Part 195

i, Radial artery; j, ulnar artery; k, volar interosseous artery; l, deep volar arch; m, external (fifth) volar metacarpal artery; n, deep volar metacarpal arteries; p, superficial volar metacarpal arteries; o, q, common digital arteries; r, proper digital arteries. ]

The rete carpi dorsale gives off four =dorsal metacarpal arteries= which descend in the intermetacarpal spaces and unite near the metacarpo-phalangeal joints with the volar arteries to form the common digitals.

The =thoracic aorta= supplies the last nine or ten pairs of intercostal arteries, but no anterior phrenic arteries. It gives off two or more œsophageal branches, in addition to the broncho-œsophageal, which arises close to or with the sixth intercostal and ramifies in the usual manner.

The =abdominal aorta=, after giving off the external iliac arteries, continues about half an inch to an inch (ca. 1 to 3 cm.) under the last lumbar vertebræ, gives off the internal iliacs, and is continued by the middle sacral artery. This small vessel runs backward under the sacrum and coccygeal vertebræ and gives off branches in segmental fashion.

FIG. 491.—END BRANCHES OF AORTA AND RADICLES OF POSTERIOR VENA CAVA OF DOG.

a, Abdominal aorta; b, posterior mesenteric artery; c, lumbar arteries; d, circumflex iliac artery; e, external iliac artery; f, deep femoral artery; g, posterior abdominal artery; h, external pudic artery; a, femoral artery; i, i, internal iliac arteries; k, visceral branch of i; l, parietal branch of i; m, ilio-lumbar artery; n, anterior gluteal artery; o, lateral coccygeal artery, p, posterior gluteal artery; q, umbilical artery; r, middle hæmorrhoidal artery; β, posterior hæmorrhoidal artery; s, perineal artery; t, art. profunda penis; n, art. bulbi urethræ, v, art. dorsalis penis; w, middle sacral artery, a′, posterior vena cava; other veins are satellites of arteries and correspondingly named; 1, ilio-psoas muscle; 2, tendon of psoas minor; 3, abdominal muscles; 4, sartorius; 5, rectus femoris; 5′, vastus internus; 6, pectineus; 6′, adductor; 7, gracilis; 8, symphysis pelvis; 9, ilium; 10, pyriformis; 11, gluteus superficialis; 12, obturator internus; 13, penis; 14, lumbar vertebræ. (After Ellenberger, in Leisering’s Atlas.) ]

The =cœliac artery= gives off the hepatic artery and forms a short =gastro-splenic= trunk. The hepatic artery gives off several hepatic branches, and the pyloric or right gastric artery, which passes along the lesser curvature of the stomach, anastomoses with the (left) =gastric artery=, and is continued by the gastro-duodenal. This divides near the pylorus into right gastro-epiploic and pancreatico-duodenal. The (left) gastric artery passes to the lesser curvature of the stomach and ramifies chiefly on the left part of the stomach, giving off a branch which anastomoses with the pyloric branch of the hepatic. The =splenic artery= gives off pancreatic branches, and reaches the lower part of the spleen. It gives off the left gastro-epiploic, and a branch which passes to the dorsal end of the spleen, which it supplies, besides giving off twigs to the left extremity of the stomach.

The =anterior mesenteric artery= arises close behind the cœliac. It gives off a common trunk for two colic arteries and the ileo-cæco-colic. The former supply the transverse and the anterior part of the left or descending colon, while the latter divides into branches for the ileum, cæcum, and first part of the colon. The trunk is continued as the artery of the small intestine, giving off fourteen to sixteen branches (Aa. jejunales), which form a series of anastomotic arches in the mesentery near the bowel.

Two =phrenico-abdominal arteries= (Aa. phrenicæ caudales) come off from the aorta behind the anterior mesenteric, and divide into phrenic and abdominal branches. Each phrenic artery diverges from its fellow in descending on the abdominal surface of the corresponding crus of the diaphragm to the sternal part. The inner branches anastomose with those of the opposite artery, the outer branches with intercostal arteries chiefly. The abdominal arteries give branches to the lumbar muscles, the renal fat and capsules, and ramify in the oblique abdominal muscles.

The =renal= and =spermatic arteries= offer no special features.

The =utero-ovarian artery= divides near the ovary into three or four branches which supply the ovary and uterus, anastomosing with the uterine artery.

The =posterior mesenteric artery= is small. It divides into two branches which supply the terminal part of the colon and the anterior part of the rectum.

The =circumflex iliac artery= usually arises from the terminal part of the aorta.

The =external iliac artery= usually gives off no collateral branches.

FIG. 492.—ARTERIES OF PELVIC LIMB OF DOG, INTERNAL VIEW.

a, Abdominal aorta; b, femoral; c, c′, deep femoral; d, posterior abdominal; e, external pudic; f, internal circumflex; g, anterior femoral (accompanied by anterior branch of femoral nerve); h, external circumflex; i, k, muscular branches; l, articular branch; m, saphenous; n, o, plