles, and having thus come upon the posterior face of the neck, it terminates in twe principal branches ; the smaller ascends behind the transverse processes of the cervical vertebrae, gives ramuscules to the complexus minor muscle and to the posterior small muscles of the head, anastomoses with the vertebral and occipital arteries, and finally penetrates into the spinal canal between the first and second cervical vertebrae, where it terminates in the dura mater. The other is larger and is the continuation of the trunk : it goes outward between the fasciculi of the complexus major muscle, and terminates in this muscle and in the digastrieus and the posterior muscles of the head .

§ 1394. The thyroid branch (R. thyroideus) sometimes arises singly from the subclavian artery, from the aorta, the innominata, or from the common carotid artery. It is sometimes entirely deficient in some subjects, but is generally the largest branch of the inferior thyroid artery. It is very tortuous and curves very much in ascending toward the thyroid gland. It usually passes behind, sometimes but rarely before, the primitive carotid, in order to arrive at this gland. Before reaching it, it divides into several branches, which enter this organ principally on its lower edge and lower face and anastomose with each other and with those of the superior thyroid artery.

The thyroid branch also gives in its course smaller ramuscules to the longus colli muscle, to the pharynx, and particularly to the larynx. The latter is termed the inferior laryngeal artery (Jl. lanjngea inferior).

VI. LOWEST THYROID ARTERY.

§ 1395. Besides the branch described (§ 1364), another branch called the lowest thyroid artery (Jl. thyroidea ima ) arises, sometimes from the primitive carotid or from the innominata, from the arch of the aorta or from the subclavian artery, by a trunk in common with that of the opposite side.

This anomaly occurs on the right side more frequently than on the left ;( 1 ) we have never observed it on the latter side, although we have frequently seen it on the other. In one case only, where the origin of the inferior thyroid artery was abnormal, it did not arise from the left side of the arch of the aorta, but from the right side, between the innominata and the left carotid artery ; thence it passed before the trachea to go to the left side of the thyroid gland, while the origin and direction of the right was normal. This anomaly then seems properly to belong to the right side, even as the similar anomaly of the vertebral artery appears exclusively on the left side.

Finally, whether this abnormal artery forms a part or the whole of the inferior thyroid artery, whether it arises from the innominata, or from the arch of the aorta, or deeply from the primitive carotid artery, it always passes on the anterior face of the trachea to go to the thyroid gland, into which it enters from below upward. It cannot then escape being wounded in the operation of laryngotomy.

(1) We have found it nine times on the right. Hubert (toe. cit., p. 84) has seen the lowest thyroid artery arise four times from the common trunk, three times on the right and only once on the left side. Neubauer has also seen the right coming from the aorta (in Erdmann, Descrip, art. thyr. imee, Jena, 1772). Ramsay (Account of an unusual conformation of some muscles and vessels, in the Edinb. Med. and Surg\ Journ., vol. viii. p. 281-283, tab. 1, fig. 2) has found it arising from the innominata trunk. Loder has twice seen it arising from the aorta, between the right carotid and the subclavian arteries : the innominata trunk did not exist in these two cases (De nonnullis arteriarum varieUdibus, Jena, 1781).

VII. DEEP CERVICAL ARTERY.

§ 1396. The deep cervical artery (A. cervicalis profunda) often forms a special trunk, which arises from the back side of the subclavian artery, a little more externally than the preceding, but frequently by a common trunk with the superior intercostal artery. It is rarely given off by the inferior thyroid or even by the vertebral artery ; in the latter case its origin is generally a little below that of the vertebral artery. It more rarely comes from the upper part of the latter, in which case it sometimes descends between the first cervical vertebra and the occipital bone, and is afterwards distributed as usual, but so that its lower branches are almost always supplied by the other branches of the subclavian artery.

It goes obliquely upward and outward, passes backward between the transverse processes of the sixth and seventh cervical vertebrae or the latter and the first dorsal vertebra. It ascends between the transversale colli, the spinalis colli, and the semispinalis dorsi muscles on one side, and the digastricus and the complexus muscles on the other. It also distributes branches to the scaleni, the complexus minor, the cervicalis descendens, the trapezius, the splenii, and the small posterior muscles of the head, and anastomoses, especially above, near the occipital foramen, with the branches of the vertebral and occipital arteries. It also sends ramuscules into the spinal canal through the intervertebral foramina, which anastomose there with the spinal arteries given off by the vertebral artery.

B. INFERIOR BRANCHES.

§ 1397. The inferior branches of the subclavian artery are the internal mammary artery and the superior intercostal artery.

I. INTERNAL MAMMARY ARTERY.

§ 1398. The internal mammary artery (A. mammaria interna , s. sternalis , s. substernalis) is much smaller than the vertebral and the inferior thyroid arteries. It arises ordinarily and very constantly by a -distinct trunk from the anterior or inferior side of the subclavian artery, nearly opposite the inferior thyroid artery. It however in some rare cases, one of which is now before us, arises by a common trunk with the latter, or on the right side from the innominata,( 1 ) or even from the arch of the aorta. (2)

It generally goes downward and inward, but sometimes also ascends a little before taking this direction, which it long preserves. It descends almost in a straight line to the posterior face of the anterior wall of the chest, on the costal cartilages between the intercostales and the triangularis sterni muscles, nearer its internal than its external extremity, consequently not far from the two edges of the sternum, which it also approaches a little below.

(1) Neubauer, loc. cit., p. 33.

(2) Bcehmer, De quat. et quinq. aortæ ram.; in Haller, Collect, diss. anat.. vol. ii. p. 452.

Besides several branches which go from its upper part to the lower part of the anterior muscles of the neck, it sometimes gives off a superior bronchial artery, the thymic, and a branch which is distributed to the pericardium and also to the anterior mediastinum. But its upper part constantly gives off a branch which accompanies the diaphragmatic nerve, called the superior diaphragmatic artery (A. diaphragmatica superior , s. pericardio-diaphragmatica). This branch sends ramuscules to the pericardium, to the internal wall of the mediastinum, and to the esophagus, and expands in the anterior and middle portion of the diaphragm, where it anastomoses with the inferior diaphragmatic artery.

In its course along the sternum the internal mammary artery gives off external and internal branches.

The external branches, the anterior intercostal arteries, {A. intercostales anteriores ), are usually larger and more numerous than the internal. Their number is not exactly the same in every part, but they equal in number the intercostal spaces, over which the internal mammary artery passes. They generally proceed along the lower, rarely along the upper edge of the ribs, and almost always in the latter case one intercostal space contains two of them. They go backward between the intercostales interni and extern! muscles, and anastomose with the intercostal arteries given off by the descending aorta and with the thoracic arteries which arise from the axillary artery.

One of these branches, the fifth, sixth, or seventh, has been called the musculo- diaphragmatic artery (A. musculo-phreniea ). It is usually very considerable, sometimes as large as the trunk, of which it seems even to be a continuation. It is distributed not only to the anterior part of the diaphragm but also it arrives at the upper part of the broad abdominal muscles, whence its name, where it anastomoses with the epigastric artery.

The internal branches, which are smaller and fewer than the preceding, go, some to the internal face of the sternum, others to the anterior face of the pericardium, and some, viz. the deepest, to the anterior part of the diaphragm ; finally, others leave the pectoral cavity through the intercostal spaces and are distributed in the upper part of the abdominal muscles.

The trunk of the internal mammary artery commonly divides into two principal branches of different sizes, an external and an internal. This bifurcation occurs sometimes higher and sometimes lower, and occasionally it is seen opposite the anterior extremity of the fifth rib, and sometimes only opposite the eighth.

The external branch goes obliquely outward, along the costal cartilages, above the intercostal spaces. It terminates by the lowest of the anterior intercostal arteries and by small branches which enter the anterior edge of the diaphragm and the upper part of the broad abdominal muscles. It is also called the superior epigastric artery (Æ epigastric a superior).

The internal branch proceeds perpendicularly downward, passes between the anterior and internal digitations of the diaphragm, and comes upon the posterior wall of the rectus abdominis muscle, where it soon divides into several branches, which descend vertically and anastomose as high as the umbilicus with the ascending branches of the epigastric artery and also with the ramifications of the external branch.

II. SUPERIOR INTERCOSTAL ARTERY.

§ 1399. The superior intercostal artery (dZ. intercoslalis suprema , s. prima) arises more externally than the preceding, and is given off from the posterior part of the subclavian artery. It is the smallest and the most external of the four constant branches of the latter, and varies in size. Sometimes it is very small ; in this case it arises almost always directly from the subclavian artery. It is rarely given off by the inferior thyroid artery, and it frequently arises by a common trunk with the deep cervical artery.

The distribution of this artery varies very frequently, especially in regard to its extent. It however always goes downward and outward, passing on the neck, and gives upward and downward branches, of which the lower are much larger than the upper.

The superior branches go to the transversalis colli muscle and send branches to the deep muscles of the back.

The inferior, which are a continuation of the trunk, divide into external and internal or posterior branches.

The external or intercostal branches (R. interossei) proceed along the lower edge of the first and second ribs, between the intercostalés interni and externi muscles. They generally do not extend very far forward and divide into two ramuscules, an upper and a lower, which follow, the former the lower edge of the upper rib and the second the upper edge of the lower rib, and are distributed in the posterior part of the intercostales muscles between which they proceed, and anastomose before with the superior anterior intercostal arteries (§ 1397). Sometimes we find two branches in the same intercostal space, one of which gives off two twigs.

The posterior , internal or dorsal branches ( R . dorsales) usually arise more or less opposite the external and divide like them into two ramuscules, the internal of which is almost always larger than the other, and enters into the spinal canal through the intervertebral foramen, is distributed to the spinal membranes and the spinal marrow, and anastomoses with the spinal arteries which arise from the vertebral artery ; while the external, proceeding between the ribs goes backward, where it enters the deep muscles of the back, the multifidus spinse and the spinalis dorsi.

When the superior intercostal artery is very small, it is distributed only to the first intercostal space, but its branches generally extend to the second.

It more rarely gives origin, as we have already said, to the deep cervical artery, and it also gives off very near its origin an esophageal or bronchial artery (A. œsopliagea et bronchialis), which varies in size and turns inward and forward, sending branches to the lower part of the trachea, also to the centre of the esophagus, and likewise gives them to the bodies of the upper dorsal vertebrae, and communicates by broad anastomosing branches with the other esophageal and bronchial arteries.

§ 1400. The subclavian artery gives off those branches only which we have described. Sometimes however it sends from its lower and anterior side a considerable branch to the lymphatic glands in the upper region of the chest. It also gives off above the lower extremity of the scalenus anticus others, which go outward to some of the axillary glands.

§ 1401. The artery of the upper extremity then assumes a transverse direction, separates from the trunk, goes downward and outward between the scalenus médius and anticus, and is called the axillary artery.

II. AXILLARY ARTERY.

§ 1402. The axillary artery {A. axillaris) extends from the scaleni muscles to the lower extremity of the axilla. It is situated between the chest and the arm, its upper part being nearer the former, while its lower part approaches the latter because it proceeds obliquely downward and outward. For a short space its upper part is covered only by the skin and the platysma myoides muscle ; below we find the clavicle before it, as it passes behind its centre the subclavius muscle, and still lower the outer part of the pectorales muscles. Backward and outward we observe, above, the brachial plexus, then the subscapularis muscle, the scapulo-humeral articulation, and the tendon of the latissimus dorsi muscle. On its inside it has, above, the first two ribs, below, the serratus magnus muscle.

It is imbedded in a very loose cellular tissue, and is surrounded by the axillary glands, and is attached but feebly to the adjacent parts, excepting a small portion of its upper part. As in this place it rests on the first and second ribs, it may easily be compressed whenever an operation near or within the scapulo-humeral articulation requires.

§ 1403. Several branches, which are not very constant, arise from this artery. The principal, regarded from above downward, are the external thoracic arteries, the inferior scapular artery, and the circumflex arteries. These branches vary in respect to volume, number, and origin, because sometimes many of them arise by a common trunk, and again sometimes one or more come much lower than usual from the brachial artery, or finally in some cases by a trunk in common with the deep brachial artery.

Besides these branches the axillary artery also gives off, in part or entirely, far outward above, one or more of the external thoracic arteries, the transverse scapular artery, so that the principal portion of this latter artery arises at its usual place, but its smallest branch distributes itself to the subscapularis muscle. This anomaly is very remarkable, because it gradually leads to another, which is much greater, where the transverse scapular artery is entirely deficient, or at least is very small ; so that the branches usually given to the muscles of the scapula come from the superficial scapular artery.

I. EXTERNAL THORACIC ARTERIES.

§ 1404. The external thoracic arteries (A. thoracicce externce, s. alares) vary in number from three to six.

Some arise from the inside, others from the outside of the axillary artery.

§ 1405. The former are usually smaller than the latter. They go principally to the superior external intercostal muscles, to the pectoralis minor muscle, to the axillary and thoracic glands, and go downward and forward even to the skin. Sometimes we find only one, and again there are two, which are then much smaller. One of these two arteries, and when there is only one, that one usually arises highest from the trunk of the axillary artery ; it is then termed the superior external thoracic artery (A. thoracica externa suprema, s. prima), and is also called the small external thoracic artery {A. thoracica externa minor), because it is always smaller than the others.

§ 1406. The second external thoracic artery is rather constant and is called the acromial artery ( A . acromialis). It arises from the outside of the axillary artery and is sometimes single and sometimes double. In the latter case, some of the branches usually given off by the single trunk generally arise very near each other, from the axillary artery.

This artery gives off, first, upward and forward and upward and outward, small branches which go to the subclavius muscle ; second, others below, which go to the inner part of the upper edge of the deltoides muscle and also to the upper part of the capsular ligament of the shoulder, where they anastomose below the acromion process with the branches of the superior scapular artery.

Larger and more numerous branches arise forward, inward, and downward, above and below the pectoralis minor muscle ; they enter this muscle and also the pectoralis major muscle from within and without, and are distributed principally in them.

Others, which pass on the pectoralis minor muscle, go outward and forward toward the anterior and internal edge of the deltoides muscle, intc which they penetrate from below upward, and extend to the capsular ligament of the scapulo-humeral articulation, on the surface of which they anastomose with the preceding and also with the branches of the inferior scapular artery and the anterior circumflex artery. They penetrate also to the posterior muscles of the scapula and to the subscapularis muscle.

A constant- branch descends along the inner edge of the deltoides muscle, between it and the pectoralis major muscle, at the side of the cephalic vein. This branch is always considerably large, and it arises sometimes directly from the axillary artery, but then it comes below all the others from which it is very remote, and no longer proceeds between the deltoides and the pectoralis major muscles, but descends below the latter, between the coraco-brachialis and the two heads of the biceps flexor muscle, and gives off considerable branches to these two muscles.

Other branches, which are still lower, go to the axillary glands, to the serratus magnus, and sometimes to the trapezius muscle.

§ 1407. The third, or, when the first or the second or both are double, the fourth or the fifth external thoracic artery, the long thoracic, or the external mammary artery ( A . thoracica externa longa , mammaria externa) is given off so constantly by the subscapular artery that it should never be described as a separate artery. We shall mention it hereafter.

§ 1408. Not unfrequently two branches, which arise from the subscapular artery, come directly from the axillary artery and form a third, fourth, or fifth external thoracic artery, which is distributed to the subscapularis muscle.

IX. SUBSCAFULAR ARTERY.

§ 1409. The subscapular artery, the inferior or common scapular artery (A. subscapularis , scapularis inferior , infra-scapularis , scapularis communis) is generally the largest branch of the axillary artery and sometimes equals this trunk in size. It arises near its inferior extremity, at the lower edge of the tendon of the subscapularis muscle ; so that its origin is covered by the brachial plexus. It is rarely given off lower down.

Its origin is very constant, and when it arises from the inferior thyroid artery it is one of the rarest anomalies, and occurs certainly only in regard to its upper part.

The volume and number of its branches vary. In its greatest development it gives off, first, the final external thoracic arteries, which we have already described, which are its first branches, and which go upward and backward and are distributed in the infraspinatus muscle ; 2d and 3d, one or two circumflex arteries of the arm ; 4th, even the deep brachial artery in whole or in part ; 5th, the long external lateral thoracic artery (§ 1407), more rarely the second, third, and the fourth branches, usually the first and the fifth.

After giving off the first subscapular branches, the artery proceeds inward and downward and divides into two branches, an inferior descending branch and a superior, which is larger, goes backward and is the continuation of the trunk, and is called the circumflex artery of the scapula (A. circumflexa scapula,).

The circumflex artery of the scapula, shortly after giving off the ascending branch, sends off several beside, some of which are large and others small, to the outer edge of the subscapularis muscle, to the teres minor and major muscles, to the axillary glands, the skin of the axilla and of the back, and to the subscapularis muscle. It afterwards curves around the neck of the scapula, passes on its posterior face, where it is called the dorsal artery of the scapula ( A . dorsalis scapula ), when it is very much developed, penetrates partly into the bone, and ascends partly also upward and inward into the subscapularis muscle, advances on the neck of the scapula, and anastomoses with the acromial and with the superior scapular arteries ; finally, when the latter is smaller or deficient, it re-ascends below the spine of the scapula into the supra3pinalis fossa, and distributes branches to the supraspinatus and likewise to the trapezius muscle.

When it is less developed it does not penetrate deeply between the scapula and the infraspinatus muscle, but only into the posterior part of the deltoides muscle, and anastomoses with the preceding arteries on the acromion process and on the anterior edge and even in the substance of the infraspinatus muscle.

The descending branch goes inward, backward, and downward, along the external wall of the chest, in the broad muscles of the back, the lower part of the serratus magnus muscle, the intercostales muscles, the tho- • racic glands, the lower part of the subscapularis muscle, and several of the axillary ganglions.

The portion of this branch which is distributed in the serratus magnus muscle is the long external thoracic artery, which very rarely arises from the trunk of the axillary artery.

III. CIRCUMFLEX ARTERIES OF THE ARM.

§ 1410. There are two circumflex arteries of the arm (A. circumflexa, s. articidares humeri ), an anterior and a posterior.

a. Anterior circumflex artery of the arm.

§ 1411. The anterior circumflex artery of the arm (A. circumflexa anterior humeri , s. articularis anterior) often arises a little higher than the posterior, sometimes also much higher, in some cases at the same height, and sometimes still lower.

It is always much smaller than the latter, but it rarely arises from it or from the subscapular artery(l). It comes very constantly from the outer and anterior side of the axillary artery, a little above the upper edge of the tendon of the latissimus dorsi muscle. It goes outward on the anterior part of this tendon, directly on the humerus, below the common tendon of the biceps flexor and of the coraco-brachialis muscles, to which it gives ramuscules, and also to the periosteum, and divides into upper and lower branches. The latter are fewer and smaller than the former ; they turn inward, some go partly to the internal portion of the deltoides muscle, where they anastomose with the posterior circumflex artery, while the others pass downward on the tendon of the latissimus dorsi muscle, to which they give branches, and anastomose with the recurrent branches of the superficial brachial artery.

(1) We have never seen it arise from the deep brachial artery, of which Mayer (p. 123) asserts it is sometimes a branch.

The upper branches are larger and more numerous, and proceed directly on the humerus ; they ascend toward the upper part of the humerus and give ramifications to this bone, expand in the scapulohumeral articulation, penetrate to the supraspinatus and the infraspinatus muscles, and anastomose with all the arteries of the shoulder which arise from the subclavian and the axillary arteries.

Sometimes another analogous artery exists, which distributes its branches principally to the latissimus dorsi, to the upper part of the biceps flexor, and to the brachialis internus muscles. This artery is frequently only a branch of the anterior circumflex artery.

b. Posterior circumflex artery of the arm.

§ 1412. The posterior circumflex artery of the arm (Jl. circumflcxa humeri posterior) is always much larger than the preceding. It arises from the subscapular or from the deep brachial artery by a common trunk, which varies in length but is never very long, more frequently than from the axillary artery. It very rarely forms a common trunk with the anterior circumflex artery, and when this anomaly occurs, the subscapular artery also arises from this trunk. In the former case it arises no higher, or at most not much higher, than when it comes directly from the axillary artery. But when it comes from the axillary artery it is lower than usual by the length of the whole tendon of the latissimus dorsi muscle, sometimes by about two inches ; for in all the cases at least where we have observed this arrangement (which, so far from being rare, is perhaps the most common), the deep brachial artery arose as usual. The posterior circumflex artery is then reflected from below upward, behind the tendon of the latissimus dorsi muscle, and ascends between the two heads of the biceps flexor muscle until it comes a little above the upper edge of this tendon, that is, until it rises as high as its normal origin. It then goes backward to turn on the humerus. We have sometimes seen the deep brachial artery arise very high and near the posterior circumflex artery ; but we have never found that it then came from the same trunk as the latter, which has led us to think that when these two vessels arise from a common trunk we must not consider the deep brachial artery as a branch of the postenor circumflex artery, as Murray(l) and Sœmmerring(2) have done, but we must regard the posterior circumflex artery as a branch of the deep brachial. (3)

The posterior circumflex artery is reflected outward and forward on the neck of the humerus, between this bone and the long head of the triceps extensor muscle. Proceeding onward, it distributes branches to this long head, to the capsular ligament of the scapulo-humeral articulation, to the teres minor and to the outer head of the triceps muscle. After giving off these branches, which are proportionally very small, it proceeds inward on the inner face of the deltoides muscle, in which it is entirely lost, and of which it is the principal artery. It anastomoses behind and above it with the anterior circumflex, the subscapular, and the superior scapular arteries.

The axillary artery sometimes gives off, above or below these two arteries, some small branches, which enter the biceps flexor, the long head of the triceps, the teres major, and the latissimus dorsi muscles.

III. BRACHIAL ARTBRY.

§ 1413. When the artery of the upper extremity leaves the axilla at the upper edge of the tendon of the latissimus dorsi muscle, it is called the brachial humeral artery (*/2. brachialis, s. humeraria). It goes between the insertions of the teres major and latissimus dorsi muscles and the coraco-brachialis, which it covers, to the inside of the biceps flexor muscle and to the inner face of the arm ; so that it] crosses the direction of the humerus and becomes more superficial the farther it descends, since toward its lower extremity it is covered only by the brachial aponeurosis and the median vein and the skin. Its upper part rests directly on the humerus, and the lower on the brachialis intemus muscle. It usually extends to the anterior face of the humero-cubital articulation, near which it terminates in most subjects. It not unfrequently however terminates higher, and sometimes does not exist at all, and then the branches usually given off in the elbow arise in the axilla.

The largest and’uppermost branches go inward ; they form the deep brachial artery or arteries. The origin of this artery, especially when it gives off branches which usually come from the axillary artery, as particularly the posterior circumflex artery of the arm or the subscapular artery, may often be considered as a point where the brachial artery divides into two branches, a superficial, which is the continuation of the trunk, and a deep branch.

(1) Descript, art. in tab. redacta, p. 41.

(2) Sœmmerring-, Gcfâsslehre, p. 206.

(3) This remark has not escaped Mayer, who says ( loc . cit., p. 123) that one or even both the circumflex arteries arise from the deep brachial artery in rare cases.

§ 1414. The deep brachial or external collateral artery, Grand musculaire du bras, Ch. (Jl. profunda humeri , s. brachii , s. collai er alis magna, s. superior), usually arises below the lower edge of the latissimus dorsi muscle, above the small head of the triceps extensor muscle. It accompanies the radial nerve, which it almost always covers, penetrates between the three heads of the triceps muscle, to which it gives branches, turns from within outward upon the humerus, so that its lower extremity is situated on the outside of this bone, and commonly terminates at the articulation of the elbow, where it is distributed to the supinator longus and the extensor carpi radialis muscles. It also sends branches to the brachialis internus and to the anconeus muscle, supplies the nutricious artery of the humerus near the centre of its course, and having come to the outside of the elbow, it penetrates into the anconeus muscle, where, termed the collateral radial artery ( A . collateralis radialis, s. communicans radialis a profunda ), it anastomoses with the recurrent branch of the ulnar artery. One of these branches, which sometimes arises from the brachial artery, always lower than it but directly under it and sometimes a little distance from it, and which is always smaller, goes farther forward, descends between the long and short portions of the triceps to which it gives branches, anastomoses with the inferior lateral branch of the brachial, and communicates, under the name of the collateral ulnar artery [A. collateralis ulnaris, s. communicans ulnaris a profunda ), with the recurrent branch of the interosseous and ulnar arteries, on the inner and posterior face of the humero-cubital articulation.

Thus the deep brachial artery is distributed principally to the extensor muscles of the fore-arm. It anastomoses above with the subclavian and below with the trunk of the brachial artery and with the arteries of the fore-arm.

§ 1415. Below or above the deep brachial artery, when it is single, or even between it and the collateral ulnar artery, when the latter forms a distinct trunk, we usually see'arise a branch, which goes to the longer portion of the triceps muscle and which anastomoses with the posterior circumflex artery of the arm. This branch sometimes arises from the deep brachial artery. The brachial artery then gives off, forward, outward, and backward, at right angles, about twelve very short differently sized branches, which penetrate into the biceps and the brachialis internus muscle. Some of them go only to one of these muscles, but most of them are common to both. One of the largest, which arises from the posterior and internal part of the brachial artery, about two inches above the elbow, is called the large anastomotic or internal collateral branch, or more properly the inferior anastomotic branch, or the inferior deep brachial artery ( R. anastomoticus magnus inferior, s. A. profunda inferior ) ; the first of these terms is applied to it because it establishes a communication between the trunk of the brachial artery and the arteries of the fore-arm. It proceeds inward, passing on the brachialis internus muscle, to which it gives minuscules, as also to the pronator teres, unites first by a transverse branch with the ulnar branch of the deep brachial artery, which connects it with the recurrent branch of the ulnar artery ; then anastomoses on the posterior face of the articulation of the elbow with the radial branch of the deep brachial artery, and thus forms the dorsal arch of Ihe elbow ( arcus dorsalis articularis cubitalis ), and communicates in this manner with all the anastomosing branches of the fore-arm.

This branch sometimes comes from the radial artery when the latter arises much higher than usual, but its origin is not constant, and then it is sometimes supplied by the continuation of the trunk of the brachial artery — an arrangement which Bichat(l) erroneously considers as a general law in such cases. This branch comes from the ulnar artery much less frequently when the latter is given off much higher than usual. It rarely sends off from its outside, above the articulation of the elbow and directly above where the brachial artery bifurcates to give rise to the two arteries of the fore-arm, a considerable branch, which ordinarily comes from the radial artery, and which is called the recurrent radial artery {A. radialis recurrens). {2)

The two large anastomoses which we have described permit the application of a ligature upon all parts of the brachial artery, without causing any derangement in the circulation and nutrition of the forearm.

IV. ARTERIES OF THE FORE-ARM.

§ 1416. The brachial artery usually divides a little below the elbow, where the tendon of the biceps penetrates between the muscles of the fore-arm, into two branches, the radial and the ulnar artery. This bifurcation rarely and perhaps never takes place much lower, while it not unfrequently occurs higher than usual. Of the two trunks of the fore-arm, the radial is the continuation of the brachial artery as respects its direction, but in most cases it is smaller than the ulnar artery, at whatever height the brachial artery divides. It is nearer thé surface than the latter and arrives at the lower extremity without giving off any considerable branches except one, which arises from its upper part. The ulnar artery, on the contrary, soon divides into two branches, one of which is the proper continuation of the trunk, and the other the interosseous artery.

I. ANOMALIES IN THE ORIGIN OF THE ARTERIES OF THE FORE-ARM.

§ 1417. The brachial artery not unfrequently divides unusually high (§ 1416). (3) This anomaly varies in its mode and degree. The principal laws in both these respects are as follow :

(1) Anat. descrip ,, vol. iv. p. 230.

(2) This arrangement is very rare. We have seen it but once only, and we cannot find it mentioned by any writer. It does not affect the anastomoses around the elbow joint, because in this instance the recurrent radial artery did not arise much higher than usual.

(3) See our Mémoire sur les différentes variétés qu’on observe dans la distribution de l'artère brachiale; in the Journ. conrpl. du diet, des sc. méd., vol. iii. p. 31. — We

a. In regard to mode , we observe three principal differences. In fact, the artery which arises unusually high is sometimes the radial, sometimes the ulnar, and finally sometimes the interosseous artery. Observation confirms what might be admitted on conjecture, that the first of these three anomalies is the most common and the last the rarest ; which evidently depends on the fact, that in producing the first, nature conformed to the primitive type in this respect, that the artery which is generally given off first, that is the radial artery, generally arises higher than usual. In the second anomaly, although the division takes place higher than usual, there is also an inversion, since the interosseous artery comes from the radial artery and the ulnar artery arises above the latter. Finally, in the third the anomaly is still greater, since a vessel usually given off by a branch of the brachial artery, the ulnar artery, arises directly from the trunk.

The ulnar and radial arteries are distinguished from each other when they arise higher than usual, because the former is commonly more superficial than the latter, and it then is frequently situated between the aponeurosis and the skin, an arrangement which, judging from our observations, is not always constant.

But in whatever manner this abnormal division of the brachial artery above its usual point occurs, the vessel which it thus prematurely produces is always situated in the arm, directly at the side of the superficial brachial artery.

b. In regard to the degree, we may consider the anomaly either in itself or in relation to the whole vascular system.

First, considered in regard to itself, it presents several differences, of which the principal are as follow ;

1st. The first degree consists in the existence of abnormal vessels ( vasa aberrantia), greater or less branches, which arise from the upper part of the superficial brachial artery, and empty into its lower part, or, as is more common, into an artery of the fore-arm, particularly the radial artery. In this case both the normal and the abnormal division exist, and the artery of the fore-arm, into which the abnormal vessel empties, arises in fact by an upper and a lower root. The normal type gradually passes to the abnormal formation by the increase of the first of these roots and the diminution of the second, until the latter type is perfect, when the lower root entirely disappears.

2d. A second degree is when the brachial artery divides more or less above its usual place. This division occurs in fact in all parts between the axilla and the humero-cubital articulation. The three arteries of the fore-arm differ from each other in this respect, that although the radial artery arises unusually high much more frequently than the ulnar artery, still when the anomaly exists, the ulnar artery comes from a higher point, particularly from the axillary artery itself, while the radial artery is given off near the middle of the arm. When the interosseous artery is abnormal in this respect, it arises either from the angle of the bifurcation as usual or from a higher point.

have there given our own observations and the principal of those collected by other authors.

Second, considered in regard to the whole vascular system, this anomaly exists on one side only or on both sides at once. Bichat asserts that he has seen the first case oftener than the second, but our own observations and those of other anatomists prove the contrary.

This anomaly however is by no means the same on both sides in regard to the manner and the degree, and we more commonly observe differences in one or the other of these two relations than the contrary, or a perfect similitude between the two sides of the body. We cannot yet say if the anomaly is observed on the leftside more frequently than on the right when it is seen only on one side, and if it is more distinct on this side than on the other when it occurs on both sides, although this seems very probable, reasoning from the difference between the formative types of the two sides, and also from other anomalies, and from the observations which we have been able to collect.

All these anomalies are equally important in a physiological or surgical point of view. They concern physiology, because they imitate the two superficial veins of the arm. The surgeon ought always to observe them carefully, because they increase the chance of injury to the arteries of the arm, and because, when the course of the blood in the brachial artery is in any manner interrupted, it re-establishes the circulation in the upper extremity more easily.

II. RADIAL ARTERY.

§ 1418. The radial artery (A. vadialis) is usually much smaller and nearer the surface than the ulnar artery ; but in considering its direction only, it is a continuation of the trunk of the brachial, artery. It is much smaller when the recurrent radial artery arises from the brachial artery. Less frequently still it is larger, which occurs when the interosseous artery arises from it instead of coming from the ulnar artery as usual.

This artery descends a little obliquely from behind forward, along the radius, to the radio-carpal articulation, where it glides under the tendons of the extensor digitorum communis muscle, and penetrating into the palm of the hand, between the first and second metacarpal' bones, it anastomoses with the ulnar artery.

§ 1419. The first branch of the radial artery is generally the recurrent radial artery (A. recurrens radial is) ) when the latter does not come from the brachial artery, which rarely happens. It arises as rarely from the ulnar artery, which we have observed only a few times, when the radial artery arose much higher than usual ; even then the recurrent radial artery can be considered only as divided into two portions, for the radial artery gives off a muscular branch, which is detached higher than usual. In the most frequent cases, in fact, the brachial artery divides into three trunks and gives off the recurrent branch at the place with the two others ; but this artery constantly arises very high from the radial artery, which even in the adult passes through but a very few lines before it is sent off. It is always the largest branch which this artery gives- to the fore-arm ; so that we may say that the radial artery, as soon as it arises, divides into two branches, one of which continues to proceed in the direction of the trunk and is the proper radial artery, and the other is smaller and is the recurrent artery. The latter gives branches to the pronator teres, the supinator longus, the supinator brevis, and the extensor carpi radialis muscles, to the capsular ligament, to the inner portion of the triceps extensor, and is reflected from below upward, between the supinator longus and the extensor carpi radialis longus, to anastomose with the recurrent radial artery given off by the deep 'brachial artery on the inner tuberosity of the humerus.

At the same place, sometimes a little higher, the radial artery gives off a small recurrent branch, which goes into the lower part of the inner portion of the brachialis internus muscle. It then gives off from its outer and inner sides, and at right or nearly right angles, and very near each other, small branches, almost uniform in size, and at least forty in number. Of these, the internal are distributed to the pronator teres, the flexor carpi radialis, the flexor digitorum sublimis, the flexor pollicis longus, the pronator quadratus muscle, and the capsule of the radio-carpal articulation ; while the external are distributed in the pronator teres, the pronator quadratus, and the extensor carpi radialis.

§ 1420. Toward the lower end of the radius, the radial artery constantly gives off a branch, which passes on the radial edge of the carpus, enters into the palm of the hand, and is called the superficial palmar artery (A. superficialis voice). This branch is always situated below the palmar aponeurosis, and proceeds toward the ulnar edge of the hand to meet the ulnar artery. This branch is sometimes and not rarely so large, that we have reason to say that the radial artery bifurcates in the place where it arises to produce it and also the continuation of the trunk which goes on the back of the hand. When this branch is small, it is frequently but not always distributed only to the small muscles of the thumb. When it is considerable, it usually but not always anastomoses with the ulnar artery to form the superficial palmar arch ( arcus volaris superficialis ), and contributes as much as the latter to produce it.

Sometimes the superficial palmar artery arises much higher than usual and proceeds in the same direction as the radial artery, with which however it cannot be confounded, as it is more superficial and less fixed in its situation.

It is essential to remember this circumstance, in order not to be in error when we wish to ascertain the state of the pulse by feeling the radial artery.

§ 1421. When the superficial palmar artery concurs to form a superficial palmar arch, it gives off very distinctly some digital palmar arteries (A. digitales volares). In two preparations now before us it gives off the digital palmar artery of the thumb (A. digitalis volaris idnaris pollicis) and the digital palmar artery of the index finger ( A . digitalis volaris radialis indicis ).

Usually, when the superficial palmar artery is not very small, the superficial palmar arch is double, because, beside the large anastomosing anterior twig of this branch, we find another, which is smaller and more transverse and posterior.

However small the superficial palmar artery maybe, and even when it does not contribute to form the superficial palmar arch, it however is never entirely deficient, and always anastomoses with the continuation of the trunk of the radial artery at the bottom of the palm of the hand. We have never seen it arise except under the pronator quadratus, or at least toward its posterior edge, and constantly below the place where the radial artery rests almost directly on the radius. We must except some but not all those cases, where the radial artery arises from the brachial artery extremely high, and, imitating the type of the latter, bifurcates unusually high, for instance near the elbow.

§ 1422. After giving off the superficial palmar artery, the continuation of the trunk of the radial artery goes usually on the back of the hand, passing between the styloid process of the radius and the os trapezium ; but sometimes it is reflected higher on the outer face of the radius and of the fore-arm, and produces the following branches :

1st. Branches which go to the ligaments of the carpus and also to the flexor brevis pollicis and the abductor pollicis proprius.

2d. The dorsal artery of the thumb ( A . dorsalis pollicis), which arises from its outside, extends along the radial edge of the metacarpal bone of the thumb and of all the phalanges of this finger, anastomoses with its digital palmar artery, and rarely arises from the superficial palmar artery given off by the radial artery.

3d. The dorsal artery of the carpus (A. dorsalis carpi radialis) arises from the inside of the radial artery, more or less opposite the preceding, goes transversely toward the ulnar edge of the hand, and passing under the tendons of the extensor muscles, directly on the dorsal ligaments of the carpus, anastomoses with some small branches of the radial artery which were given off higher than the latter, then with the extremity of the interosseous artery, finally with the dorsal branch of the ulnar artery, and thus forms the dorsal arch of the carpus ( arcus dorsalis carpi), which resembles an arch less than a net-work with large meshes.

§ 1423. The dorsal interosseous arteries (A. dorsales interosseœ) arise principally from this arch. They proceed from behind forward in the spaces between the metacarpal bones from the second finger to the fifth, go to the external interosseous muscles, and are continuous, first, forward, with the corresponding digital arteries between the posterior extremities of the first phalanges, in the*place where the trunk of these arteries bifurcates ; second, with the inferior metacarpal arteries, whence results

a large circle of anastomoses between the dorsal and the palmar branches of the arteries of the fore-arm.

§ 1424. Next come smaller ramifications, which enter the abductor indicis proprius muscle and the ligaments of the carpus ; then, between the posterior extremities of the first two metacarpal bones, arise the dorsal cabital artery of the thumb (A. dorsalis ulnaris pollicis) and the dorsal radial artery of the index finger (A. dorsalis radialis indicis ), which arise sometimes separately and sometimes by a separate trunk.

§ 1425. When the radial artery has given off these branches, it enters into the palm of the hand between the first two metacarpal bones and the adductor indicis muscle, goes transversely toward the ulnar edge, and anastomoses with the ulnar artery, which meets it so as to form a deep palmar arch ( arcus volar is profundus), and contributes to produce it more than the latter. When passing on the posterior extremity of the metacarpal bone of the index finger, it gives rise to the large artery of the thumb ( A . princeps , s. magna pollicis). The latter divides sometimes into the palmar radial and the palmar ulnar artery of the thumb ( A . volar is pollicis radialis et ulnaris ), sometimes furnishes only one of these two branches, while the other arises near the superficial or from the deep palmar arch ; but it always anastomoses by one or two large branches with the radial and the ulnar dorsal arteries of the thumb, even when the corresponding palmar arteries do not arise from it.

The radial artery rarely divides, when passing through the first interosseous space, into two branches, one of which is the continuation of the trunk and goes into the palm of the hand, while the other is smaller, passes over the internal belly of the first external interosseous muscle, and anastomoses with the superficial palmar arch, giving origin to the palmar cubital artery of the thumb (A. volaris ulnaris pollicis), where it divides into this artery and the palmar radial artery of the index finger ( A . volaris radialis indicis), which formation is remarkable because it strengthens the resemblance with the arteries of the other fingers, as this dorsal branch then represents the first dorsal metacarpal artery, which is the largest. Sometimes but very rarely these arteries do not arise from the large artery of the thumb, but from the superficial palmar arch and directly from the superficial palmar radial artery. In this case the palmar and the large arteries of the thumb, which are proportionally smaller, give off only the dorsal arteries of the thumb. Nevertheless, we have never seen this arrangement except when the radial and the palmar radial arteries arose unusually high.

Even at the place where the large artery of the thumb arises, and only little more on the anterior side of the radial artery, a very constant branch arises, which however varies in size ; this goes inward and passes directly on the palmar face of the second metacarpal bone, gives branches to the adductor pollicis muscle, and contributes more or less to form the palmar arteries of the index finger. This however is not always the case ; so that the radial artery of this finger always comes from the branch of which we were speaking, as Scemmerring pretends ; for we have sometimes seen, notwithstanding the considerable size of the latter, the radial artery of the index finger coming from the superficial palmar arch. We may then, in order to express the analogy between it and the large artery of the thumb, term this branch the large artery of the index finger {A. princess indicts').

Wo shall describe the deep palmar arch when speaking of the ulnar artery.

III. VLNAR ARTERY.

§ 1426. The ulnar artery (A. ulnaris, s. cubitalis) is generally the largest of the two branches produced by the bifurcation of the brachial artery ; it goes toward the ulna sooner after arising, passes below the pronator teres, and proceeds toward the hand, along the ulna, between the flexor ulnaris and the flexor digitorum profundus muscles, and is always situated deeper than the radial artery. It gives off near its origin a small or large branch, the anterior recurrent ulnar artery, which penetrates to the lower extremity of the inner portion of the triceps extensor and also into the upper extremity of the pronator teres, and corresponds to a similar branch given off by the radial artery.

§ 1427. It then sends off the recurrent or the posterior recurrent ulnar artery (A. recurrens ulnaris, s. cubitalis), which is generally much larger than the preceding, and proceeds from below upward between the flexores digitorum sublimis and profundus and the flexor ulnaris, distributes branches to these muscles, penetrates through the latter, and ascends between the inner condyle of the humerus and the olecranon process, and unites with the inferior and internal collateral artery which comes from the brachial artery, and thus forms the largest anastomosis which exists around the humero-eubital articulation. This artery- always arises much low’er than the recurrent branch of the radial artery. It comes very constantly from the ulnar artery, when the latter arises as usual from the brachial artery ; at least we have never seen it arise directly from the humeral artery, as does the recurrent radial artery, which undoubtedly must be attributed to its arising so low. On the contrary, in all those cases where the ulnar artery ascended unusually high, the recurrent artery was not given off by it but by the interosseous artery ; so that then even the anomaly approached as near as possible the normal formation.

§ 1428. Soon after giving off this branch, the ulnar artery divides into two others, the proper ulnar artery and the interosseous artery (A. interossea ), which is usually smaller than the other. The latter is rarely given off by the brachial artery, either at the usual place of its bifurcation(l) or above this point.(2) When the ulnar artery arises unusually high, the interosseous artery is a branch of the radial artery,, whence it arises in the same region of the fore-arm, although it comes from a different artery.

(1) Barclay, Description of ihe arteries of the human body; lathe Edinb. Med. and Surg. Journ., vol. viii p. 468.

(2) Monro, Outlines of Anatomy, vol. iii. p. 304,

From these two causes the ulnar artery is much smaller than usual when it arises uncommonly high. This diminution of caliber is sometimes observed in it, although its origin is not abnormal, because the interosseous artery, although very rarely, arises from the radial.

The interosseous artery gives off near its origin one or two very constant branches, which descend into the upperpartoftheflexoresdigitorum sublimis and profundus, into the flexores carpi radialis longus and brevis muscles, and the pronator teres. Lower down it divides into two branches, nearly equal in size, one of which is a little larger and is a continuation of the trunk, and descends on the anterior face of the interosseous ligament, while the other passes above the upper edge of this ligament to go to the dorsal face of the fore-arm. This branch is the superior perforating artery (A. perforons prima suprema), which soon divides into two branches. The smaller, which is however considerable, is called the recurrent interosseous artery {A. recurrens interossea ), reascends above the extensor carpi ulnaris muscle, between the radius and the ulna on one side and the anconeus muscle on the other, and empties into the dorsal arch of the articulation of the elbow. The larger descends between the origin of the extensor longus and the abductor pollicis longus on the one side, the extensor digitorum and the extensor carpi ulnaris on the other, along the ulna to its lower extremity, and in its course gives off numerous branches to the muscles which we have mentioned.

§ 1429. The trunk of the interosseous artery descends in most of its extent on the anterior face of the interosseous ligament, between the two bones of the fore-arm, a little nearer the ulna than the radius, gives small twigs to all the flexor muscles, and also supplies six or seven branches, the inferior perforating arteries (A. perforantes minores inferiores ), which pass through the interosseous ligament, glide on the posterior face of the fore-arm, and are distributed in the extensor muscles. The arterial trunk terminates in passing above the upper edge of the pronator quadratus to the dorsal face of the fore-arm, where it divides into three or four branches, nearly equal in size. One or two of these branches are distributed partly in the extensor and the abductor pollicis and partly also pass under the tendons of these muscles, resting directly on the bone, turn on the radius, and anastomose with the branches of the radial'artery. The second or the third, which retrogades on the ulna, anastomoses with the superior perforating artery. The third or the fourth, which is the continuation of the trunk, descends between the two bones of the fore-arm and forms the dorsal arch of the carpus ( arcus dorsalis carpi) on the back of the carpus, and divides into a middle and at least two lateral ramuscules, which communicate with, the carpal branches of the radial and ulnar arteries.

§ 1430. The trunk of the interosseous artery rarely gives off a long branch, which descends between the flexor muscles of the fingers to the hand and contributes to form either the superficial palmar arch or the arteries of the thumb. This is seen particularly when the ulnar artery arises higher than usual, a very remarkable circumstance, as it shows an effort to approximate the anomaly to the normal formation.

§1431. The ulnar artery, after giving off - the interosseous artery, sends off like the radial, at short intervals, numerous ramuscules, which are distributed to the muscles between which it descends, the flexors of the fingers, and the extensor carpi ulnaris muscle. Near the lower extremity of the ulnar and about an inch above the radial artery, it divides into two branches, the larger of which is the continuation of the trunk, while the other is smaller and is called the dorsal ulnar artery ( A . dorsalis ulnaris , ramus dorsalis ab ulnan). The latter is reflected above the tendon of the flexor ulnaris muscle, on the lower extremity of the ulna, sends branches to the flexor ulnaris and to the pronator quadratus muscle, also to the ligaments of the carpus, anastomoses with the dorsal branch of the radial and with the interosseous artery, gives rise to the dorsal arch of the carpus, and terminates in the fourth internal interosseous muscle, also in the muscles of the index finger, especially the abductor muscle.

§ 1432. After giving some small branches to the palmar ligament of the carpus, the ulnar artery divides, near the posterior extremity of the fifth metacarpal bone, into two branches, the superficial and the deep palmar artery ( ramus volaris superficialis el profundus.)

IV. PALMAR ARCHES.

§ 1433. There are two palmar arches ( arcus voice), a superficial and a deep.

The superficial palmar branch of the ulnar artery is usually much larger than the deep. It passes above the tendons of the flexor muscles which previously covered the ulnar artery, advances immediately below the palmar aponeurosis toward the radial edge of the hand, and anastomoses with the superficial palmar branch of the radial artery, which it always exceeds in volume, even when the latter is unusually large. These two branches join and form the superficial palmar arch ( arcus superficialis voice). This arch is not unfrequently formed entirely by the ulnar artery, which does not then anastomose with the pajmar branch qf the radial artery, or communicates with it only by some trifling ramuscules.

The collateral arteries of the fingers {A. digitales) arise from the superficial palmar arch, but not constantly in the same manner. The only rule which we can establish in this respect is, that most of the digital arteries arise directly or indirectly from the superficial arch, from the deep arch, or from both at once, and always arise two and two from a single trunk ; so that this single trunk extends from the arch to the extremity of the first phalanx and there divides into two branches, which are unequal and often disproportional in size, which always belong to two different fingers and never to one only. These branches proceed on the palmar face of the fingers, along the radial edge of one and the ulnar edge of the other. Each finger thus receives two collateral arteries, the ulnar of which is always the larger.

The little finger usually receives a proper or .special ulnar artery, the first branch of the superficial palmar arch which goes to it, proceeding along the flexor minimi digiti brevis muscle, to which it sends numerous ramuscules.

Some distance from this branch, and very near each other, arise three very constant arteries, the. second, the third, and the fourth collateral arteries, which go, the first to the radial side of the fifth finger and the ulnar of the fourth, the second to the radial side of the fourth and the ulnar side of the third finger, and the last to the ulnar side of the second and to the radial side of the third.

Farther, we generally find a fourth common collateral artery, which divides into the artery of the radial side of the index finger and the artery of the ulnar side of the thumb.

This arrangement presents only a few unimportant anomalies, the principal of which are :

Sometimes the second collateral artery, the ulnar branch of the fifth finger, belongs not so much to the superficial as to the deep palmar arch, of which it is the posterior part, — that by means of which this arch communicates with the other ; so that it must be considered as an anastomosing branch between the two arches. The fourth collateral artery, which goes to the radial side of the third and the ulnar sid,e of the second finger, sometimes presents the same anomaly. These two differences arise because the two arteries always communicate with the deep arch by large anastomosing branches, while the other two middle collateral arteries are more insulated and more independent.

The union of several digital arteries in a common trunk, which is always very short, forms a second anomaly. To this there is a gradual transition by a case which is sometimes observed, viz. the approximation of two branches to each other.

Thus we have often seen coming from a common trunk the first and second, the third and fourth, or the fourth and fifth, which then went only to the radial side of the index finger. When the artery of the little finger does not form a small distinct trunk, but comes from the second, the common trunk is a little longer than that which appears when the branches are united, and the second goes almost always to the ulnar side of the fourth finger and the radial side of the fifth.

§ 1434. The deep or the smallest ulnar artery turns deeply from behind forward on the flexor minimi digiti brevis muscle, goes always outward toward the radial side of the hand, so that it proceeds transversely on the internal interosseous muscles to meet the deep palmar artery, with which it anastomoses, and forms the deep palmar arch (arcus palmar is profundus). This arch is sometimes larger and sometimes smaller than the superficial, but smaller more frequently than larger, and its caliber is always greater on the radial than on the ulnar side, because the radial artery concurs to form it more than the ulnar artery. It is always situated farther back than the superficial arch, and is placed directly before the posterior extremity of the metacarpal bones.

§ 1435. The deep palmar arch produces,

1st. From its anterior side or its convexity, the palmar interosseous arteries (A. interossece volares ), or the inferior perforating arteries (A. perforantes inferiores), which are the largest of all its branches.

These arteries go to the internal interosseous muscles in the spaces between the metacarpal bones, give branches to the muscles in these regions, and one or the other at least, and sometimes all. anastomose at their anterior extremity with the collateral arteries of the fingers, where the latter bifurcate, and also with the superior interosseous arteries.

They correspond to the collateral arteries of the. fingers, but are usually much smaller. The first however is generally much more developed than the others. Hence we have prop'osed to term it the large artery of the index finger (A. indicis princeps) (§ 1425). Sometimes howeyer other arteries among the inferior interosseous arteries are unusually large ; so that they are as large or nearly as large as the common trunks of the collateral arteries which arise from the large arch, and the digital arteries also arise as much and even more from the deep than from the superficial arch.

Sometimes but more rarely they exceed almost all the collateral arteries of the fingers in volume, and the palmar arteries of the fingers arise more than they from the superficial arch, as is frequently the case with the index and little finger.

2d. The superior ox posterior perforating arteries (A. perforantes, s. posteriores , s. superiores) arise from the convexity of the deep palmar arch. They penetrate between the posterior extremities of the metacarpal bones, give ramifications to the posterior part of the lumbricales muscles, and come on the back of the hand, where they anastomose with the anterior part of the dorsal arch of the carpus and with the superior metacarpal arteries, which are given off by this arch less frequently than by them (§ 1432).

§ 1436. Thus the two palmar arteries concur simultaneously to produce the digital arteries. The superficial arch contributes most to the origin of the palmar branches of the third, of the fourth, fifth, and of the ulnar side of the index finger ; the deep, on the contrary, assist more in forming the palmar branches of the thumb and of the radial side of the index finger. Sometimes however the latter arise entirely from the superficial arch, but this is true of the radial artery of the index finger and the ulnar artery of the thumb more frequently than of the radial artery of the thumb. In this case the two branches arise by a common trunk. When all the digital arteries, not excepting those of the thumb, come from the superficial palmar arch, this divides sometimes at the lower part of the hand into two large principal branches, one of which gives off the twigs which usually arise from the superficial arch, and the other bifurcates to give rise to the principal artery of the thumb and the radial branch of the index finger, which deserves to be remarked, as it shows that nature endeavors to approximate to the normal type even in the greatest anomaly. The superficial palmar artery of the radius does not then exist or is very slightly developed. It sometimes, on the contrary, contributes more than usual to produce the superficial palmar arch, and then it gives off also all the digital arteries ; but the ulnar and the radial arteries are not then always connected, except by a small anastomosing branch, which is sometimes entirely deficient, and each of the two arteries produces only the branches which go to the corresponding side of the hand.

The two palmar arteries anastomose at the bifurcation of the digital arteries and produce the two collateral arteries. They communicate by long branches, which are usually much smaller than the common trunks of the digital arteries. The largest and most constant of these branches are situated between the ulnar artery of the little finger and the common artery of the second and third.

The dorsal arch of the carpus and the deep palmar arch communicate by the posterior or superior perforating arteries and the dorsal interosseous arteries. The last and the inferior interosseous arteries establish a communication between these two arches and the superficial palmar arch.

V. DIGITAL ARTERIES.

§ 1437. Although the digital arteries arise in most cases from the superficial arch (§ 1433), we may however say, that the deep arch (throwing out of view what happens more or less frequently, that some are given off by this latter alone) and the dorsal arch of the carpus contribute to produce them ; so that the obliteration of one of these sources may be easily replaced by the enlargement of the other.

Each finger receives at least four constant branches, two palmar and two dorsal ; the latter are smaller than the others. The two palmar branches anastomose on the palmar side, either on one phalanx only, or on several, or even on all, by one or more transverse branches, the convexity of which is turned a little forward. However, among these anastomosing branches, the only ones which are constant are those which are very much developed on the lower face of the third phalanx and which are usually double. Besides, the palmar branches anastomose with the dorsal by an arch on the back of the phalanges, especially the third. Each palmar artery gives off in its course at least ten or twelve branches, which go to the nerves, tendons, ligaments, and skin. It also gives, from the arch it forms at the extremity of the finger, by anastomosing with that of the opposite side, at least as many ramuscules, which go to to the skin.

Chapter III. Thoracic Portion Of The Aorta

§ 1438 . From the thoracic portion of the aorta or from the pectoral aorta ( aorta thoracica) (§ 1329 ) arise numerous but very small arteries, and hence the aorta after giving them off is not sensibly smaller than when proceeding along the chest after the three trunks have arisen from its arch.

Many of these branches are constant, but others are not ; and they frequently arise totally or at least in part from other arteries.

The former arise from the lateral parts or from the posterior side of the pectoral aorta in its whole length ; the others come principally from its upper and central part and from its anterior side.

A. ANTERIOR BRANCHES.

§ 1439 . The anterior branches of the thoracic artery are principally the inferior bronchial {A. inferiores bronchiales), the esophageal (A. esophageœ), and the posterior mediastinal arteries (A. médiastinales posteriores).

The inferior bronchial arteries which arise from the aorta vary much in number and origin.

They vary in number from two to four. There are commonly two on each side for each bronchia. The inferior are a little larger than the superior. The largest and most constant generally arise an inch below the extremity of the arch of the aorta. The right is almost always a branch from the first intercostal artery of the aorta, which gives it off after coming on the right side of the vertebral column, passing behind the esophagus. . But sometimes it arises directly from the aorta, and the latter frequently gives off on the right a second inferior bronchial artery when the usual one arises from the first intercostal branch of the aorta, or even when the left bronchial artery sends ramifications to the right bronchia. The left, on the contrary, arises directly from the aorta, and passes before the esophagus to go to its bronchia ; but as it is larger than that on the right side, it commonly gives also some branches to the bronchia of the right side.

The small superior bronchial arteries, which are less considerable and inconstant, belong generally speaking more to the left than to the right bronchia.

Besides these ramuscules, which may be called the middle bronchial arteries, each bronchia receives from the subclavian artery (§ 1372 ) or from the corresponding internal mammary (§ 1398 ), branches, called the superior bronchial arteries, which are expanded in its upper part and communicate by large anastomoses with' the middle and inferior bronchial arteries.

Sometimes the aorta gives off only one bronchial artery, which often arises from it in common with the right superior intercostal artery.

The bronchial arteries are distributed not only to the bronchiæ but also in the esophagus, the aorta, the pericardium, and the thymous gland.

§ 1440. The aorta gives off, generally below these arteries, from its anterior part, several esophageal arteries, which vary in number from two to seven and which are always smaller than the bronchial arteries. These arteries communicate with the esophageal branches which arise from the bronchial arteries and also with others, which are given off by the inferior diaphragmatic arteries, with the latter, and with the arteries of the stomach. They anastomose extensively and always by very large branches.

1441. The posterior mediastinal arteries are always small and very numerous. They are distributed partly in the esophagus and particularly in the parietes of the thoracic aorta, and anastomose with each other, and also with the esophageal arteries, and with the branches of the internal mammary artery.

B. LATERAL AND POSTERIOR BRANCHES. INTERCOSTAL ARTERIES.

§ 1442. The inferior and posterior aortic intercostal arteries ( J1 . intercostales posteriores , inferiores ; s. aorticœ) are the lateral and the posterior branches of the thoracic aorta. We find an arterial branch in each intercostal space, but the aorta does not give. off as many as there are spaces; for, 1st, the first and second, or at least the first, usually receive their vessels from the superior intercostal artery, a branch of the subclavian artery (§ 1399).

2d. Several intercostal arteries, particularly the upper and the lower, and sometimes also the middle, although then the upper and lower do not participate in the anomaly, arise by common trunks, both the opposite arteries of the right and left sides, which correspond in respect to the intercostal space into which they penetrate,, as well as those which are situated one above the other on the same side. This -last anomaly is more rare than the first. When two intefcostal arteries arise by a common trunk, we have always observed hitherto that the inferior is the continuation of the trunk and proceeds in its direction, while the superior generally passes before and more rarely behind the neck of the rib to arrive at the intercostal space, in which it is then distributed as usual.

A common trunk usually divides only into two secondary branches, but sometimes also it gives off several, of which the superior aortic intercostal artery(l) gives frequent examples.

(1) In opposition to the superior intercostal, which arises from the subclavian artery.

The fact that the superior and inferior intercostal arteries generally arise by a common trunk, is curious in two respects :

1st. Because it furnishes a new instance of the resemblance between the upper and the lower extremities of the same region.

2d. Because the superior aortic intercostal artery and the superior intercostal which arises from the subclavian artery, especially correspond.

The two arrangements are then a repetition, in the central portion of the vascular system, of the resemblance demonstrated between the upper and the lower part of this system, when we consider the diaphragm as the line of demarkation between the two portions.

Finally, the two series of intercostal arteries are not perfectly similar, and the two intercostal spaces of one side frequently receive their vessels from a common trunk while on the other side they arise separately^ 1)

We generally find on each side eight (2) aortic intercostal arteries because the upper intercostal artery gives them to the first two intercostal spaces, and the third and fourth receive the blood from the branches of the first aortic intercostal artery.

The number of the intercostal arteries is very rarely increased by one, which happens when the upper intercostal artery, usualty furnished by the subclavian, arises directly from the pectoral aorta. (3) This is more frequently the case than that the first aortic intercostal artery is distributed only in the third intercostal space.

The number of these arteries is then one less, and is reduced to seven. Then sometimes the first goes to the second, third, and fourth intercostal spaces ; sometimes, and more frequently, two of the inferior arise by the same trunk.

All the intercostal arteries generally come more from the back side of the aorta than from its lateral part, they arise near each other, and the right and the left at the same height.

They are all detached from the aorta at slightly acute angles, and go upward toward the intercostal space to which they correspond, passing on the bodies of the vertebrae and the necks of the lower ribs.

The distance between their origin and their intercostal space is much greater, and the angle which they make with the trunk is more acute above and more obtuse below in the upper than in the lower. They never, not even the lowest, form a right angle with the aorta.

(1) Bichat is mistaken in saying- that, considered on the two sides, these arteries are almost perfectly similar (An. descript, vol. iv. p. 253).

(2) Bichat asserts erroneously, that there arc usually nine. Murray and Soemmerring are also mistaken in saying there are never less than eight. Mayer is still more in the wrong ; he admits that there are usually eleven aortic intercostal arteries on the right side, and ten on the left.

(3) Monro seems to regard this formation as equally common with the rule (Outline s, p. 322); but it is in fact very rare, a circumstance which is not uninteresting, inasmuch as the pectoral aorta seems to have, directly above the origin of the intercostal artery, a great tendency to contract very much or to close entirely.

These arteries become smaller in proportion as they are lower. It is however necessary to say something more exact on this subject. In fact the first intercostal artery is much larger than the others, partly because it is distributed to a greater number of intercostal spaces, and because on the right side at least it gives rise either partly or wholly to the right bronchial artery.

The right intercostal arteries, from the situation of the aorta on the left side of the vertebral column, are longer than the left, by all the right portion of the vertebra on which they pass.

Near their origin they give ramifications- to the esophagus and generally to all the parts contained in the posterior mediastinum, and divide usually near the head of the ribs into two branches, a posterior and an anterior.

The posterior branch (R. posterior , s. dorsalis) passes through the intercostal space to go backward, gives some ramuscules to the vertebrae, also sends some to the spinal marrow, through the intervertebral foramina, but is distributed principally to the posterior muscles of the trunk situated in the groove between the vertebral column and the ribs, the multifidus spinæ and the longissimus dorsi. Its superficial ramifications reach even to the skin, and it anastomoses by ascending and descending branches with the adjacent superior and inferior dorsal branches.

The anterior , thoracic , or intercostal branch (I?, anterior, thoracicus, intercostalis ) is generally much larger than the dorsal, which exceeds it particularly in volume in the superior intercostal arteries, and which, from its direction, may be considered as the continuation of the trunk ; it proceeds first between the pleura and the posterior part of the intercostalis internus muscle, to which it is feebly united, then passes between the intercostales interni and externi muscles, and soon divides into two branches.

The inferior branch ( R . costalis inferior ) is much smaller than the other, goes forward, along the upper edge of the lower rib, soon passes on the internal face of this bone, gives ramifications to its periosteum, furnishes some, although very few, to the intercostales muscles, and terminates by anastomosing with the upper branches of its trunk and of the intercostal artery which come directly after.

The upper branch ( R. costalis superior) is the continuation of the trunk, and proceeds below the upper rib of its intercostal space in the groove, on its lower edge, goes forward, gives ramuscules to the ribs, to the intercostales, the abdominal, and the dorsal muscles and to the diaphragm, and anastomoses with the anterior intercostal arteries which come from the internal mammary artery, and also with the epigastric and the external iliac arteries.

The first intercostal artery is distinguished from the others by the characters we have already mentioned. It supplies several, and sometimes even three intercostal spaces.

The right and left differ, as the first usually gives off the right bronchial artery while the second is distributed more frequently than it in a third intercostal space.

Although this latter arrangement is not constant, we have never seen the first two intercostal arteries correspond in regard to the former.(l)

Next to the first the last is largest of any, and sometimes exceeds it in size. It arises behind the lumbar portion of the diaphragm ; after giving some branches to this muscle it passes almost entirely below and before it, and, proceeding outward and forward, behind the upper portion of the quadratus lumborum muscle, it divides into several large branches, which are distributed in this muscle and also the broad muscles of the abdomen, then descend to the crest of the ilium, and anastomose frequently with the lumbar and with the circumflex iliac arteries.

The two inferior intercostal arteries often arise by a single trunk, which comes from the posterior part of the aorta. They are sometimes deficient on one or on both sides ; they are then replaced by the first lumbar artery.

Chapter IV. Abdominal Portion of the Aorta

§ 1443. The abdominal aorta gives off in fact fewer branches, but most of them are larger than those which arise from the thoracic aorta. The reason of this is that the abdomen is larger than the chest, and the organs which it contains are also much larger. A farther reason is that all these organs receive their arteries from the abdominal aorta, while those of the thoracic viscera do not all come from the thoracic aorta.

The branches of the abdominal aorta may be divided into anterior, lateral, and posterior. The anterior and the posterior are however, at least in great part, sometimes more and sometimes less lateral than usual.

I. ANTERIOR BRANCHES.

§ 1444. The anterior branches of the abdominal aorta belong almost exclusively to the digestive organs. There are usually three, the cœliac , the superior, and the inferior mesenteric arteries. Sometimes however we find only two, the first two arising by a common trunk. But they oftener exceed three.

(1) As Soemmerring seems to admit (p. 249), since he thinks that the first two intercostal arteries are large because they give off the bronchial arteries. Bichat agrees witli us (p. 250) on this subject.

The aorta on coming into the abdomen, having passed through its opening in the diaphragm, usually gives some small branches to the pillars of this muscle, to the thoracic canal, and to the renal capsules.

It seldom gives off the inferior diaphragmatic arteries, either separately or by a common trunk. These arteries more frequently arise from the cœliac artery, consequently they will be treated of when speaking of that artery.(l)

I. C CELIAC ARTERY.

§ 1445. The cœliac artery, Opislro gastrique , Ch. (A. cœliaca),(2) is usually the largest, and arises the highest, as it comes off at a right angle from the aorta, between the pillars of the diaphragm.

Usually and in fact almost always, when its trunk is not exceedingly short, it gives off first, from its upper side, the superior diaphragmatic arteries (A. diaphragmatic ce, s. phrenic œ majores, s. principes, s. inferiores ), which arise sometimes separately and sometimes by a very short common trunk. Sometimes one of these arteries comes from the aorta and the other from the cœliac artery ; more rarely one or both of them are given off by one of the branches of the cœliac, or even by the renal, or finally by the inferior capsular artery. They ascend directly on the pillars of the diaphragm, to which they give off branches, and also supply the middle capsular arteries {A. suprarénales medial), which go to the renal capsules ; and when they have arrived at the upper extremity of the pillars, divide into an anterior and a posterior branch.

The posterior branch, which is the smaller, is sometimes, at least On one side, given off wholly or partially by the aorta. Even when the principal trunk arises from the cœliac artery, it sends considerable branches to the renal capsules ; these are called the superior capsular arteries (A. suprarenales superiores ). It then goes outward, below and behind the tendinous centre of the diaphragm, to be distributed principally in the lumbar portion of this muscle.

The anterior branch is much larger, and must be considered as the continuation of the trunk ; it goes forward, along the esophagceal opening, before which it divides into two branches, an anterior and internal, and transverse which is much smaller, and is distributed to the central portion of the diaphragm, and anastomoses with that of the opposite side, while the external is much larger, goes outward, and gives ramuscules to most of the costal portion of the diaphragm.

(1) Monro is mistaken in saying that these arteries arise from the aorta (vol. iii. p. 333). Mayer (p. 656) also seems to think this is the most common arrangement. Murray (p. 61) and Sœmmcrring (p. 252) think that they arise from the aorta asfrequently as from the cœliac artery. Bichat is more correct (p. 283) in saying that they arise from the cœliac artery more frequently than from the aorta. This remark was made long before him by Haller (part 2, notes to vol. i. p. 6).

(2) A. F. Walther, De arteriis eœliuci Leipsic, 1729.

The inferior diaphragmatic arteries go principally to the lower face of the central portion of the diaphragm. They communicate with the external which arise from the internal mammary, with the inferior intercostal, and the lumbar arteries ; also pass through the diaphragm, enter the chest, and give off, in this cavity, the pericardiac and the inferior mediastinal arteries.

§ 1446. The cœliac trunk after and sometimes also before giving off the inferior diaphragmatic arteries divides most generally into three branches ; these are the coronary arteries of the stomach, the hepatic and the splenic artery. These three branches form the tripus Halleri.

§ 1447. The coronary artery of the stomach, Stomogastrique, Ch. (A. coronaria ventriculi , s. gastrica superior, major sinistra, gastrohepatica sinistra), is usually much smaller than the other two branches of the cœliac artery. Sometimes, but rarely, it arises from the aorta before the latter, either alone or by a trunk which is common with it, sometimes with only one of the inferior diaphragmatic arteries, particularly that of the left side, and sometimes with both.

It proceeds first upward and forward, then to the left, and gives off,

1st. Several inferior esophagœal arteries (A. esophagece inferiores) .

2d. Several posterior cardiac arteries {A. cardiacce posteriores ), which are distributed around the superior orifice and on the large curvature of the stomach, and descend principally on its posterior face.

3d. Very frequently, and even almost always, the left hepatic artery.(l)

The anterior and superior gastric and the other inferior esophagœal arteries, arise from this artery or from the following branch.

4th. The gastric branch (R. gastricus). When the coronary artery of the stomach gives off the left hepatic artery, it bifurcates to give origin to it and also to the gastric branch. The latter usually divides into several large anterior and posterior ramuscules, which are distributed on the anterior and posterior faces of the stomach, and anastomose with each other and with the preceding. It always gives off a greater or less anastomosing branch, which follows the small curve of the stomach, and goes toward the right side, where it anastomoses with the pjdoric artery.

§ 1448. The hepatic artery (A. hepatica) is larger than the preceding. Sometimes it does not give off the usual number of branches. The anomaly may then occur in several different ways. In fact the hepatic artery is sometimes divided into two trunks, which arise one from the cœliac artery as usual, the other from the coronary artery of the stomach, or from the superior mesenteric artery, or more rarely from the aorta ; sometimes there are three trunks, one of which arises from the cceliac, a second from the superior mesenteric artery, a third from the aorta.

(1) Hence the term g astro-hepatic which has been applied to it. In this case the coronary artery of the stomach is not, as generally, much smaller than the other two branches of the cœliac artery, but it is often as largo as the hepatic, especially when it gives off at the same time one or both of the inferior diaphragmatic arteries.

Sometimes but more rarely the hepatic artery arises entirely from the aorta. The rarest anomaly is that where it comes entirely from the superior mesenteric artery.(l)

The trunk of the hepatic artery proceeds transversely to the right side ; it then goes a little obliquely forward and upward, entering into the transverse fissure of the liver.

Just before arriving at the liver it divides into two branches, the right gastro-epiploic artery and the hepatic branch.

§ 1449. The right gastro-epiploic artery (Jl. gastrica dextra inferior , coronaria ventriculi dextra inferior , gastro-epiploica dextra. pancreatico-duodenalis), which is much smaller when only one hepatic trunk exists, but which in other cases is as large as the hepatic branch, goes downward, and to the left, toward the origin of the duodenum, passes below this intestine, between it, the pylorus, and the pancreas, reaches the great curvature of the stomach, proceeds along it from right to left, and anastomoses with the left inferior gastro-epiploic artery.

In its course it gives off the following branches :

1st. Before arriving at the duodenum and passing under this intestine, one or two considerable branches, the pancrealico-duodenal arteries (A. pancreatico-duodenales), which descend along the concavity of the duodenum, give to it numerous ramuscules, and also give origin to one or two retrograde pyloric arteries (A. pyloricce inferiores) ; the latter, which are distributed around the pylorus, give off other considerable branches to the head and to the right portion of the pancreas, and anastomose extensively with the branches of the superior mesenteric artery.

One or more of these anastomosing branches are sometimes so large that we might consider the right gastro-epiploic artery rather as a branch of the inferior mesenteric than as arising from the cœliac artery.

2d. The continuation of the trunk proceeds along the large curvature of the stomach, gives a great number of ascending branches to the two thirds on the right of this viscus, and sends others, which are less numerous and which descend between the two layers of the large epiploon, where they form the right and middle epiploic arteries (A. epiploicæ dextrœ et inediœ). These branches anastomose with each other and with those of the left gastro-epiploic artery by large arches.

Near the commencement of the left third of the stomach the trunk of the right gastro-epiploic artery gradually diminishes and becomes very small, so that we can easily perceive the limit which separates it from the left gastro-epiploic artery, with which it anastomoses in this place.

(1) Haller, Ic. anat., part viii. p. 36.

§ 1450. From the hepatic branch ( R . hepaticus ), sometimes also from the trunk of the hepatic artery, before it gives off the right gastroepiploic artery, arises a smaller branch, called the superior pyloric artery ( A . gaslrica dextra superior , coronaria ventriculi dextra superior , pylorica superior). This branch descends towards the pylorus and anastomoses with the inferior pyloric, and with the branches of the left gastro-epiploic by small arches.

Soon after the hepatic branch divides into a right and left.

The right hepatic artery (A. hepatica dextra) is larger than the left. It is distributed to the right lobe of the liver and to the gall-bladder.

This soon divides into two branches ; the smaller goes to the middle part of the liver {A. hepatica dextra minor, A. hepatica media ) ; this sometimes arises directly from the aorta, although the origins of all the other branches are normal ; the other is greater and is the continuation of the trunk. The latter goes to the vena-porta, enters the transverse fissure of the liver, where it divides into numerous ramifications, anti almost always gives off, just before entering, one or two cystic arteries (A. cystica).

The right hepatic artery, either alone or with the right gastro-epiploic artery, not unfrequently arises from the superior mesenteric artery, an arrangement always indicated by the large anastomoses between these two arteries by means of the pancreatico-duodenal arteries. The left hepatic artery, not unfrequently, is separated from the right, and arises from the tripus Halleri by a common trunk with the coronary artery of the stomach.

§ 1451. The splenic artery (A. splenica, s. lienalis ) is the largest of the three branches of the cceliac artery in the adult, and goes to the left soon after arising, proceeding below and behind the stomach in the transverse fissure of the pancreas.

In this course it gives off,

1st. From its lower side the middle and the left pancreatic arteries (A. pancreaticœ media et sinistra), which vessels are usually large and arranged in an arch ; they go from right to left on the pancreas, and from their convexity arise numerous anterior and posterior branches which penetrate from below upward into the pancreas.

2d. More to the left, five or six short gastric arteries arise (A. gastrica breves, s. fundi ventriculi). These almost always make a part of the numerous branches into winch the trunk of the splenic artery divides before entering the spleen.

These vessels retrograde toward the left large extremity of the stomach and communicate on its two faces, by numerous anastomoses, with the coronary and right gastro-epiploic arteries.

We observe a lower branch, which is large ; this is the left, gastroepiploic artery (A. gaslrica , s. coronaria sinistra inferior , gastro-epiploica sinistra) ; this descends along the great curvature of the stomach, usually anastomoses very evidently with the right gastro-epiploic artery, and gives off large branches, the left epiploic arteries, to the large epiploon.

II. SUPERIOR MESENTERIC ARTERY.

§ 1452. The superior mesenteric artery {Jl. mesaraica , s. mesenterica superior ) is generally a little and often considerably larger than the cœliac artery, when the latter arises partly from the aorta or from the superior mesenteric artery, and generally comes from the trunk of the aorta directly below the cœliac trunk. It not unfrequently arises with it by a common trunk, which is sometimes nearly an inch long,(l) — a curious arrangement, as it resembles the formation of the tortoise.

The artery is covered first by the pancreas, and descends perpendicularly behind it on the lower part of the duodenum. It passes between the two layers of the mesentery and near its centre describes a considerable curve, the convexity of which looks forward and downward to the left while its concavity is turned to the right backward and upward. The centre and upper part of this curve is much farther from the small intestine than its lower portion ; it gradually diminishes and terminates on the right and downward in the right lumbar region.

All the constant branches of the superior mesenteric artery arise from this curve, which furnishes blood to a part of the pancreas, to all the small and most of the large intestine, especially to its right and transverse portions. The first branches go to the pancreas and to the duodenum ; the next go to the large intestine ; and the inferior to the small intestine. The first ansstomose with the hepatic artery, more rarely also with the coronary artery of the stomach. (2)

The arteries of the small intestine {Jl. intestinales ), which come from the convexity of the curve of the superior mesenteric artery, deserve to be mentioned before the others, (3) because the first of them arises higher than those which come from the concavity, and the study of the latter naturally leads to that of the branches which come from the inferior mesenteric artery.

The superior intestinal arteries are usually the longest ; the first is however a little shorter than the following, but the last or the lowest are shorter than the others and also the smallest.

We generally number from sixteen to twenty ; but we must reduce this number to ten or eleven, as it is more correct to consider the lowest, not as distinct trunks, but as secondary branches of the last branch, which in going from left to right and from below upward anastomoses with the last of the branches which arise from the concavity.

(1) Haller considers this arrangement as a rare anomaly, because he has observed it only once; ( Ic . anat ., part viii. p. 35, No. 11). We however think it more common, for we have seen it five times, although we did not look for it particularly in the cadavers we examined.

(2) Barclay, loc. cit., p. 182.

(3) This method has been followed correctly by Mayer ( Ang ., p. 170), and Monro ( Outlines , p. 335); but not by Murray (p. 68), Scemmerring (p. 267), and Bichat (p. 267).

If we follow the usual method, the intestinal arteries are almost always more than twenty in number, and the last eight or nine are extremely small and short.

These arteries dimmish from above downward in respect to their diameter ; we however find among the largest some which are very small, although they also arise from the trunk of the mesenteric artery.

They all proceed between the two folds, of the mesentery to the intestine, distributing in their progress numerous branches to this membrane and also to the mesenteric glands. They usually divide into an upper and a lower branch. This division occurs sooner or later, in proportion as the branches are shorter or longer. These branches anastomose with the opposite branches of the adjacent arteries and form a large arch, composed of as many smaller arches as there are intestinal arteries ; the convexity of this arch always looks toward the concavity of the small intestine. The two branches do not suddenly unite, but anastomose at a proportionally short distance from the intestinal canal.

Numerous secondary ramifications arise from the convexity of these arches ; these are very compactly situated and very frequently anastomose. Hence results a much more extensive external arch, composed of a still greater number of small arches, whence arise numerous ternary branches. These also bifurcate two or three times, and anastomose in the same manner, at least where the intestinal arteries are larger.

These vessels represent by their division a very coarse net.

Finally, from the external surface of this net arise numerous arterioles, which are divided into an anterior and a posterior series, which go to the intestinal canal and are distributed on its internal membrane after still more subdivisions and anastomoses.

A minute description of their distribution in the intestine will be given after that of the intestinal canal more properly than in this place.

§ 1453. From the concavity of the curve of the superior mesenteric artery, nearly opposite the place where the third, fourth, fifth, and sixth intestinal arteries arise, and about an inch from each other, are constantly given off at least two, and almost as often or at least not very unfrequently three branches, which belong exclusively to the colon, particularly to its right portion; these may be called the right colic arteries { Jl. colicæ dextrœ). Of these branches the centre is usually smaller than the other two, and generally it arises nearer the superior.

§ 1454. The lowest, which goes to the right outward and downward, is called the inferior right colic or the ilco-colic artery {Jl. colica inferior dextra , ileo-colica). Some distance from its origin it sends downward a branch, which anastomoses with that which we have considered as the last intestinal artery and which is generally regarded as the trunk of the superior mesenteric artery, uniting with this artery a little before it terminates, partly also proceeds as the artery of the cœcal appendix ( A.appendicalis ) to the vermiform appendage of the cæcum, along which it reascends to its extremity, giving off from its convexity a great number of branches, which arise at acute angles.

Jt afterwards immediately divides into an ascending and a descending branch.

The descending branch, the cœcal artery (Jl. cœcalis), sends a large anastomosing ramuscule to the last intestinal artery or to the extremity of the curve of the superior mesenteric artery, and afterwards divides into two other secondary branches, the anterior and the posterior cœcal artery, which are distributed in the corresponding parts of the cæcum and anastomose with the artery of the cœcal appendix.

The ascending or anastomosing branch (R. ascendens , s. anaslomoticus) ascends at a short distance from the concave part of the intestinal canal along the ascending colon, to which it gives off numerous branches, not however equal in number to those of the intestinal arteries, which also anastomose less frequently. These branches divide near the colon into minuscules, forming an anterior and a posterior series, all of which are distributed to the parietes of this intestine.

§ 1455. The middle right colic artery {Jl. colica dextra media, colica, dextra , colica dextra inferior ) is always the smallest of the three branches which arise from the concavity of the curve of the mesenteric artery, and often comes from the superior. Sometimes but very rarely it is given off by the inferior right colic artery.(l) It usually commences very near the superior colic artery.

When it. is given off by the latter, it generally arises at the place where it anastomoses, when it comes from the mesenteric artery, with the superior colic artery by a short but very large branch ; so that when it forms a distinct trunk we should consider it as an anastomosing branch between the superior right colic artery and the trunk of the superior mesenteric artery.

When it is a branch of the superior mesenteric artery, it divides some" distance from its origin into a superior and an inferior branch.

The superior ascending branch is much shorter and anastomoses with a similar branch from the superior right colic artery.

The inferior descending branch is much larger, goes along the concavity of the ascending colon, and anastomoses by a large arch with the ascending branch of the inferior right colic artery.

This artery supplies the middle part of the ascending colon with blood.

§ 1456. The superior right colic artery {Jl. colica superior dextra , colica media, s. anastomotica dextra ) generally arises some inches below the origin of the trunk and as high as the transverse vnesn-colon. It afterward enters between the two layers of the peritoneum, goes directly forward toward the centre of the transverse colon, and divides into a right and a left branch.

(1) Bichat seems to doubt this fact, but wrongly. He says that the inferior colic artery is constantly distinct. Murray and Mayer do not mention it, although they very correctly state that the two superior right colic arteries not unfrcquently form one trunk. Sabatier and Sœmmerring are more correct in saying that the two inferior right colic arteries rarely arise together. Others, as Portal and Monro, mention only the cases where the three arteries form three distinct trunks.

The right branch is generally a little smaller than the other, is also shorter, and anastomoses with the ascending branch of the middle right colic artery, which it sometimes replaces entirely (§ 1455).

The left branch ( R . anastomolicus magnus) passes behind the left and largest portion of the transverse colon, communicates with the ascending branch of the left colic artery given off by the inferior mesenteric artery, and forms with it the largest anastomosis found in the adult. This anastomosis is seldom deficient.

This artery is distributed to the upper part of the ascending, and to the central and right portions of the transverse colon.

§ 1457. One branch of the superior mesenteric artery, which exists only in the early periods of life, is the omphalo-mesenteric artery (A. omphalo-mesaraica ), which generally arises from this trunk, but in no determinate place ; this artery, accompanied by the veins of the same name, leaves the mesentery, passes on the lower part of the small intestine, arrives at the umbilicus, comes from the abdomen with the intestine, enters into the umbilical sheath before the end of the second month of pregnancy, and extends to the umbilical vesicle, and distributes its ramifications on its surface. This branch constantly exists until the end of the second month, after which it is almost always obliterated and is visible only in the mesentery and near the umbilicus. Sometimes it continues, always preserving rather a large caliber, and extends with its accompanying vein to the umbilical ring or even into the cord. Sometimes it is obliterated, but extends from the intestine to the umbilicus. These two cases occur principally when the intestinal canal, either alone or with other organs, is arrested at one of the first degrees through which it passes successively in its formation. The omphalo-mesenteric artery is undoubtedly the largest of those in the fetus.

in. INFERIOR MESENTERIC ARTERY.

§ 1458. The inferior mesenteric artery {-A. mesaraica, s. mesenterica inferior ) comes from the aorta, generally some inches lower than the preceding, and usually about an inch above the bifurcation of the trunk of the aorta where the two primitive iliac arteries arise.

The only exceptions are when several renal arteries existing, one of them arises very low and the mesenteric artery is constantly given off from the aorta above the latter ; its description however should precede theirs, because it. comes from the anterior part of the trunk of the aorta, and because it is distributed to the intestinal canal, as are all the other arteries which arise in like manner from the anterior side of the abdominal aorta.

Still more rarely it comes from the primitive iliac artery,(l) which happens when the aorta bifurcates higher than usual.

It is always a little smaller than the renal arteries, proceeds obliquely to the left and upward under the peritoneum, penetrates immediately between the layers of the iliac meso-colon, and divides into several branches, which belong only to the left portion of the colon and to the rectum, the upper of which may be called the left colic arteries (A. colictz sinislrœ), to distinguish them from the right (§ 1456) which arise from the superior mesenteric artery, while the lower go to the rectum and are called the upper hemorrhoidal arteries (A. hcmorrhoideœ superior es).

This artery is rarely deficient(2), a remarkable anomaly, which resembles the normal formation of many animals, viz. birds and reptiles, in which the posterior mesenteric artery gradually diminishes and entirely disappears.

§ 1459. The left colic arteries (A. coliccc. sinislrœ) arise from the upper convex part of the inferior mesenteric artery. We sometimes find two or three, a superior, middle, and an inferior. The middle is sometimes blended with the superior and sometimes with the inferior. The first case is more common.

The superior left colic artery (A. colica sinistra superior, anaslomotica sinistra ), generally the larger, proceeds along the descending colon and divides into two branches. This division occurs sometimes immediately, when it gives off the middle colic artery, sometimes later, when this arises separately from the mesenteric artery or by a common trunk with the inferior.

In the second case one branch goes to the right, the other to the left side. The latter anastomoses with the left branch of the superior right mesenteric artery, behind the left portion of the transverse colon, and thus forms a large arch ( arcus anastomolicus magnus ), (§ 1456) to produce which however it but slightly contributes. This anastomoses, in front of the upper part of the descending colon, with the ascending branch of the middle left colic artery.

The middle left colic artery (A. colica sinistra media) sometimes forms the lower branch of the preceding ; and then arises from it very early, but more frequently is a distinct trunk, which soon after divides into two branches, the larger of which ascends along the left colon, and anastomoses with the descending branch of the superior left colic artery ; and the inferior communicates with the ascending branch of the inferior left colic artery.

The inferior left colic artery (A. colica sinistra inferior), which is distributed to the lower part of the descending colon, divides still sooner into two branches, which anastomose, the ascending with the descending branch of the middle left colic artery, and the descending with the ascending branch of the superior hemorrhoidal artery.

(1) Petsclie, Sylt, obs.; in Haller, Coll.diss., vol. vi. p. 761.

(2) Fleischmann, Leichenöffnungen, 1815, p. 239.

§ 1460. The superior hemorrhoidal artery {A. hemorrhoidea superior, s. interna ) arises from the concavity of the curve described by the inferior mesenteric artery. It would then be more correct to consider it as the inferior of the two branches, into which this artery often divides, and the upper of which furnishes the left colic arteries.

It goes to the right, and descends behind the rectum, distributing its branches to most of this intestine. It usually divides into two branches, the upper of which is smaller, and the lower larger, and is the continuation of the trunk. Each branch immediately divides, although at some distance from the rectum, into a right and left, which open together downward and beside each other by considerable anastomoses, and are distributed to the rectum, where their branches usually communicate with those of the vesical and uterine arteries.

We shall mention the difference in the arrangement of the arteries of the small, and those of the large, intestine, when treating of the intestinal canal.

II. LATERAL BRANCHES.

§ 1461. The lateral branches of the abdominal aorta are the middle capsular, the renal , and the spermatic arteries.

I. MIDDLE CAPSULAR ARTERIES.

§ 1462. The middle capsular arteries (A. capsulares mediae) are one, two, and sometimes even three, in number, and arise from the aorta very near each other, usually above, sometimes below, and a little in front of the renal arteries. In some subjects they come from the cceliac or from the renal arteries. They go to the right and left, passing on the bodies of the vertebra, and arrive from below upward on the posterior face of the renal capsules, but at the same time they send branches to the pillars of the diaphragm, and to the lymphatic glands in the lumbar region.

II. RENAL ARTERIES.

§ 1463. The renal or emulgent arteries (./2. renales s. emulgenles) come entirely from the side of the aorta, directly below the superior mesenteric artery. They arise at a right or at an almost right angle ; they proceed from before backward and from within outward, directly on the lateral faces of the bodies of the first or second lumbar vertebra, and, arrived at the kidney, penetrate into its fissure after dividing, most frequently near this organ, into several and generally into three branches, which also subdivide before entering its substance.

They arise almost opposite each other ; the right however is a little lower than the left, because the kidney of this side is lower than that of the other. To this law however there are exceptions. We remark particularly that when the right renal artery is double, the superior usually arises a little higher than the single renal artery of the left side.

These arteries are very large, but not, as Bichat says, the largest in the abdomen, since they are smaller than the cceliac or the superior mesenteric artery.

§ 1464. The renal arteries present many anomalies. The most usual afFecl their number. We generally find only one renal artery on each side. This number however is frequently, in fact often, increased by reducing the branches into distinct trunks, which arise directly from the aorta. The transition to this arrangement is marked by that where the single renal artery early divides into branches : this early division is not unfrequent, and often occurs only on one side ; the renal artery of the opposite side being already divided into several separate trunks.

This anomaly of the renal arteries differs,

1st. In the conditions of its occurrence; 2d, in the number of divisions it produces ; 3d, in its occurrence on one or both sides ; 4th, in its being more frequent on one side than on the other ; 5th, in the proportional size of the separate trunks ; 6th, in their place of origin ; 7th, in their insertion ; 8th, in their relation with the renal veins.

1st. The conditions in which the number of the renal arteries is increased are,

a. An unusual size of the kidneys.

b. Their unusual length, although their size is not much increased. In this case their central portion is often strangulated.

c. The union of the two kidneys.

d. Their unusually low situation in the pelvis.

2d. In respect to number. The renal arteries are increased by one more commonly than by many.

Sometimes however there are three, four, and even five on one side.

3d. In regard to the simultaneous existence of several renal arteries on both sides at once, we remark generally that when there are not more than two, the anomaly occurs on one side as frequently as on both. When however this increase is more than two, it is rarely confined to a single side, although it very seldom occurs on both sides in the same degree. This rule however is not general, since four renal arteries sometimes exist on one side and only one on the other.

4th. The anomaly does not seem to affect one side of the body more than the other. This remark is the result of our own observations ; it however is confirmed by the difference in the assertion of authors on this subject. Some say that the anomaly is more frequent on the left and others on the right side.

5th. The anomaly is the least possible when one of the two renal arteries is much smaller than the other. The larger then is generally but not always the upper; it forms the normal trunk. In fact the supernumerary renal arteries not infrequéntly have the same caliber, each of them, considered separately, being a little smaller than the normal artery, except when one kidney is larger than the other.

6th. The supernumerary renal arteries also vary much in their origins. The nearest to the normal formation is where the second renal artery arises directly at the side of the normal artery ; but they are frequently very distant from each other, so that one or some of them not only arise from the aorta, below the inferior mesenteric artery, but also come from the primitive iliac or even from the hypogastric artery ; the last two cases however usually occur only when the kidneys are blended together or are situated very low. But if we except those cases where the kidney is situated very low, one renal artery generally arises from the usual place, however remote may be the origin of the others.

When more than two renal arteries exist, one generally arises very far from the rest. Sometimes they are situated at equal distances from each other. Sometimes also when four occur two of them arise very high, and two very low.

7th. The place of insertion is more abnormal, the lower the origin of the renal arteries, and the greater the anomaly in the form and situation of the kidneys. If the arteries are given off very low, although the situation of the kidneys is normal, they frequently do not enter its fissure, but are inserted at its lower extremity. If the kidney is situated very low, the vessels usually converge fiom all sides to enter it.

8th. The relation between the renal arteries on one side, and the emulgent veins and the vena-cava on the other, may be regarded in two points of view :

1st. In regard to their simultaneousness and frequency. A series of careful observations permit us to establish as a principle that the veins divide much more rarely than the arteries, and consequently the veins are not always abnormal, in this respect, when the arteries are, although this is somewhat common, even when the arteries exist, in regard to these two orders of vessels at the same time ; the number of renal arteries nevertheless frequently exceeds that of the emulgent veins, although sometimes, but rarely, the veins alone are abnormal.

2d. Usually, particularly when more than two renal arteries exist, the relation of the situation with the veins is changed in this respect, that one or both of them pass before and not behind the vena-cava inferior to go to the kidney. One easily perceives that this rule can apply only to the renal arteries of the right side.

The two renal arteries much more rarely arise from the anterior face of the aorta by a common trunk which, in the only case of this anomaly known to us, was inserted very near the mesenteric artery.

Other anomalies relate to the side of the vascular system whence the renal vessels arise. Each renal artèry generally goes to the kidney of the same side. The only exception to this rule is when the kidneys exist in the pelvis ; one of the renal arteries then not infrequently arises from the primitive iliac, or from the hypogastric artery of the opposite side.

§ 1465. Beside these slight and inconstant differences between the renal arteries of the two sides, in respect to the height at which they arise, they are constantly distinguished from each other by their length ; that of the right side being longer than the other, and more so because the aorta is situated more to the left. In its course to the kidneys it usually passes behind, but not unfrequently before the ascending vena-cava.

The renal arteries belong particularly to the kidneys and enter almost wholly into the fissure. Proceeding however they always give several greater or less branches. These are,

1st. The inferior capsular artery (./?. suprarenalis inferior) almost constantly arises from the renal artery, or at least comes very rarely from the aorta itself with the middle capsular arteries. This artery is even sometimes double, since, beside the usual artery, that which directly arises from the origin of the renal artery, a smaller one exists, which comes from one of its branches.

This inferior capsular artery is not unfrequently very large. In this case it gives off branches to the lumbar portion of the diaphragm, and sometimes the whole inferior diaphragmatic artery comes from it.

2d. The branches which go to the pelves of the kidneys and to the ureters.

3d. Rarely, and most generally on the left, and even then usually only where several renal arteries exist, the spermatic artery, which in this case constantly arises from the inferior renal artery. We have however satisfied ourselves that when the renal artery divides into several branches, the spermatic artery is by no means always inserted in one of the latter.

4th. Some branches to the renal capsule. These ramifications enter into the substance of the kidney, and there are likewise some small branches which go from the substance of the kidney to the capsule.

5th. More rarely the right renal artery sends a branch to the lower part of the liver.

HI. SPERMATIC ARTERIES.

§ 1466. The spermatic arteries (.4. séminales, s. sp er malic ce) are usually single but not unfrequently double. They generally arise a little but sometimes far above the renal artery. They rarely originate opposite each other ; one is frequently detached much higher than the other and much more before it, and most generally before the middle capsular arteries, making with the aorta an acute angle. Frequently also the spermatic artery on one side (§ 1464) arises from the renal, or from the inferior or middle capsular artery. More rarely it arises from the lumbar, from the external iliac, from the hypogastric, or even from the epigastric artery of its side. It generally extends vertically downward, but sometimes also it turns on the renal vessels before assuming its downward and outward direction, which it follows and keeps it directly behind the peritoneum, and before the ureter, which it crosses. That of the right side also passes before the vena cava inferior.

The spermatic artery is much shorter in the female than in the male, since it does not leave the abdomen, and is distributed to the ovaries, and also to the. Fallopian tubes, to the round ligaments, and to the upper part of the uterus, communicating with the. uterine arteries by numerous anastomoses.

In the male on the contrary it leaves the abdomen through the inguinal ring, forms with its corresponding vein and the lower part of the vas deferens the spermatic cord, gives branches to the common membrane of the cord and testicle, and is distributed principally in the latter organ.

In its course it gives upward branches to the duodenum, the liver, the transverse meso-colon, the renal capsules, the lymphatic glands in the lumbar region, and to the ureter, and frequently anastomoses with the branches of the mesenteric and lumbar arteries.

III. POSTERIOR BRANCHES. LUMBAR ARTERIES.

§ 1467. The lumbar arteries (A. lumbales ) are the posterior rather than the lateral branches of the abdominal aorta, since they usually arise nearer the centre of the posterior face than the sides of this artery. In this respect there are different degrees between the entire lateral insertion of these arteries and the origin of those which correspond on the right and on the left by a common median trunk often several lines in length, before dividing into the right and left lumbar arteries.(l) All the lumbar arteries of the same subject are arranged in this respect after the same type.

These arteries correspond to the intercostal arteries and are also formed on the same level as they, both generally and particularly. But they are usually larger. Soon after arising, they go outward in the groove of the vertebrae, between the fasciculi of the psoas magnus muscle, to which they give numerous branches, as also to the quadratus lumborum and lumbar vertebrae, gradually arrive at the transverse processes of the latter, and always divide at their base, opposite the intervertebral foramina, into a posterior or dorsal and an anterior or lumbar branch.

(1) Scemmerring (p. 277), who follows Murray (p. 75) in this, does not mention that the right and left lumbar arteries arise by a common trunk, but speaks only of the fourth. Others, as Mayer, Boyer, Sabatier, Hildebrandt, and Monro, do not speak of it at all. Portal is more correct when he states in a general manner that the synonymous lumbar arteries of the two sides sometimes arise by a common trunk. We have found that this anomaly is not unfrequent, and that, as we have already remarked, it usually affects all the lumbar arteries. Its frequency, compared with the proportional rarity of a similar arrangement in the intercostal arteries, is worthy of remark, as it coincides with the less marked development of the abdominal parietes.

The 'posterior or dorsal branch (II. dorsalis ) is usually the smaller, and gives off a branch called the spinal lumbar artery (Jl. spinalis lumbalis ), which passes into the spinal canal through the intervertebral foramen, is distributed on the dura-mater and the pia-mater, descends to the cauda equina, anastomoses with the synonymous branch of the opposite side and also with the anterior spinal artery, and is distributed also to the lower part of the muscles of the back.

The anterior or lumbar branch ( R. lumbaris ) -goes forward between the broad abdominal muscles, within which it anastomoses with the branches of the epigastric artery.

There are usually as many lumbar arteries as there are lumbar vertebrae, viz. live. In general however there are not five which arise by separate trunks, but many of them, especially the two or three lower ones, often arise by a common trunk, which soon bifurcates. Sometimes this union of the two lumbar arteries on the same side, situated one above the other, coincides with that of the synonymous branches on the right and left, on one or on both sides, which we have already mentioned.

Most generally even only the four superior lumbar arteries arise from the aorta, and the fifth is given off by the anterior branch of the fourth.

Thus we usually observe at most but four aortic lumbar arteries.(l)

Finally, there is no symmetry in this respect between the lumbar arteries of the two sides of the body.

§ 1468. The first lumbar artery is frequently deficient, and in most subjects it arises from a trunk in common with the last intercostal artery or it is replaced by .the branches of the latter. It is always small, so that when this arrangement exists and while at the same time the inferior lumbar artery arises by a secondary branch, which is much more common, we observe only three of these arteries.

Even when it is separated from the last intercostal artery, it proceeds a short distance below the lower edge of the last rib, under the insertion of the diaphragm. Sometimes its anterior branch curves between the transversalis abdominis muscle and the peritoneum along which it descends.

The second lumbar artery usually arises between the second and the third lumbar vertebra ; it goes first a little from below upward, then from before backward, and from within outward in the groove of the second vertebra. Its anterior branch is distributed principally in the quadratus lumborum and transversalis abdominis muscle.

The third lumbar artery arises between the third and fourth lumbar vertebrae, and descends on the first of these two bones. Its anterior branch is very large and passes between the psoas magnus and the quadra tu s lumborum muscles, to which it gives branches, descends toward the anterior part of the crest of the ilium, and directly above this place goes through the abdominal muscles to the glutæi, where it ramifies and anastomoses with the gluteal artery.

(1) This assertion cannot be disputed, when we speak of the trunks which arise directly from the aorta. Boyer (p. 127) and Portal (p. 290) have adopted it. But it is very incorrect to consider, with Haller and Sabatier, the inferior intercostal as the first lumbar artery, and consequently to admit six lumbar arteries, although the first lumbar not unfrequently arises from the last intercostal artery, or is replaced by its branches.

The fourth lumbar artery arises on the fourth lumbar vertebra, or between the fourth and the fifth: Its anterior branch passes before the

quadratus lumborum muscle, proceeds forward on the crest of the ilium, through the muscles of the back, to enter, like the preceding, into the glutæi muscles.

The fifth lumbar artery is a branch of the sacral artery ; we shall therefore describe it when speaking of the latter.

Chapter V. Arteries of the Pelvis and the Lower Extremities

§ 1469. The aorta usually divides on the fourth lumbar vertebra, or between the fourth and fifth, into two or three trunks. Two are much larger and more constant, and are the arteries of the lower extremities (J3. crurales , Barclay) being called at their origin the primitive iliac arteries ; they separate from each other at an acute angle and go outward. The third trunk is much smaller and inconstant, and is called the middle sacral artery.

I. MIDDLE SACRAL ARTERY.

§ 1470. The middle sacral artery (A. sacra , s. sacralis media), although very small, being no larger than a lumbar artery, is very remarkable, first, because from its situation and distribution it in fact represents the continuation and the end of the trunk of the aorta ; secondly, because it adds to the analogy already existing between the distribution of the upper end and that of the lower part of the aorta.

When it arises from the aorta, it comes from its posterior side, directly above the origin of the two primitive iliac arteries. It is not unfrequently given off by the latter, especially that of the left side, from which it generally then arises very high, directly below its origin.

It descends more or less exactly on the centre of the anterior face of the body of the last lumbar vertebra, and of those of all the false vertebrae of the sacrum and coccyx, directly upon the surface of these bones, and curves frequently.

It gives off only lateral branches.

The first and largest is usually the fifth or the last left lumbar artery (§ 1469), which is sometimes larger than the continuation of the trunk, and then the middle sacral artery seems to arise from the inferior lumbar artery.

This branch, like all the lumbar arteries, goes backward and outward. It divides, before the intervertebral foramen, between the fifth lumbar vertebra and the first false vertebra of the sacrum, into two branches, a posterior or dorsal , and an anterior , which is much larger. The first is distributed as usual ; it goes outward, under the psoas magnus muscle, and sometimes, when the fourth lumbar artery does not descend so low as usual, it proceeds on the crest of the ilium, and goes to the quadratus lumborum muscle, through which it passes into the broad abdominal, and also into the glutæi muscles ; sometimes when these branches arise from the fourth lumbar artery, and the ilio lumbar artery is not as much developed, it penetrates into the psoas magnus and the iliacus muscles.

Two transverse branches more or less tortuous than usually arise from the lateral parts of the middle sacral artery on each false vertebra of the sacrum ; these go outward, give numerous ramifications to the periosteum and to the substance of the sacrum, anastomose with the branches of the lateral sacral arteries which go to meet them, penetrate with them into the spinal canal, through the anterior sacral foramina, then emerge from the posterior sacral foramina, and are expanded in the inferior part of the multifidus spinæ muscle.

The middle sacral artery finally terminates at the end of the coccyx, in the lower extremity of the rectum and in the fat which surrounds this intestine.

This artery is not always single ; it sometimes divides into two branches, which anastomose with each other and with the lateral sacral arteries.

There is constantly an inverse relation between the middle and the lateral sacral arteries in respect to their development, when one or the other is unusually large.

II. PRIMITIVE ILIAC ARTERIES.

§ 1471. The primitive iliac arteries (A. iliac ce. primitives, s. communes , s. pelvi-crurales , s. crurales lumbales, s. cruri-lumbares ) separate at an acute angle, go outward, downward, and forward, on the last two lumbar vertebræ, and on the first false vertebra of the sacrum, the right after passing on the left primitive iliac vein, the left proceeding directly before and at the same time on the outside of the synonymous vein, and divide as high as the sacro-iliac symphyses, into two considerable trunks, the hijpogastric and the external iliac artery.

The primitive iliac arteries usually have about the same .length and caliber on both sides. The right however is most generally a little higher than the left, because the aorta occupies the left side of the vertebral column as the primitive iliac arteries, nevertheless, both arise at the same height. The left descends a little more vertically than the right. Those authors who mention some difference between the two primitive iliac arteries, especially Mayer, and after him Sœmmerring, indicate only this relation, which in fact is most frequently observed. These anatomists also assert that the right primitive iliac artery is a little smaller than the left.

We have never observed this last difference, but rather the contrary. The first in fact generally occurs, although we have sometimes but very rarely remarked an inverse arrangement, and even in a much more evident manner, although the aorta ascend as usual on the left of the vertebral column.

In one case of this kind now before us the right primitive iliac artery is nearly a third shorter than the left, and bifurcates between the fourth and fifth lumbar vertebræ.

The most usual arrangement is remarkable, because it adds still more to the analogy between the upper and lower halves of the body, since the greater length of the right primitive iliac artery resembles the innominata of the right side, arid that of the left side the origins of the left carotid and subclavian arteries by two distinct trunks. The latter arrangement however is only indicated at the lower extremity of the aorta, where a perfect repetition has not yet been found, at least to our knowledge.

The rarest arrangement corresponds to the inversion of the right and left trunks of the arch of the aorta, which has been sometimes observed, although the aorta presented no other anomalies.

The primitive iliac arteries usually give off in their course small branches, which go to the psoas and the iliacus muscles, the ureters, the vena-cava, and the lymphatic glands of this region. They rarely give off a part or the whole of the ileo lumbar artery, and still more rarely they supply a renal or a spermatic artery.

1. I. Hypogastric Artery

§ 1472. The hypogastric artery (A. hypogastrica s. iliaca interna, s. posterior pelvica, s. hypoiliaca) descends a little forward and inward, soon penetrates, almost vertically, into the cavity of the pelvis, where it always divides, near its origin, into several branches, which vary in size, and are not always arranged exactly in the same manner, and do not arise from it constantly. It thus distributes the blood to all the parts within the pelvis, to its parietes, and to the muscles which surround it. It is always more or less evidently divided into two branches, a posterior and an anterior.

§ 1473. The posterior branch gives constantly the gluteal, the ileo lumbar, the lateral sacral , and the obturator arteries. From the anterior arise the ischiatic , the umbilical , and the internal pudic arteries, which usually give off the middle hemorrhoidal , the uterine , the vaginal, and the vesical arteries. Frequently however the secondary branches, particularly those of the posterior branch, arise from the 'trunk of the hypogastric artery, or from the anterior branch ; the first is true, particularly of the ileo-lumbar, and the second of the obturator artery ; the two latter not unfrequently do not arise from the hypogastric artery but very far from the usual place, either from the primitive iliac or from the crural artery.

I. IHO-LUMBAR ARTERY.

§ 1474. The ileo-lumbar artery (A. ileo-lumhalis ) is usually the first, which arises from the posterior branch of the hypogastric artery, and is frequently divided into several, sometimes into three or four, trunks, which come from different points. Not unfrequently it partially or wholly arises from the primitive iliac, from the trunk of the hypogastric artery, from the anterior branch of the latter, or from the crural artery, or, as happens particularly on the left side, from the middle sacral artery, or, finally, it forms a common trunk with the lastl umbar artery. Its volume is by no means always the same.

It goes almost horizontally outward and backward, and soon divides, usually near the sacro-iliac symphysis, into an ascending and a descending branch.

The ascending branch ascends between the psoas and iliacus muscles, to which it sends ramifications, anastomoses with the inferior lumbar artery, which it sometimes entirely replaces, or which in other cases takes its place, and either alone or with the latter, sends branches into the spinal canal through the last intervertebral foramen of the lumbar region.

The inferior branch is more or less transverse, although a little oblique from above downward ; it goes outward, and divides into superficial and deep branches.

The former are distributed on the anterior face of the psoas and iliacus muscles. The others between the latter and the os ilium, enter the muscle through its attached face, and thus penetrate into the substance of the bone through several foramina of nutrition.

All these branches proceed outward and forward, and frequently communicate with those of the circumflex iliac artery.

The anterior branches are distinct, and usually arise from the anterior branch of the hypogastric artery ; they are small, and go to the iliacus and psoas muscles. When the ilio-lumbar artery divides into two large branches it often gives off only an ascending and a descending branch ; but the superficial portion of the descending branch is frequently a part of the superior, and the anterior is formed only by the deep branches.

II. LATERAL SACRAL ARTERY.

§ 1475. The lateral sacral artery (A. sacra lateralis ), is perhaps more frequently double than single, and is sometimes given off by the trunk of the hypogastric or by the ileo-lumbar artery ; hr some subjects it is the first artery of the posterior branch of the hypogastric when the preceding artery arises from another point. It is rarely given off by the primitive iliac artery. It goes backward and inward and descends on the anterior face of the sacrum, before the anterior sacral foramina.

In this course it divides into internal and posterior branches.

The internal are distributed on the anterior face of the false vertebrae of the sacrum, to which they give their branches, and anastomose with the lateral branches of the middle sacral artery (§ 1470).

The posterior or external penetrate in the anterior sacral foramina and soon divide into branches, an anterior, distributed on the posterior face of the body, and a posterior, which emerges from the posterior sacral foramen, and is distributed in the lower part of the muscles of the back.

All these branches give twigs to the lumbar and sacral nerves, also to the membranes of the spinal marrow, and anastomose with the anterior spinal artery.

When the lateral sacral artery is double, the upper portion, which goes only backward, is usually separated from the lower ; but in this case it does not always come from the trunk of the hypogastric or from the ileo-lumbar artery ; it as often arises above the inferior portion, before the posterior branch of the hypogastric artery.

III. OBTURATOR ARTERY.

§ 1476. The obturator artery (A. obturatoria ) is very inconstant in its origin. It usually arises from the posterior branch of the hypogastric artery, whence it comes directly or by a trunk in common with the ileo-lumbar artery, but frequently, at least once in ten times, is given off at another part.

The general character of all these differences in. its origin is, that it arises farther outward and forward.

The anomaly is least when the obturator artery arises from the hypogastric artery above and before the place where the latter divides into an anterior and a posterior branch.

Next come the cases where it arises from the anterior branch of the hypogastric artery.

The anomaly is still greater when it arises from the primitive iliac artery. The latter gives it off either within or without the cavity of the pelvis, sometimes directly and sometimes indirectly.

It arises from different parts of the inner and outer portion of the primitive iliac artery.

Sometimes it is given off by the superficial femoral artery, two inches below Poupart’s ligament.

When it is not a direct branch of the crural artery, it arises by a trunk in common with the epigastric artery. The most usual case, which is almost as common as that where the artery arises from the hypogastric artery, is, according to our observations, as 16 : 1, in respect to its frequency with that where it arises directly from the crural artery.

The common trunk varies in length from two lines to two inches, but it is usually short and its origin is no higher or lower than usual ; in both cases however its length exceeds the rule.

But in all these anomalies, however remotely the obturator artery may arise from its usual place, it always passes on the horizontal branch of the pubis to enter into the cavity of the pelvis and be distributed as usual, and emerges from this cavity through the obturator foramen. This peculiarity is an important argument in support of the law, that when the organization presents an anomaly it always approximates as much as possible to the normal state.

Between the cases where the obturator artery arises from the hypogastric artery and where it comes from the crural artery, we find an intermediate case, where it arises from the union of two branches nearly equal in size, an anterior and a posterior, which arise, the former from the epigastric or the crural artery, the other from the hypogastric artery, and which anastomose at an acute angle.

It is. pleasant to observe that these differences are indicated in the most normal formation, since a smaller or larger anastomosing branch always passes above the horizontal branch of the pubis, extends from the obturator artery given off by the hypogastric artery to the crural or to the epigastric artery. Consequently the internal obturator artery always arises to a certain extent from an anterior and a posterior branch. When the posterior is more developed, the artery seems at first view to come principally from the hypogastric artery, while, when the anterior branch is larger than the other, we are led to conclude that the obturator artery arises from the femoral or from the epigastric artery.(l)

(1) These anomalies in the origan of the obturator artery arc common, as we have already remarked. Portal, although he asserts that the origin of this vessel is very inconstant, brings forward as proof only the cases where it arises from the trunk or from the branches of the hypogastric artery, but when describing this or the epigastric artery, he mentions those only where it arises from the latter or from the crural artery. Mayer only remarks that the obturator artery is sometimes given offby the crural or by the epigastric artery. Hildebrandt does not mention, when speaking of the obturator or of the epigastric artery, the anomaly which occurs when the first arises from the second, although this is more common than when it arises from the crural artery. He only says that it comes from the hypogastric or from the crural artery, and thus he at least indicates the frequency of the latter arrangement. Monro says that it is sometimes given oft' by the epigastric artery (p. 353). Sabatier (p. 108) and Boyer (p. 134) remark that it arises in some subjects from the epigastric or from the crural artery. Murray mentions only those cases where it arises from the epigastric artery. Haller, Scemmerring, Bichat, Hardrops, Burns, Cooper, and Monro

This arrangement of the obturator artery is not necessarily the same on the right and left side, any more than are the varieties of any other artery. It follows however, from our observations, that it is more common or at least as common to find both sides of the body formed after the same type as to find this type only on one side. Thus in most of the preparations before us, the obturator artery comes on both sides from the hypogastric ; in four, it arises by a trunk in common with the epigastric artery, and there are five only in which it arises from the epigastric artery on one side, and on the other, directly from the crural artery by a trunk in common with the epigastric artery.

When the obturator artery arises from the epigastric only on one side, this variety generally occurs on the left. At least our observations have shown that the cases in which it arises from the left epigastric artery are to those where it comes from the right as 10 : 1. We do not think that sex has any influence in this respect ; we have not observed that the origin of the obturator artery outward is more common in the female than in the male, as Hesselbach asserts.

§ 1477. Most commonly, when the obturator is a branch of the hypogastric artery, it goes outward and forward, directly below the upper edge of the cavity of the pelvis, gives off in its progress some inconstant ramuscules to the levator ani and obturator internus muscles, to the glands of the pelvis, and to the obturator nerve which accompanies it, passes through the upper and tendinous part of the obturator intemus muscle, at the upper part of the obturator foramen, and emerges from the pelvis to be distributed to the upper and internal part of the thigh. It usually gives off also, before leaving the pelvis, a branch, which anastomoses with a corresponding branch of the opposite side on the symphysis pubis, and always gives origin to a branch, which varies in size and anastomoses with the epigastric artery above the horizontal branch of the pubis

have written the best upon this artery. Haller says ( Ic.fasc . x. expl. tab. i. not. 9) : Non tarnen perpetuum est, earn arteriam a pelvis truncis nasci, cum novies viderim ex epigastrica ortam. Scemmerriug expresses himself with much exactness. This artery, he says, is not constant in its origin ; it sometimes arises from the crural and often from the epigastric artery (p. 294). Bichat also mentions the frequency of this last origin. Wardrop says he has observed it in many subjects. The details on the origin and distribution of this artery given by Burns are most correct ; they perfectly agree with our own observations. He says the obturator artery is usually regarded as a branch of the internal iliac artery, but wc have as good right to assert that it arises from the trunk or from one of the branches of the external iliac. We have often seen it come from this vessel, an inch above Poupart’s ligament. It frequently arises by a trunk in common with the epigastric artery. These details are given in his treatise on diseases of the heart. Farther (Observations on the structure of the parts contained in crural hernia ; in the Edinb. Med. and Surg. Journ., voL ii. p. 272), he says that the obturator and the epigastric arteries often arise by a common trunk ; perhaps however this arrangement may be considered as a rare anomaly, but he has observed it more than twenty times. Cooper ( 77te anatomy and surgical treatment of crural and umbilical hernia, 1807, Edinb. Med. and Surg. Journ., vol. iv. p. 231) also states, when speaking of the origin of the obturator and epigastric arteries by a common trunk, that it is not rare. Monro (Anat. of the gullet , p. 429) establishes the relation between this case and those where it does not exist as 1 : 10. Bekkers also mentions (Diss. de hernia inguinali, Paris, 1813) three cases observed by himself, in which these two vessels arose in common from the external iliac artery. We have mentioned these cases, which support our observations, because Hesselbach (Neueste anatomisch-pathologisch Untersuchungen über den Ursprung und das Fortschreiten der Leisten-und Schenckelbrüche, Wurzburg, 1815) is wrong on this subject. He maintains, which seems impossible in so distinguished an anatomist, not only that this variety is very rare but adds, that, as to his knowledge the lesion of this artery has been observed only in females, the injury of the obturator artery in the male is not to be feared.

In or directly before the obturator foramen, the obturator artery usually divides into two branches, an external and an internal.

The internal branch is smaller and passes above the obturator externus muscle, gives branches to it and also to the adductor brevis and longus, to the gracilis, to the pectineus, and to the skin of the internal part of the thigh, the scrotum or the labia pudenda, commonly anastomoses with the internal circumflex artery of the thigh, and with the external branch on the circumference of the obturator foramen, and with the external pudic artery in the scrotum and the labia pudenda.

The external branch descends deeply outward between the obturator internus and extemus muscles, gives branches to these muscles in which it sometimes terminates, is reflected from within outward on the articular capsule and the inner part of the articulation to emerge from the obturator foramen, and passing behind the quadratus femoris muscle goes transversely to the posterior part of the extremity ; then it is distributed to the quadratus femoris, to the gastrocnemii, to the adductor longus and brevis, to the upper extremity of the flexors of the leg, Anally, to the substance of the external condyle of the femur ; anastomoses with the internal branch on the circumference of the obturator foramen and with the ischiatic artery above, and within with the internal circumflex and the internal hemorrhoidal arteries.

§ 1478. The varieties in the origin of the obturator artery are very important to the surgeon. When this artery arises at the usual place from the hypogastric or from the crural artery within the pelvis, and even from the epigastric artery, but far above the crural arch, it is not exposed to be wounded in any of the common operations. But when its origin is situated very low, audit comes either from the crural artery or by a trunk in common with the epigastric artery, as it then always re-enters the pelvis over the branch of the pubis, it is exposed to wounds in the operation for crural hernia.

When the common trunk of this and the epigastric artery is short, it is generally thrown outward toward the ischium in crural hernia, so that it would be divided if the incision should be made in this directional)

When, on the contrary, this same trunk is long and the obturator artery consequently goes farther inward, it is pushed down by the crural hernia and proceeds before the neck of the tumor inward. (2)

(1) See a case of this kind figured in Monro, Morbid anatomy of the human gullet, Edinburgh, 1811, tab. xiv. fig. 1.

(2) Wardrop has figured a case of this kind (Kd.inb. Med. and Surg. Journ., vol. ii. p. 203), and points out the means of avoiding the obturator artery in this case. See

We must however in this case determine whether the crural hernia is situated more or less outwardly.

If an external and an internal crural hernia exist on one side, thi obturator artery sometimes passes to the inside of the external tumor, even when the common trunk of this vessel and of the epigastric artery is short, and enters the cavity of the pelvis between the two tumors. This has been observed by Burns.

If the obturator artery rises far below the usual place and from the crural artery, either directly or by a trunk in common with the epigastric artery, it generally proceeds deeply, along the pectineus muscle, on the inside of the crural vein, so that, being situated behind the tumor, in case of crural hernia it cannot be wounded in the operation.

But if it was nearer the surface, it might be situated also on the anterior face of the tumor. We have never seen this latter arrangement. Bums and Monro have observed only the first.

IV. GLUTEAL ARTERY.

§ 1479. The gluteal or posterior iliac artery (Jl. glutea, s. iliaca posterior , s. externa ), the largest artery of the posterior branch of the hypogastric artery, which may be considered as its continuation, arises very often by a trunk in common with the ischiatic artery. Sometimes it furnishes the lateral sacral, the obturator, and all the other arteries which usually come from the posterior branch of the hypogastric artery. It goes downward, forward, and outward, toward the lower part of the ossa ilia, usually sends off, in this course, branches to the iliacus inturnus muscle, to the obturator internus, to the pyriformis, to the levator ani, and to the os pubis, then emerges from the pelvis through the ischiatic notch, between the pyriformis and the gluteus minimus muscle, is reflected from below upward, penetrates between the gluteus médius and minimus muscles, and divides into numerous branches, which are distributed to the pyriformis and to the three glutei muscles and anastomose above with the epigastric, the last lumbar, and ilio-lumbar arteries, below with the ischiatic and with the external circumflex artery.

§ 1480. The anterior branch of the hypogastric artery gives off, first, the ischiatic artery, the internal pudic, and the umbilical arteries. The vesical, uterine, and vaginal arteries come from one of the latter ; sometimes also they arise by a common trunk.

V. ISCHIATIC ARTERY.

§ 1481. The ischiatic artery (Jl. ischiadica) arises separate from the internal pudic artery less frequently than by a trunk, which varies in length, in common with the latter, and often by a trunk in common with the gluteal artery. It descends before the latter, but at the ischiatic notch it turns backward, continuing still to descend, and Emerges from the pelvis, below the pyriformis muscle.

Burns, Observations on the structure of the parts contained in crural hernia , in the Edinburgh Med. and Surg. Journ., vol. ii. p. 273, fig'. 1.

The common trunk of the ischiatic and of the internal pudic arteries frequently does not bifurcate, except in this place, to give origin to two arteries ; and from its portion within the pelvic cavity arise branches which are distributed to the pyriformis, to the obturator internus, and to the levator ani muscles.

On emerging from the pelvis the ischiatic artery sends, to the posterior part of the ilio-femoral articulation, branches which anastomose with the circumflex arteries. It afterward goes backward, toward the gluteus maximus muscle, into which it penetrates from within outward, and within which it is almost entirely distributed.

It often gives off the middle hemorrhoidal, the uterine, the vaginal, and the vesical arteries, especially when it arises by a long trunk, in common with the internal pudic artery.

It not unfrequently gives off an inferior lateral sacral artery when the usual artery of this name does not descend very low, and is unusually small.

It constantly anastomoses by large branches, above, with the ischiatic artery, and with the circumflex arteries below, around, thecoxo-femoral articulation of the large trochanter.

VI. INTERNAL PUDIC ARTERY.

§ 1482. The internal jmclic artery (A. pudenda interna , s. communis , s. circumflexa , s. pudica pelviena, s. hœmorrhoidea externa ) descends into the pelvis, directly before the ischiatic artery, which is generally larger than it, and when it is not given off in this place or even afterward by the latter, emerges with it from the cavity of the pelvis, between the pyriformis muscle and the large sacro-sciatic ligament, between the latter and the small sacro-sciatic ligament, afterward re-enters the pelvis, where it continues to the symphysis pubis, descends along the posterior edge of the descending branch of the ischium, on its internal face, to the tuberosity of the ischium, then reascends, always on the inner side of the bene, along its ascending branch and the descending branch of the pubis, between the obturator internus and the levator ani muscles, and having come above the symphysis pubis, terminates in the external organs of generation.

Thus the pudic artery usually emerges from the pelvis through the sciatic notch, and re-enters it between the two sacro-sciatic ligaments to leave it a second time below the symphysis pubis ; but not unfrequently, especially in the male, it always continues in the cavity of the pelvis, and then, proceeding on the lower and lateral portion of the bladder, it goes forward, across the upper part of the prostate gland, where Burns remarks it may be wounded in the operation of lithotomy particularly when the summit of the prostate gland is cut.

It often gives off within the pelvis one or several vesical arteries, the middle hemorrhoidal, the vaginal, or the uterine, and even the obtm rator arteries. It also sends smaller branches to the internal parts of the genital and urinary apparatus. In its course along the descending branch of the ischium, besides several small branches which go to the bone, to the obturator internus muscle, to the upper extremity of the flexor muscles of the thigh, to the lower part of the rectum, and to the sphincter ani, it gives off others also, of which the principal are,

1st. A considerable branch which goes outward, between the large trochanter and the ischium, divides into several branches, descends on the neck of the femur and the capsule of the ilio-femoral articulation, between the obturator internus and externus muscles, gives ramuscules to these muscles, and also to the quadratus femoris and to the gemelli muscles, and anastomoses with the circumflex arteries.

2d. One or more rather large internal branches, which go to the inferior part of the rectum, also to the anus, and form the external or inferior hemorrhoidal artery (A. hcemorrhoidea externa , s. inferior).

A little above the tuberosity of the ischium, the internal pudic artery divides into two branches, an internal transverse, and an external anterior ascending branch.

The internal branch, the perineal artery ( R . interims , s. transversus , s. superficialis, arteria perinœa , s. transversa perinœi) is smaller than the external. It goes inward and a little forward along the transversalis perinei muscle, usually between it and the skin, distributes branches to these parts, and also to the other muscles of the penis, and to the constrictor vaginae in the female ; gives some branches to the lower part of the rectum, and to the sphincter ani, which are termed the external or inferior hemorrhoidal arteries (A. hœmorrhoidales inferiores, s. externes ,) and sends others also to the skin of the perineum, labia pudenda, and scrotum.

The external , anterior, superior, or deep branch ( R . anterior, s. superior, s. profundus , s. pudendus) is called the artery of the penis (A. penis) in the male, and the artery of the clitoris {A. clitoridea) in the female. When the internal pudic artery gives off considerable branches within the pelvis, this artery not unfrequently arises mostly from the other adjacent branches' of the hypogastric artery, especially from the obturator artery, less frequently from the external iliac artery, particularly from an external pudic artery, an anomaly which is indicated in the normal state by the more or less manifest anastomoses between the internal and the external pudic arteries.

This artery is much larger in the male than in the female on account of the greater proportional size of the parts to which it is distributed.

In both sexes it proceeds from below upward, around the inner face of the pubis and ischium, between the bone and the corpus cavernosum of the penis and clitoris, and distributes branches to the vagina and prostate gland, the labia pudenda, and the scrotum, finally to the clitoris and the penis, which branches are arranged after the same type.

The branches which go to the prostate gland and the scrotum in the male, to the vagina and to the labia pudenda in the female, are given oft' the first, directly above the sciatic tuberosity.

After these the trunk descends along the ischium and the pubis, covered by the erector penis ( levator penis, clitoris ), and thus comes into the triangular space below the symphysis pubis, where the roots of the cdrpus cavernosum of the penis in the male, and of the clitoris in the female unite.

In both sexes, the artery then divides into two branches, the superficial and the deep branch.

The superficial or the dorsal branch, the dorsal artery of the penis or clitoris (R. dorsalis, s. superficialis penis vel cliioridis), passes through the suspensory ligament. It is very tortuous when the penis is not erected, and proceeds under the skin at the side of the synonymous artery of the opposite side, with which it sometimes unites, after a very short course, advances thus on the back of the penis, and gives branches to its skin and its fibrous membrane, and sends off others which descend into the scrotum. At the groove behind the glans, it forms a crown around it, and finally penetrates into its substance.

The deep branch or the cavernous artery ( Jl. profunda , s. cavernosa penis, s. cliioridis) passes through the fibrous membrane of the corpus cavernosum of its side, thus penetrates into the substance of this body, and soon divides into several branches. These proceed from behind forward, along the penis, expand in the corpus cavernosum of both the penis and urethra, and frequently anastomose with those of the opposite side.

The two deep branches often unite in a single common trunk.

Sometimes the internal pudic artery terminates much sooner than we have mentioned, in the transverse perineal artery, and the dorsal artery of the penis or clitoris arises wholly or in great part from the obturator artery.

VII. UMBILICAL ARTERY.

§ 1483. The third artery of the anterior branch of the hypogastric artery, the umbilical artery ( A . umbilicalis), is before birth the continuation not only of the trunk of this artery, or even of the primitive iliac artery, but is larger than the hypogastric and femoral arteries, and is the continuation of the aorta.

At all periods of life the umbilical artery goes a little obliquely forward and inward, toward the upper part of the lateral wall of the bladder, to which it is attached by mucous tissue. Thence it proceeds along this wall, toward the posterior face of the anterior wall of the abdomen, and thus goes from behind forward and from below upward to the umbilicus.

In the fetus it is open in its whole extent, but soon after birth it is gradually obliterated after leaving the umbilicus, so that finally it affords a passage to the blood only in the part between its origin and the bladder, the rest of it being changed into a full and solid ligament, enveloped by a fold of the peritoneum, and which may be generally traced to the umbilicus.

During fetal existence, the lower and anterior part of the umbilical artery which is convex, gives off not only the branches of the hypogastric artery, which we described above, but also, first, the inferior vesical, then the vaginal, next the uterine, and finally one or more superior vesical arteries, which generally are very distinct from each other. But as it is gradually obliterated, and as at the same time the lower extremities and their vessels are developed, these arteries approach each other, and seem to be in part the upper arteries of the anterior branch of the hypogastric artery.

These branches arise in the following order, which we adopt, since in following it the arteries to be described, correspond from behind forward to those already mentioned.

VIII. VESICAL ASTERIES.

§ 1484. The vesicul arteries (A. vesicates) are distinguished into inferior and superior.

The inferior are larger than the superior, and generally there is only one. They arise from the umbilical or from an anterior branch of the hypogastric artery, which is usually the internal pudic, or from the trunk of the hypogastric artery ; they go downward and forward to the lower and posterior part, and also to the neck of the bladder, the commencement of the urethra, to the prostate gland and to the vesiculæ séminales in the male, and to the lower part of the vagina in the female.

The superior are generally smaller and more numerous; they always arise from the lower part of the umbilical artery, consequently from the most anterior part or from the extremity of the hypogastric artery, and go to the middle and superior part of the bladder.

IX. MIDDLE HEMORRHOIDAL ARTERY.

§ 1485. The middle hemorrhoidal artery (A. hœmorrhoidea media) often follows the inferior vesical artery from below upward, and from behind forward ; but frequently also it arises lower than it, being even sometimes deficient, and is given off by the ischiatic or by the internal pudic artery. Sometimes it arises from the upper or lower hemorrhoidal arteries, with which it always anastomoses, and is distributed on the anterior face of the rectum and also on the posterior part of the bladder, where it communicates with the proper vesical arteries.

X. VAGINAL ARTERIES.

§ 1486. One or two vaginal arteries ( A . vaginalis ) usually follow the inferior vesical artery. But this artery is frequently deficient, and it is then replaced by the ramifications of the vesical, the hemorrhoidal, or the uterine arteries. Sometimes also, even when it forms a distinct branch, it does not arise in the order mentioned, but comes from some one of the arteries of the anterior or of the posterior branch of the hypogastric artery.

It goes forward, inward, and downward. Its branches are distributed to the inferior and middle regions of the lateral part of the bladder and of the vagina.

XI. UTERINE ARTERY.

§ 1487. The uterine artery (Jl. uterina) generally succeeds the vaginal artery, but it frequently varies from this order. It is however constant.

It goes inward, toward the upper part of the vagina, to which it gives off some branches, as well as to the bladder ; it then reascends in the broad ligament along the lateral wall of the uterus. In its course which is very tortuous, it gives off numerous ramifications which are also curved, to the anterior and posterior faces of the uterus. Some of these ramifications are distributed on the surface and others in the substance of this organ.

Its upper part expands by several branches in the folds of the peritoneum ; they go to the internal organs of generation, to the Fallopian tubes, and to the ovaries, where they frequently anastomose with the spermatic arteries.

§ 1488. In man, the vessels which correspond to the uterine or the vaginal arteries are small secondary branches of the vesical and of the external hemorrhoidal arteries.

2. External Iliac Artery

§ 1489. The external or anterior iliac artery (.fl. iliaca externa , s. anterior , s. cruralis iliaca , s. femoralis), from its origin, descends from within outward, on the inside of the psoas magnus muscle, sends numerous small branches to this muscle, and also to the lower part of the iliacus muscle.

It usually gives off, at a greater or less distance from the crural arch, two large branches, the epigastric artery, and the circumflex iliac artery, which are very important in a pathological and surgical point of view on account of inguinal and crural hernias.

The first usually arises a little and sometimes much higher than the second, and even above the crural arch ; besides, it always comes from the inside of the iliac artery, while the other constantly arises from its outside.

1. EPIGASTRIC ARTERY.

§ 1490. The epigastric artery {A. epigastrica) is rarely a branch of the common or deep crural artery,(l) but it often arises by a trunk, in common with the obturator artery, so that we may consider it as giving off this latter(2) (§ 1476), although, for all this, its origin is not necessarily displaced and carried higher than usual. It is often given off. sometimes higher and sometimes lower, from the external iliac artery, so that the place where it arises varies to the extent of two inches, although the obturator artery is not necessarily one of its branches. (3) Thus we may consider erroneous the opinion of Hesselbach, who asserts that this artery rarely varies in its origin and in its course, (4) and also that of Mayer,(5) who, like Burns, asserts that it always arises directly below the crural arch. The latter case exists very seldom, for the epigastric artery almost always arises above Poupart’s ligament. On the contrary, the place where it detaches itself from the external iliac artery varies much, although it never comes fiom any other vessel. (6) It however generally arises directly above the crural

arch, (7) and its origin is normal when situated one inch or even two inches above this arch.(8).

(1) Monro, Morbid anatomy of the human gullet, Edinburgh, 1811, p. 426.

(2) At least we have never found in this case that the epigastric was a branch of the obturator artery, although we have olten seen both arise by a common trunk, and have now several cases of the anomaly before us. Hesselbach, ( Ueber den Orprung und das Fortschreiten der Leisten-und Schenkelbrüche, Wurtsburg, p. 17) and Bekkers ( loc . cit., p. 315), mention in fact one case where the epigastric arose from the obturator artery. But it is evidently wrong, as it follows from the description of this anomaly given by the former, in saying that the obturator artery came from the inside of the crural more than an inch above the crural arch ; since it follows from it we say that the common trunk arose, as is commonly seen in this case, from the external iliac, and not from the internal iliac, or hypogastric artery, as would be the case provided the expressions of Hesselbach weie correct. This anomaly however may sometimes occur. Monro (loc. cit., p. 427) seems to have observed it, for he says that in one preparation before him the epigastric arose from the obturator artery, and afterward went upward and inward, toward the rectus abdominus muscle.

(3) Which Hesseloach seems to think necessary.

(4) Hesselbach, loc. cit., p. 17-52.

(5) Mayer, Beschreibung der Blutgefässe des menschlichen Körpers , p. 206.

(6) Monro is very correct in saying (loc. cit., p. 254) that the epigastric artery varies much in its origin.

(7) As has been correctly stated by Bichat (loc. cit., p. 311) and Murrav, (loc. cit.. p. 89).

(8) Outlines, p. 354.

(9) According to Sœmmerring, lor. cit., p. 307.

When the epigastric artery arises unusually high it descends near the crural arch, sometimes very low, even below this arch, and always passes behind the commencement of the spermatic cord, above the inguinal ring, so that it is situated on the inside of this cord. There it suddenly curves and reascends vertically on the posterior face of the rectus abdominis muscle, first between this muscle and the peritoneum, then between it and the posterior layer of the sheath.

Soon after it is reflected around the spermatic cord, it gives off, directly above the inguinal ring, a constant branch, which divides into two branches ; one goes downward and backward and anastomoses with the iliac artery, the other is transverse and goes inward, proceeds along the horizontal branch of the pubis, behind the inguinal ring, and communicates with that of the opposite side. It also sends to the spermatic cord or to the round ligament of the uterus, some ramifications which penetrate to the scrotum and the labia pudenda, and anastomose below with the spermatic arteries, and above with the uterine arteries in the female. These ramifications, which go to the spermatic cord and to the round ligament of the uterus, sometimes come from the trunk of the external iliac, even above the epigastric artery, when the latter arises lower than usual. This arrangement coincides with the very high origin of the spermatic arteries notwithstanding the sloping situation of the testicles and of the ovaries, since it manifestly depends on the spermatic cord being situated at first higher and more internally.

The trunk of the epigastric artery divides below into two branches, the external, which is generally the larger, and the internal, the smaller ; it then ascends on the posterior face and in the substance of the rectus abdominis muscle, sends off several branches outwardly, one of which is frequently larger than the others, in the internal part of the broad abdominal muscles, gives branches to these, the recti, and to the pyramidales muscles, and to the peritoneum, and terminates near the centre of the abdomen, by anastomosing with the branches of the external thoracic, the inferior intercostal, and the internal mammary arteries.

The epigastric artery is situated on the outside of the tumor in internal inguinal hernia, and on the inside in external inguinal hernia ; so that in the former case it is wounded when the incision is carried outward and in the latter case when the bistçry is directed inward. It is rarely so far distant from the inside that it is raised with the umbilical artery or with the remnant of this vessel, and consequently proceeds on the inside of the tumor, even in an internal inguinal hernia.(l) In crural hernia it is usually found outward, so that we run the risk of opening it when we cut in this direction. It is however difficult to wound it when it does not arise lower than usual, while this is easy when it comes from the crural artery, in which case it sometimes ascends on the outside of the inguinal ring, sometimes passes before this opening to go to its inside ; it may also be divided, when, although it does not arise lower than usual, it descends first superficially and resumes its situation afterward to go toward the umbilicus.

(1.) Bekkers, he, cit, p. 316

§ 1491. Sometimes a considerable branch arises from the inside of the iliac artery, below this artery, the following, or finally the crural arch. This is half as large as the epigastric artery, and ascends outside of the inguinal ring, between the external face of the obliquus abdominis muscle and the skin, gives branches to this muscle, particularly to the integuments, extends to the umbilical region, anastomoses below with the epigastric artery, and may be considered as the second epigastric artery. When this branch exists, it is also found on the outside of the tumor in an external inguinal hernia, and it is wounded if the bistory is carried in that direction.

II. CIRTUMFLEX ILIAC ARTERV.

§ 1491. The circumflex or anterior iliac artery {Jl. abdominalis , s. civcumflexa iliaca externa , s. iliaca externa minor , s. epigastrica externa ) usually arises on the outside of the iliac artery, opposite the epigastric artery, which is generally a little larger than it. As however it is more constant in its origin than the latter, it is not unfrequently placed more or less below it. It frequently comes from above the epigastric artery, although the latter arises at its usual place. In some subjects it even arises from the crural artery, directly below the crural arch, but always at least from its outside. It goes directly outward and upward toward the iliac crest, frequently sends branches to the tensor fasciae latæ and sartorius muscles, always give them to the iliacus muscle, and following the direction of the crest of the ilium, proceeds from before backward and from within outward, in the lower and middle part of the broad abdominal muscles, between which its principal branches penetrate. The latter anastomose with the ileo-lumbar and epigastric arteries. Others, which go outward, toward the great trochanter and the sartorius muscle which they accompany, communicate with the ramifications of the crural artery.

This artery is not unfrequently divided into two trunks, one of which generally arises a little below the epigastric artery.

The external branch is generally much larger than the other, but sometimes becomes a small branch, while the principal branches of the artery go obliquely inward and upward. In this case, when one or more of these branches are considerably large, the operation of paracentesis might give rise to a formidable hemorrhage. (1)

(1) Ramsay, Account of some uncommon muscles and vessels, in the Edinb. med. and surg. jmtrn., vol. viii. p. 282, tab. 1, fig'. 1.

3. Crural Artery

§ 1493. The external iliac artery after emerging from the crural arch, under the centre of which it passes, is called the crural or femoral artery [A. cruralis, s. femoralis communis s. cruralis inguinalis , s. cruri inguinalis). It is situated in this place on the neck of the femur, almost directly below the skin, covered only by the fascia lata aponeurosis, the fat, and the lymphatic glands of this region, over the vein which accompanies it, and occupies nearly the centre of the space between the symphysis pubis and the anterior and superior spine of the ilium, between the adductor muscles of the thigh on one side, the rectus anticus and the sartorius muscles on the other.

Beside the small inconstant ramifications which it distributes to the skin, to the muscles, and to the lymphatic glands of this region, it gives off, sometimes higher and sometimes lower from its inside, one, two, and even three external pudic , scrotal , or vtdvar arteries, the upper, the lower, and the lowest (A. pudendœ externa , superior, inferior et infima , s. tertia).

These arteries, which proceed directly under the skin, go from without inward in the integuments and the fat of the pubis and of the lower part of the abdomen, the inguinal glands, the scrotum, and the labia pudenda, where they form the anterior scrotal and labial arteries (A. scrotales et labiales anteriores). To this is referred the second epigastric artery mentioned above.

§ 1494. The crural artery has not always the same extent. Its length is principally determined by the origin of the deep femoral artery, which always arises from its posterior and inner side, so as to be covered by it. This branch is generally given off from the trunk one or two inches below the crural arch, rarely higher, (1) but sometimes also it arises directly below the arch or even, which is always very rare, above it. On these differences depend also those in the size of the superficial and deep crural arteries or of the continuation of the trunk. When the crural artery arises very high it is usually much larger than common, nearly equal to the superficial in size, and then it frequently gives off the upper branches of the latter, particularly the external pudic arteries, but more frequently still the circumflex arteries, which we shall mention directly. Sometimes the latter and the deep crural artery arise from a common trunk and at the same place.

(I) Burns has already corrected the error made by Bell, who asserted that this division usually occurred four inches above the crural arch.

I. DEEP CRURAL ARTERY.

§ 1495. The deep crural artery (A. cruralis , s. femoralis profunda) gives off frequently, not far from its origin, two branches, called the circumflex arteries of the thigh (A. circumjlerœ femoris ), which are distinguished into external and internal. This however is not always the case. Sometimes, but very rarely, these two arteries (more frequently one of them, particularly the internal, and very rarely the external) arise from the common crural or even from the superficial crural artery, below the origin of the deep femoral artery,

I» CIRCUMFLEX ARTERIES.

§ 1496. The internal circumflex artery {A. circumflexa femoris interna ) generally arises higher than the external. Its origin is sometimes two or three inches above that of the latter ; hence it comes more frequently than the other from the common crural artery, directly below the crural arch and the epigastric artery, higher even than the three external pudic arteries, and it is thus sometimes given off by the external iliac artery. It generally comes from the inside, but in some subjects from the outside of the common crural artery. In this case it gives one or more branches, which go outward and upward, into the inguinal glands, the iliacus and the sartorius muscles, and anastomose with those which arise from the crural artery. The trunk goes inward, passing in the second case below the crural artery, and at the same time descending a little when not unusually high. It gives branches to the lower part of the psoas and iliacus, the pectineus, to the short and long adductor muscles, afterward goes deeply inward and backward, below the pectineus muscle, and immediately around the neck of the femur, and divides behind the pectineus into two branches, a superior or anterior and an inferior or posterior.

The superior is smaller and soon subdivides into two branches ; the external and smaller is called the artery of the cotyloid cavity (A. acetabuli) ; it goes to the capsular ligament and to all parts of the articulation, turns on the head of the femur, anastomoses by a large ramus cule with the obturator artery, and distributes branches to the obturator externus muscle. The internal is larger, passes behind the adductor longus and brevis, and is expanded in the upper part of the adductor magnus muscle.

The inferior branch is much larger than the preceding, and is the continuation of the trunk. It descends backward, behind the adductor magnus muscle, is distributed principally to the gracilis muscle, the three long flexors of the leg, the long head of the biceps femoris, the semimembranosus and the semitendinosus, and finally becoming sometimes one, sometimes two branches, called the trochanterian, which are distinguished into an upper and lower (R. trochantericus superior et inferior), it is reflected from before backward, on the inner part of the femur, then outward and upward, to arrive at the great trochanter, ascends before the gemelli and quadratus femoris muscles, between them and the obturator externus muscle, gives branches to these muscles, and also to the tendon of the obturator internus and pyriformis, and anastomoses with the external circumflex, the gluteal, the ischiatic the inferior hemorrhoidal, and the obturator arteries. This inferior branch is sometimes smaller, and is distributed only to a portion of the adductor magnus and to the gracilis muscles ; all the other ramifications, especially the anastomotic, arising from the superior.

Beside the anastomoses between the external and the internal circumflex arteries at the posterior part of the thigh, these two arteries often unite by a very large transverse branch on the anterior face of the bone, which, added to their communication with the crural artery, completes the circle of anastomosis.

By all these anastomoses the internal circumflex artery is the principal channel through which the blood comes to the lower extremity when the external iliac artery is tied. It is consequently one of those vessels which are considerably dilated after this operation.(I)

§ 1497. The external circumflex artery (Jl. circumflexa femoris ex terna) arises still more frequently than the preceding, although not always from the outside of the deep crural artery. It comes sometimes from the place where this latter is given off from the common femoral artery, and sometimes much lower.

It goes obliquely outward, turning on the anterior face of the femur, directly on the upper part of the cruræus muscle, gives small branches to the lower extremity of the iliacus muscle, and soon divides into an ascending and a descending branch.

The descending branch which arises sometimes wholly, sometimes partially, from the superficial or from the deep femoral artery, gives ramuscules to almost all the outer part of the triceps extensor, also to a small portion of the rectus femoris muscle, and sends upward, across this muscle, a transverse vessel which goes to the large trochanter, penetrates into its substance, and forms a net work on its surface by anastomosing with the ramifications of the internal circumflex artery.

The ascending branch penetrates from before backward and from within outward, principally into the gluteus médius muscle, passes above the great trochanter, and anastomoses in this place with the internal circumflex, the gluteal, and the ischiatic arteries.

These anastomoses are also very much dilated when the external iliac artery is tied.

II. PERFORATING ARTERIES.

§ 1498. The deep femoral artery after giving off the circumflex arteries goes backward, inward, and downward, so that it descends on the inside of the femur, between the vastus internus externally, the adductor longus and brevis internally, and the superficial femoral artery forward. In this course it generally gives off some anterior and several posterior branches ; the latter are larger and more constant.

(1) A. Cooper, Account of the anastomoses of the arteries of the groin ; Med. Chir. TVans., vol. iv. p. 424.

The anterior generally arise very high from the outer and inner sides of the artery. Sometimes there is only one and sometimes we find several on each side. The external goes to the vastus intemus and penetrate also to the crurales muscle. The internal go to the adductor magnus and adductor brevis muscles, and, passing between these two muscles, arrive at the upper and middle part of the gracilis intemus muscle, of which they are the principal nutritious vessels.

Properly speaking, the trunk of the deep femoral artery divides to give rise to the posterior branches, since it penetrates much farther back, to the posterior part of the thigh behind the femur.

These branches have been termed the perforating arteries (A. femoris perforantes), because they pass through the adductor magnus muscle to the parts behind it.

They vary in number from one to five ; for sometimes the whole trunk, or at least that part from which the perforating arteries generally arise, goes backward, after passing through the summit of the adductor magnus muscle, and then descends behind this muscle, while in other cases it proceeds before it, and gradually gives off branches, which pass through it to arrive at the posterior part of the thigh. This diference is sometimes observed in the two lower extremities of the same subject.

The saper ior or first perforating artery commonly divides into two branches, an upper which ascends, and a lower which descends.

The superior branch ascends toward and around the great trochanter, on which it anastomoses with the ramifications of the external circumflex artery, and penetrates into the lower part of the .gluteus maximus muscle, where it communicates with the gluteal artery.

The inferior branch turns around the femur forward and outward ; it is distributed to the vastus extemus and to the rectus, and to the long head of the biceps muscles. It also gives off the nutritious artery of the femur {A. nutritia ossis femoris ).

The second and third perforating arteries sometimes arise opposite each other, one from the outside the other from the inside of the femoral artery. The external goes to the triceps extensor muscle, the internal is distributed to the biceps, the semitendinosus, and the semimembranosus muscles.

Sometimes we find also two other perforating arteries, an external and an internal, which are distributed in the same manner.

In some subjects the upper branch, then unusually large, is the only one which passes through the adductor magnus muscle. It divides into two branches, an ascending which gives all the internal ramifications to the flexor muscles ; the inferior is larger, and gives off all the external ramifications except the first. The latter is not visible externally, but directly where the adductor magnus muscle is inserted it passes through this muscle to empty itself from within outward, in the vastus externus and the rectus femoris muscles.

The sciatic nerve also receives considerable branches from the perforating arteries.

A large branch, the anterior extremity of the trunk of the deep femoral artery, always descends before the adductor magnus muscle, between it, the adductor longus and brevis muscles, distribute branches to these muscles, and near the centre of the thigh give off the inferior nutritious artery of this bone.

Many of these branches, especially the lower, sometimes arise from the superficial, and not from the deep femoral artery. They all anastomose with each other. Farther the superior, as we have already observed, communicate with the external femoral and the gluteal arteries. The lower and the middle are connected by large anastomosing branches with recurrent branches, which arise from the lower part of the superficial femoral and the popliteal arteries.

Thus when the common or superficial artery is obliterated to a greater or less extent, the perforating branches of the deep femoral artery, and generally all its ramifications, are very much dilated, larger even than the trunk, as is proved by the observations of Deschamps, ( 1 ) Dupuytren, (2) and Astley Cooper. (3)

The deep femoral artery supplies the blood to most of the muscles of the thigh, to almost all the skin of this extremity, and to its bone ; it also gives origin to the accessory vessels for the circulation of the blood in the lower extremity.

II. SUPERFICIAL FEMORAL ARTERY.

§ 1499. The superficial femoral artery (Jî. femoralis superficialis , s. cruralis femoralis, s. cruri-femoralis , s. femoro- tibial is), after the origin of the deep, penetrates a little farther, between the vastus internus on one side and the adductor longus and brevis on the other, passes below the sartorius, to arrive at the inner side of the thigh, proceeds before the adductor muscles to the commencement of the lower fourth of the thigh, enters in this place the tendon of the adductor magnus muscle, and thus comes on the posterior face of the limb, where it is called the popliteal artery.

In its course it gives off branches, of which the principal are the internal and the external ; but it also sends off anterior and particularly posterior branches, especially at its lower part.

The internal branches are distributed in the adductor, the gracilis and the sartorius muscles.

(1) Observ. anat. failcs sur un sujet opéré suivant le procédé de Hunter, d'un anéurysme de l’artère poplitée ; in the Mém. prés, â l’instit., 1805, vol. i. p. 251.

(2) Journ. de Corvisart, vol. vii. p. 536.

(3) Dissection of a limb , on which the operation for popliteal aneurysm had been performed, in the Med. chir. trans ., vol. ii. p. 250.

The external are distributed in the latter, to the rectus, and particularly to the vastus internus ; the deep pass behind the femur, and go to the vastus extemus.

The anterior distribute blood to the sartorius muscle and to the skin-, to which also go some ramifications of the other branches.

The posterior go to the vastus internus, but particularly to the lower part of all the flexors of the leg, and as they turn around the femur they also penetrate into the vastus extemus and extend to the skin. They anastomose by large branches above with the perforating arteries, below with the superior and inferior articular arteries.

The superficial femoral artery deserves its name, because, during its whole course, it is situated near the skin. It is covered for a short distance by the sartorius muscle which crosses it. We may then easily find it in operations. The place where it is exposed in Hunter’s operation for aneurism is directly below the lower edge of the sartorius muscle at the inner part of the anterior side of the thigh.(l) The objection that when we operate in this place the articular arteries are lost and the circulation cannot continue is unfounded, (2) since when the superficial femoral artery is entirely obliterated, the anastomoses of the branches of the deep femoral artery with the lower branches of the superficial, and with those of the popliteal artery, supply channels which are large even in the normal state, and through which the blood may pass from the branches of the deep femoral into the articular arteries, and into all the parts below the ligature,

III. popliteal artery.

§ 1500. The popliteal artery (A. poplitaea , s. cruri-poplitcea, s, femoro-poplitcea) is the lowest portion of the femoral artery, and descends into the calf of the leg, inclining a little from within outward ; it extends from the beginning of the lower fourth of the femur to the summit of the upper fifth of the leg. Sometimes it is much longer, because the superficial femoral artery penetrates the adductor magnus higher, and also divides a little higher.

It is separated at its upper part from the femur and from the posterior face of the capsular ligament of the femoro-tibial articulation at its central part, by an abundance of fat and cellular tissue. The tibialis posticus muscle separates it below from the tibia.

Behind, it is separated at its upper part from the skin by the sciatic nerve and the popliteal vein, by fat and by mucous tissue ; in its lower part, by the muscles of the calf of the leg, and the plantaris muscle.

Above, it is separated by abundance of fat and cellular tissue, outward from the biceps femoris muscle, and inward from the semitendinosus and the semimembranosus muscles. The two upper heads of the triceps extensor muscle closely envelop it at its lower part. It is then looser and also nearer the bone above and below, but is every where surrounded with an abundance of fat and cellular tissue. This circumstance, added to the prominence of the flexor muscles of the tibia and of the fibula, renders it difficult to fix it and to compress it.

(1) Home, An account of Hunter's method of performing the operation for the cure of popliteal aneurysm, in the Trans, of anass. for the improv^oi med. and surg. knowl., vol. i. no. 4. Additional cases, &c. ibid. vol. ii. no. 19 (2) DeschampS, loc. cit ., vol. i. p. 254.

§ 1501. Beside certain inconstant branches which, when it passes through the tendon of the adductor magnus muscle higher than usual, appear near its origin, on the posterior face of the thigh, it gives off,

1st. From its upper part or crural portion, particularly from the posterior and inner side of this portion, several branches, which go to the lower part of the flexor muscles of the tibia.

2d. Lower down three superior articular arteries {Jl. s. rami articulares superior es), which are distinguished into internal, external, and middle, which sometimes, even usually, all, or at least two, arise by a common trunk from the anterior side of the popliteal artery. Some of these arteries are double in some subjects, then only one is detached from the trunk before the other, and the superior anastomoses with the muscular branches mentioned before. The internal and external are usually larger than the middle.

§ 1502. The external superior articular artery (A. articularis genu superior externa ) rests directly on the tibia, and passes between this bone and the common tendon of the biceps muscle, usually goes from below upward, but always from behind forward and from within outward, and gives off, in its course, ramifications to the inferior belly of the biceps muscle, also to the lower part of the vastus externus, is distributed on the outer condyle of the femur, penetrates into the articular capsule, gives branches to all the ligaments of the keee, and communicates, by a very large anastomosing branch which proceeds across to the anterior face of the femoro-tibial articulation, on the common tendon of the extensors of the thigh, on one hand, both on the side and forward with the ascending branches of the external inferior articular artery on the other, on the median line and fonvard, with a similar branch of the internal superior articular artery.

§ 1503 . The internal superior articular artery {Jl. articularis genu superior interna ) varies more than the external and the middle in respect to its origin, for it not only forms a distinct trunk much more frequently than the latter, but it also not unfrequently, in fact almost normally, arises very high, as it sometimes comes from the superficial femoral artery, and then descends along the inner edge of the vastus internus muscle, to which it distributes ramifications. In this case, we find at the most normal place of its origin, a small artery, which is sometimes a branch of a common trunk of the articular arteries, and sometimes arises directly from the popliteal artery, and anastomoses with the superior internal articular artery. When the origin of the latter is placed low, it goes a little from above downward, like the external, before it proceeds inward and forward. It divides into one or several muscular branches, which go to the lower part of the vastus internus muscle ; another median artery is situated lower, and passes behind this muscle and the common tendon of the extensors of the thigh, goes into ihe inner condyle of the femur and to the inner part of the ligaments of the knee ; finally, a third, which is superficial ; this proceeds on the anterior face of the femoro-tibial articulation, directly under the skin, anastomoses below with the branches of the internal inferior articular artery, and outwardly and transversely with the transverse branch of the external superior articular artery.

Both the external and the internal superior articular arteries give off considerable and recurrent branches, which communicate with the branches of the deep and superficial femoral arteries.

§ 1504. The middle articular artery (A. articulons genu media azijgos ) very rarely forms a distinct trunk, and is generally given oft' by the external superior articular artery. It goes forward and downward, penetrates from behind forward between the two condyles of the femur, and is distributed near the centre of the knee, in the femorotibial articulation, to the crucial ligaments, to the articular fat, to the posterior and middle part of the capsular ligament, and anastomoses with the branches of the inferior and also of the other two s uperior articular arteries.

§ 1505. Some small external and internal ramifications arise from the middle and inferior part of the popliteal artery and of its crural portion ; these are not constant and go to the lower part of the flexor muscles of the tibia and fibula. This portion then gives off the arteries of the gastrocnemii muscles and the inferior articular arteries.

§ 1506. The arteries of the gastrocnemii muscles (A. gemellce) usually arise, at least in part, above the inferior articular arteries and come from the posterior side of the popliteal artery. They are generally two, an external and an intentai, one for each of the two upper heads of the triceps suræ muscle. They rarely arise opposite each other. We frequently find also several other smaller gemellæ arteries, which however do not always exist. These vessels furnish the blood to the plantaris muscle, which however sometimes receives a proper and distinct branch.

§ 1507. The inferior articular arteries {A. articular es genu inferiores externa et interna) are usually two, an external and an internal, which generally form two distinct trunks. They arise from the anterior and lateral side of the popliteal artery, rarely at the same height. Sometimes one and sometimes the other is higher. Generally they are of the same size.

§ 1508. The external sends branches to the lower and middle head of the triceps suræ muscle. These branches however sometimes arise, at least in part, from a special branch of the popliteal artery. The artery then, passing directly above the external head of the tibia, below' the external lateral ligament of the knee, and on the capsular ligament of the articulation, goes thus from behind forward In its course it gives branches to the articular capsule, and anastomoses on one side by ascending lateral branches with the descending branches of the external superior articular artery, on the other by a large transverse branch, which passes above the lower part of the anterior face of the tendon of the extensors of the thigh, below the patella, with a similar transverse branch from the internal inferior articular artery.

§ 1509. The internal usually proceeds a little downward, goes from behind forward and from without inward, below the internal head of the triceps suræ muscle, directly surrounds the inner condyle of the tibia, gives numerous branches to the popliteus muscle, sends downward other branches, which anastomose on the internal face of the tibia with the recurrent branches of the posterior tibial artery, gives also others, which are larger and transverse, which communicate directly above the insertion of the common tendon of the extensors of the thigh with the recurrent branches of the anterior tibial artery, and finally goes upward and forward on the external anterior face of the ligament of the patella, where it anastomoses by several ramifications with the internal superior and with the external inferior articular arteries.

§1510. Besides these two inferior articular arteries, we sometimes find a middle articular artery (A. articularis inferior media, s. azygos ), which however arises oftener from the internal, and which penetrates from behind forward in the fernoro-tibial articulation, on the median line, between the two condyles of the tibia.

The popliteal artery generally gives off no other branches than those which have been described ; it is then the principal source of the anastomotic articular branches, by which, from the communication established between the upper and the posterior branches of the deep femoral artery, or between the inferior and recurrent branches of the arteries of the knee, the circulation of the blood may continue regularly in the leg, even when the superficial femoral and the popliteal arteries are obliterated. Thus these vessels are very much dilated after an operation for popliteal aneurism, where the superficial femoral and the popliteal arteries are obliterated.

4. Arteries of the Leg

§ 1511. The popliteal artery generally, after passing an inch without giving off any branches except those which go from its lower part into the soleus or to the third head of the triceps, suræ muscle, divides about an inch below the knee, very rarely higher and opposite the articulation, into two branches, called the tibial arteries (A. tibiales, s. cnemiales, Barclay). Of these two branches, the posterior is the larger, and may be considered from its direction as the continuation of the trunk, and is the common trunk of the posterior tibial and peroneal arteries ; the anterior is smaller, separates from the trunk, and is the anterior tibial artery. The common posterior trunk is always large! than the anterior ; sometimes it exceeds it greatly in size, in which case the latter is arrested in the middle of the leg, and all the branches which it generally gives off then arise from the posterior tibial and from the peroneal artery.

It sometimes divides very high. Thus, in a case observed by Sandifort, (1) the crural artery divided directly below Poupart’s ligament. Portal(2) has also found it to divide higher than usual. Ramsay(3) has seen it bifurcate, not in fact above the knee, but at least above the popliteus muscle ; the anterior tibial artery passed before this muscle, between it and the tibia, and was there compressed by him.

I. ANTERIOR TIBIAL ARTERY.

§ 1512. The anterior tibial artery (A. tibialis antica, s. rotularis)( 4) describes a slightly acute angle to go forward above the upper edge of the interosseous membrane. On the anterior face of the leg it divides into two branches, the smaller of which is the ascending or recurrent branch ; the other is the continuation of the trunk ; the latter descends on the anterior face of the limb and is distributed on the tibial side of the leg and foot.

§ 1513. The recurrent artery {A. recurrens ' gives branches to the tibialis posticus muscle, and is situated directly on the outer face of the upper extremity of the tibia ; it proceeds from below upward, to be distributed partly in the head of the tibia, partly also to the external and lower part of the ligaments of the knee and the common tendon of the extensor muscles of the leg. It anastomoses with the inferior articular artery, and by means of it with the superior and likewise with the ramifications of the femoral artery. We must place it among the accessory vessels of the lower extremity.

§ 1514. The trunk of the anterior tibial artery descends on the anterior face of the interosseous membrane, between the peroneus brevis muscle, the extensor digitorum communis longus, and the extensor longus pollicis proprius, and is covered by the two latter. It gives outward and inward numerous short and small branches, some of which are distributed in these muscles, while others pass through them to go into the peronei muscles and even to the skin.

(1) Obs. anat. path., book iv. p. 97. The crural artery divides thereinto an anterior and posterior tibial artery, and we cannot admit that there is any doubt in regard to its high division into a superficial and a deep crural artery, since Sandifort expressly says, that on the left side the division occurred as usual in the calf of the leg.

(2) Anat. méd., vol. iv. p. 230.

(3) Account of an unusual conformation of some muscles and vessels ; in the Edinb. Med. Journ., vol. viii. p. 283.— Barclay, loc. cit., p 263.

(4) We describe this artery first, although from its direction and its small size it ie not the continuation of the trunk, because it corresponds to the radial artery in its distribution.

When the posterior tibial or the peroneal artery is unusually large the anterior tibial artery terminates on the back of the foot or in the leg! Sometimes it does not exist as a separate trunk, and is replaced in the leg by the perforating branches of the posterior tibial artery and on the back of the foot by the peroneal artery. In some subjects also it is obliterated at the articulation of the foot, while above and below this part it admits the blood and is distributed as usual.(l) It generally furnishes the dorsal arteries of the foot and those of the large toe.

Near the lower end of the leg, it gives off the two malleolar arteries (A. malleolar es), an external and an internal, w r hich vary much in their size and place of origin.

§ 15.1 5. The external malleolar artery {A. malleolaris externa ) often arises a little higher than the internal, then descends from behind forward between the tibia and the fibula, resting directly on these bones and below the tendon of the peronei muscles, goes outward, expands on and in the external malleolus, frequently sends branches also to the anterior part of the lower end of the tibia, gives ramifications to the extensor hallucis brevis and abductor minimi digiti muscles, and anastomoses by a large branch with the recurrent branches of the tarsal artery on the anterior face of the articulation of the foot, and also with the anterior branches of the peroneal artery on the outside of the os calcis. This branch is constant, but it varies in size, and when large it partially or wholly gives off the dorsal artery of the foot. Sometimes it does not arise from the anterior tibial but from the peroneal artery, when the latter is unusually large. It is rarely given off by the peroneal artery, and arises still less frequently from the posterior tibial artery.

§ 1516. The internal malleolar artery (A. malleolaris interna) usually arises a little below the preceding. It not unfrequently divides into several branches, which are given off from the anterior tibial artery, one on the tibia and the other on the tibio-tarsal articulation.

It proceeds from without inward, under the tendons of the tibialis anticus and the extensor digitorum longus muscles, resting directly on the tibia and in the second case on the capsular ligament, arrives at the internal malleolus, distributes branches to this eminence, to the capsule of the articulation of the foot, to the astragalus, and anastomoses with the branches of the tarsal and posterior tibial arteries.

When two internal malleolar arteries exist, they communicate with each other.

This artery also sometimes arises, but more rarely than the preceding, from the peroneal or the posterior tibial artery.

§ 1517. After giving off the malleolar arteries, the trunk of the anterior tibial artery passes under the tendons of the extensor digitorum communis longus, on the outside of the extensor hallucis proprius, and comes on the back of the foot, giving off right and left small branches, which go into the periosteum, the dorsal ligaments of the tarsus, and the tendons of the extensor and peroneus brevis muscles. In this place it is called the dorsal artery of the foot (A. pediœa). The latter is rarely the continuation of the trunk of the peroneal or of the posterior tibial artery.

(1) This arrangement does not necessarily arise from the primary formation ; it. may, as Burns correctly remarks (or Barclay, toe. cit., p. 293), t e accidental and ho produced by compression. This ougnt also to be admitted in the second case

§ 1518. Internal and external branches arise from the dorsal artery of the foot. The latter are more numerous, larger, and more constant than the internal. We observe two particularly, the tarsal and the metatarsal artery.

The tarsal artery (A. tarsea ) arises from the outside of the dorsal artery of the foot, sometimes higher and sometimes lower on the back of the foot, even above the lower extremity of the tibia, in which case the external malleolar artery is very small ; this vessel is considerable, and its caliber almost equals that of the continuation of the trunk of the anterior tibial artery ; thus it would be more convenient to term it the external tarsal artery {A. tarsea externa ), in opposition to another branch which corresponds to the inside.

This tarsal artery goes transversely outward on the astragalus and os calcis, gives branches to these bones and also to the external part of the ligaments of the tibio-tarsal articulation and to the tarsus, sends off toward the external malleolus a large branch which anastomoses with the external malleolar artery (§ 1515), communicates on the outside of the os calcis with the branches of the peroneal artery, gives off forward other branches which unite to those of the metatarsal artery, penetrates to the cuboid bone, to the posterior extremity of the fifth metatarsal bone, anastomoses also with the external plantar artery on the outer edge of the foot, and distributes branches to the extensor digitorum brevis and to the abductor minimi digiti muscles.

§ 1519. Next comes the metatarsal artery (A. metatar sea ), which also arises from the outside of the dorsal artery of the foot, and varies so much in regard to its origin that it is sometimes a branch of the tarsal artery, and sometimes arises several inches distant from it, and from the dorsal artery of the foot, directly behind the anterior edge of the tarsus.

It is generally smaller than the preceding. Its direction, like that, is from within outward, assuming a course more transverse as it arises farther forward, and is always situated below the extensor digitorum brevis muscle. It is more or less evidently convex forward, and forms an arch, which is completed outwardly by the anastomosis constantly existing between it and the tarsal artery. This arch, on the outer edge of the tarsus, is changed by the smaller but constant branches of the tarsal artery into a vascular net-work, which covers most of the back of the foot. When this artery arises far backward, we usually find a second, which is smaller and proceeds on the anterior edge of the dorsal face of the tarsus, and which communicate with the posterior by very analogous longitudinal branches, which correspond in number and situation to the three external interosseous spaces. This second artery is not so much a branch of the dorsal artery of the foot as the result of anastomoses between these longitudinal branches and the dorsal interosseous arteries.

Sometimes there are even three metatarsal arteries, a third existing between the two we have mentioned.

A transverse arch, the convexity of which looks forward, constantly forms on the anterior part of the dorsal face of the tarsus or on the posterior part of the metatarsus. This arch contributes more or less but constantly with the posterior perforating arteries given off by the inferior tibial artery to form the dorsal interosseous arteries (A. interosseœ dorsales),

This vascular net-work is termed the dorsal arch of the tarsus (Æ. dorsalis tarseus). It varies much in extent and complexity.

A dorsal interosseous artery proceeds in each space between two metatarsal bones. These arteries are always very large and sometimes of an enormous caliber. They are four in number ; but the first or the most internal, comprised between the first and second metatarsal bones, is considered as the continuation of the trunk and is called very improperly the external dorsal artery of the large toe (A. hallucis dorsalis).

All these dorsal interosseous arteries are similar in the following respects :

1st. They anastomose by their posterior extremity with the posterior perforating arteries.

2d. They communicate with the anterior perforating arteries by their anterior extremity, between the bases of the first phalanges of the toes,

3d. They give off, outward and inward, branches, by which they anastomose with each other on the back of the tarsus, and which are distributed in the external interosseous muscles, the bones of the metatarsus, the abductor pollicis longus, and the skin of the dorsal face of the tarsus and of the toes. The branches which go to the toes, each of which receives at least two, the tibial and the peroneal , are called the dorsal arteries of the toes {A. digitales dorsales tibiales et peroneœ)

These superior interosseous arteries sometimes divide anteriorly into two branches, the tibial and the peroneal , each of which always goes to a different toe.

From the outer part of the tarsal arch a branch usually arises, which is also connected with the superior interosseous arteries, but which goes to the abductor minimi digiti muscle, and sometimes arises from the fourth interosseous artery, or, according to the usual way of numbering them, from the third. This last also most generally gives off another branch to the fibular side of the little toe, the dorsal peroneal branch of this appendage, while itself gives off the dorsal tibial branch.

Sometimes butrarely the second superior interosseous artery, generally called the first, does not arise from the metatarsal artery, but from the continuation of the trunk of the dorsal artery of the foot, and then the latter corresponds more than usual to the middle of the dorsal face of ♦he tarsus.

§ 1520. The internal branches of the dorsal artery of the foot are smaller than the external. They are generally as numerous, but usually there is only one very large. That arises about the centre of the tarsus, a little before the anterior extremity of the astragalus. It is well called the internal tarsal artery {A. tarsea interna).

This artery proceeds obliquely from without inward and from behind forward, distributes branches to the internal half of the bones of the tarsus and also to the first metatarsal bone, to part of the extensor digitorum brevis and of the abductor pollicis pedis, and anastomoses with the dorsal artery of the back of the foot on the dorsa.1 face of the tarsus, with the first interosseous artery, with the internal plantar artery on the inner edge of the foot, finally with the internal malleolar artery, and thus contributes to form the dorsal arch of the tarsus.

§ 1521. The trunk of the dorsal artery of the foot divides, between the posterior extremities of the first and second metatarsal bones, into two branches : one is the continuation of the trunk, the first metatarsal artery, usually termed the dorsal artery of the great toe {A. dorsalis hallucis) ; the second, the deep anastomosing branch (R. anastomoticus profundus ), passes directly to the sole of the foot, between the two bones, and forms with the external plantar artery the deep plantar arch {A. plantaris profundus), whence arise most of the plantar arteries of the toes (A. digitales plantares).

The dorsal artery of the large toe usually proceeds from behind forward on the back of the foot, along the external edge of the toe, and there divides into two branches, which become, one the common dorsal artery of the large toe , the other the dorsal tibial branch of the second toe.

It anastomoses most generally either at its place of origin or by one of its two branches with the plantar artery of the large toe.

II. POSTERIOR TIBIO-PERONEAL ARTERY.

§ 1522. The common trunk of the posterior tibial and peroneal artery, called also the tibio-peroneal artery, or simply the posterior tibial artery (A. tibio-peronea, s. tibialis postica, s. tibialis poplitea), descends vertically behind the interosseous membrane, covered by the heads of the peronei muscles, and generally, soon after the origin of the anterior tibial artery, g'ives off two considerable branches, an external and an internal.

The internal branch sends off small twigs to the popliteus muscle, penetrates principally into the tibia as the upper nutritious artery {A. nutritia tibiae superior ), and gives off from behind forward, into the periosteum of this bone, ramifications which anastomose on its internal face with those of the inferior and internal articular artery (§ 1509).

The external branch gives off ramuscules to the lower or middle head of the triceps surse muscle, proceeds below it, around the upper extremity of the fibula, sends off ramifications to the upper part of the peroneus longus muscle, and anastomoses both with the anterior tibial (§ 1511) and with the descending branches of the external inferior articular artery. These two branches consequently contribute to enlarge the system of the accessory vessels of the leg.

§ 1523. After giving them off, the tibio-peroneal trunk, which sends only inconstant branches to the soleus muscle, divides generally from one to two inches below the origin of the anterior tibial artery into two branches, the peroneal artery and the posterior tibial artery.

I. rERONEAL ARTERY.

§ 1524. The peroneal artery ( A . peronœa , s. fibularis) generally but not always arises at the place mentioned. Sometimes, but much more rarely, and only when the popliteal artery divides unusually high, it arises above, more frequently below, this point, and in the second case it is smaller in proportion as its origin is lower. Sometimes, in fact often, it does not exist, and it is replaced by the branches which are successively given off from the posterior tibial artery. Independently of its point of origin it varies very much in respect to its volume, a circumstance in regard to which it increases and diminishes inversely with the anterior tibial artery. It is generally smaller than the two tibial arteries ; but sometimes when one of the latter is deficient it is much larger than usual.

It descends on the posterior face of the interosseous ligament, covered by the soleus muscle, on the inside of the flexor longus digitorum communis muscle, gives its largest branches to these two muscles and also to the peronei, usually sends off, near the lower extremity of the leg, rather a large branch, which, passing under the posterior tibial artery, is called the posterior internal malleolar artery (A. malleolaris interna posterior ) and goes to the internal malleolus, on the surface of which it frequently communicates with the anterior internal malleolar artery furnished by the anterior tibial artery (§ 1516), and terminates on the outer face and the tuberosity of the os calcis by ramuscules, which enter partly into this bone, and partly by large branches by which it anastomoses with the posterior tibial artery, thus forming the inferior plantar arch.

§ 1525. At various heights of the leg, but generally toward its lower extremity, it gives off a branch which also varies much in size and which goes to the anterior face of the limb, passing between the two bones. When this branch is considerable it is termed the anterior peroneal artery ( A . peronœa anterior). It proceeds, near the surface, on the outer and anterior face of the leg, frequently descends to the external face of the tarsus, unites to the external malleolar artery, given off by the anterior tibial (§ 1515), concurs to form the dorsal arch of the tarsus, anastomoses with the branches of the external plantar artery, and distributes twigs to the tendons of the extensor digitorum communis, to the posterior part of the extensor minimi digiti muscle, to the external malleolus, to the astragalus, and to the cuboid bone.

This branch does not always arise from the peroneal artery ; it is then generally very small, and does not descend to the lower extremity of the leg or is entirely deficient. It is normally replaced by a branch of the anterior tibial given off by the external malleolar artery (§ 1515) less frequently, although more commonly than when it arises from the peroneal artery, it comes from the posterior tibial artery, and then it passes, attheusual place, on the anterior face of the leg.

The anterior peroneal artery much more rarely not only arises higher than usual, sometimes even not far from the middle of the anterior face of the leg, so that it sends off in this place ramifications to the peronei and to the extensor digitorum communis muscle, but it is also so large that it gives off the external malleolar artery ; and the dorsal artery of the foot is even the continuation of its trunk, and then the anterior tibial artery is very small, terminates on the back of the tarsus, and anastomoses with it.

Not more frequently the peroneal artery, extends farther than usual in the sole of the foot, and gives off the external and the internal plantar arteries. We have before us only one specimen of this anomaly. At the same time the anterior tibial artery is extremely small ; it stops at the middle of the leg, and all the branches it generally gives off below this point arise from the posterior tibial artery, which passes to the anterior face of the limb, about the level of its lower fourth.

II. POSTERIOR TIBIAL ARTERY.

§ 1526, The •posterior tibial artery (A. tibialis postica) is generally much larger than the peroneal artery, but its direction varies more than that of the primitive trunk, and it proceeds slightly inward.. It is generally a little larger than the anterior tibial artery and sometimes very much exceeds it in size. It descends, covered above by the third head of the triceps suræ muscle, between this muscle, the flexor longus digitorum communis and the tibialis posticus, and is entirely loose at its lower part, being covered only by the crural aponeurosis and the skin and the posterior face of the tibia, on the inside of the tendo-Achillis. In its course it gives off posteriorly numerous small branches to the soleus muscle and the tendo-Achillis, and anteriorly to the tibialis posticus on flexor longus digitorum communis muscles. At the lower part of the leg it sends off several larger branches both outward and inward ; these anastomose frequently, on the two malleoli, with the internal and external malleolar arteries, given off by the anterior tibial artery.

Theposterior tibial artery, proceedingbetween the tendons of the flexor longus digitorum communis and the tibialis posticus muscles, situated on its inside, and that of the extensor pollicis pedis on the outside, so that it passes on the latter, leaves the posterior face of the leg, and arrives at the sole of the foot, where it is situated on the posterior face of the os calcis.

Very rarely it passes from the posterior to the anterior face of the leg. thus becoming the dorsal artery of the foot. It most generally sends off, at the place where it enters the sole of the foot, a considerable branch, which goes into the os calcis and also into the lower extremity of the tendo-Achillis ; this branch anastomoses on the tubercle of the os calcis, before this tendon, with the final branches of the peroneal artery, and by means of them with the external malleolar artery ; thus a vascular plexus is formed which may be termed the inferior or plantar tarsal arch ( rete , s. arcus tarsus plantaris).

Not unfrequently another external and large branch goes to the posterior part of the abductor pollicis pedis muscle.

The posterior tibial artery then divides below the internal malleolus, about the centre of the inner face of the calcanéum, but a little behind it, into two branches, the external and internal plantar arteries.

These two branches, and the two branches described previously, very rarely arise from the peroneal artery, which happens when the posterior tibial arterv replaces the lower portion of the anterior tibial artery (§ 1525).

III. PLANTAR ARTERIES.

I. INTERNAL PLANTAR ARTERY.

§ 1 527. The internal plantar artery (A. plantaris interna ) is always smaller than the external, and vanes in size less than the latter. It follows the direction of the trunk and goes forward, under the tendons of the flexor digitorum longus muscle, above the long head of the abductor pollicis, not far from the inner edge of the foot. In its course it sends superficial branches to the abductors and the flexor pollicis brevis, and to the flexor communis digitorum brevis, gives deep branches to the inner half of the plantar face of the ligamentous envelop of the tarsus, to the os calcis, to the astragalus, and to the scaphoid bone ; anastomoses, in several places above the inner edge of the foot, with the branches of the internal artery of the tarsus and of the dorsal artery of the foot, and gives off anteriorly, between the first and second toes, generally one, often also two, branches, which form the plantar artery of the large toe, and frequently anastomoses, by an external branch, with the deep plantar arch.

II. EXTERNAL PLANTAR ARTERY.

§ 1528. The external plantar artery (A. plantaris externa) is deeper than the internal. It varies in size more than this latter. It is often scarcely visible, and again is sometimes three times the size of the internal. These differences depend principally on those in the size of the dorsal artery of the foot (§ 1517), for there is always an inverse relation between the caliber of these two vessels.

The external plantar artery immediately goes far outward. It proceeds between the abductor pollicis pedis and the flexor digitorum brevis below, and the accessory muscle above, toward the outer edge of the sole of the foot, where it extends forward, on the inner edge of the abductor minimi digiti muscle, gives branches to all the muscles mentioned, and anastomoses, by several branches which reascend above the outer edge of the foot, with the arteries of the tarsus and metatarsus.

At the posterior extremity of the fifth metatarsal bone it goes inward, and gives off, either in this place or a little before, a considerable branch, the peroneal plantar artery of the fifth toe (À. digitalis plantaris peronea digiti quinti ), which goes forward on the flexor minimi digiti muscle, along the fibular edge of the toes to the anterior extremity, sends branches to its flexor muscle, to the third internal interosseous muscle and to the skin, and finally anastomoses, on the ungueal phalanx of the little toe, with the tibial branch.

The deep or internal plantar artery then goes almost transversely forward and inward, between the internal interossei and the other muscles of the sole of the foot, and anastomosing with the deep anastomotic branch of the dorsal artery of the foot, between the first and second metatarsal bones, forms the deep plantar arch , which is concave backward and convex forward, and is situated very deeply on the posterior extremities of the metatarsal bones.

III. PLANTAR ARCH.

§ 1529. The digital arteries and the anterior and posterior perforating arteries arise from the deep palmar arch.

a. Digital arteries.

§ 1530. The digital arteries (Jl. digitales) arise forward, from the convex part of the arch.

Their general characters are,

a. They are situated deeply in the sole of the foot, and proceed from behind forward, on the square belly of the flexor digitorum longus communis, and the transverse belly of the adductor hallucis.

b. Between the posterior extremities of the toes they divide into two branches, which go one to the tibial side of the outer, the other to the peroneal side of the inner toe.

c. The two branches unite on the ungueal phalanx, and also anastomose with each other and with the dorsal branches.

d. They anastomose forward with the superior and inferior metatarsal arteries at their bifurcation.

But they differ very much in regard to their origin. The deep arch most generally gives rise to the deep plantar arteries of the three outer and the peroneal branch of the second toe, less frequently to the tibial branch of this and the plantar branch of the large toe.

The peroneal branch of the little toe often comes directly from the plantar arch, and even farther behind it, from the external plantar artery (§ 1528), but it not unfrequently arises, by a common trunk, with the tibial branch of the fifth toe and the peroneal branch of the fourth. We have never observed that when this first digital artery gave off also the tibial branch, it was destined solely for the fifth toe, and did not proceed at the same time to the peroneal side of the fourth. Even when the peroneal branch of the fifth toe forms a distinct and separate trunk, it generally communicates by large anastomosing branches, both on the metatarsus and on the first phalanx of the toe, with the second digital artery, and the tibial branch of the fifth toe.

The second digilcd artery when it does not form a trunk with the preceding, goes to the tibial side of the fifth toe and to the peroneal side of the fourth.

Next comes the third, which goes to the tibial side of the fourth toe and to the fibular side of the third. Sometimes this artery is double as far as the arch from whence it arises to the anterior part of the metatarsus ; but its two trunks there unite in one, which soon divides into two branches, the tibial branch of the fourth and the peroneal branch of the third toe. This arrangement occurs particularly when the usual number of digital arteries is diminished in any manner whatever, as, for instance, by the union in one trunk of the peroneal branch of the fifth toe and of the two following branches.

Next comes usually a fourth, which divides in the same manner for the second and third toes.

The fifth constantly forms the tibial branch of the second toe. Sometimes, when the anterior tibial artery is much smaller and the posterior on the contrary is larger than usual, it forms the common plantar artery of the large toe , from whence the tibial branch of the second also arises.

The plantar artery of the large toe and the tibial branch of the second vary the most in their origin and arrangement.

This artery is generally the continuation and termination of the trunk of the dorsal artery of the foot, which comes to the first phalanx of the large toe, goes to its plantar face, and gives origin to all the plantar and dorsal branches of this toe, sending off first the peroneal dorsal branch, then the peroneal plantar branch, next the tibial plantar branch, and finally the tibial dorsal branch, which anastomose as usual.

More rarely the continuation of the trunk of the dorsal artery of the foot divides, soon after giving off the deep anastomosing branch to the sole of the foot, into two branches, a superior, which becomes the common trunk of the dorsal artery of the large toe and the tibial branch of the second ; an inferior, or the common trunk of the two plantar arteries of this toe, which bifurcates near the centre of the plantar face of the large toe, to give rise to two plantar branches. But we must remark that here we find a similarity between the anomaly and the normal or more common arrangement first described, since the two branches communicate at the base of the first two toes by a large anastomosing branch.

The superficial internal plantar artery given off by the posterior tibial artery always contributes to form the two plantar branches of the large toe and the inner branch of the second; since it constantly anastomoses near the anterior extremity of the first metatarsal bone with the trunk of these branches, and thus forms the superficial plantar arch {arcus plantaris superficialis).

When the anterior tibial artery is smaller than usual, it sometimes but not always gives off only the dorsal artery of the large toe ; sometimes too it sends off in part the tibial artery of the second. On the contrary, the trunk from which the plantar branches of the large toe and the plantar branch of the second arise, the internal plantar artery, is unusually large, and is always increased by a branch, which varies in size ; this arises from the deep plantar arch, and communicates with it toward the extremity of the first metatarsal bone.

Finally, sometimes but rarely all the arteries of the first and second toe arise only from the posterior tibial artery, particularly from the deep arch. The anterior tibial artery, which is very small, then terminates simply by a deep anastomosing branch in the deep plantar arch, and a large branch arises from the latter, which soon divides into two : one is deeper and larger, and is the continuation of the trunk ; it goes from behind forward on the first metatarsal bone, and is also enlarged by one or two branches arising from the internal plantar artery, which is also in this case unusually large, and bifurcates to give rise to the common plantar artery of the large toe and also to the tibial artery of the second ; the other is smaller and more superficial, ascends to the back of the foot between the first two metatarsal bones, gives off the dorsal branches of the large toe, and becomes, with a second digital artery given off by the deep branch, the common trunk of the tibial branch of the third toe and of the peroneal branch of the second.

6. Anterior perforating arteries.

§ 1531. The anterior perforating arteries {A. perforantes anteriores ) arise on the anterior part of the deep plantar arch, sometimes between the digital arteries. They are small and go only to the interosseous muscles, to the transverse head of the adductor hallucis muscle, and the metatarsal bones. A part of its ramifications communicate anteriorly with the digital arteries and the dorsal artery of the foot.

c. Posterior perforating arteries.

§ 1532. The posterior perforating arteries {A. perforantes posteriores) arise from the posterior and upper surface of the deep plantar arch. They give branches to the posterior part of the interosseous muscles, and also recurrent branches to the anterior part of the tarsal ligaments and bones, and passing through the posterior extremities of the interosseous spaces, come on the back of the foot, where they anastomose with the upper interosseous arteries.

These arteries are generally small, and can be considered only as the anastomoses between the dorsal and plantar arches. However, as these latter and the dorsal interosseous arteries are generally much larger than their corresponding parts in the hand, the posterior perforating arteries are sometimes unusually developed ; so that the transverse tarsal artery sends only small anastomosing branches to their posterior extremities, in the place where they appear on the back of the foot. But in this case they are not the only origin of the dorsal interosseous arteries, which arise also from the plantar arteries of the toes and are much larger than the common trunks of the digital arteries, and which give all the digital branches commonly arising from the anterior side of the deep arch.

In this case the usual anterior branches of the plantar arch still exist, but they are merely branches for the deep muscles of the sole of the foot and the anterior perforating arteries ; so that they are as slightly developed as the dorsal interosseous arteries generally are.

There are many degrees between this state of the dorsal interosseous arteries and the common one ; so that for instance many or all the dorsal interosseous arteries contribute equally to form the digital arteries, and thus the dorsal and plantar arteries have about the same size, although it does not necessarily follow that the dorsal interosseous arteries arise from the deep plantar arch, as in the anomaly described. On the contrary, they sometimes become unusually large, but are however only the branches of the dorsal arch.

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Cite this page: Hill, M.A. (2024, April 19) Embryology Book - Handbook of Pathological Anatomy 2.8. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_Handbook_of_Pathological_Anatomy_2.8

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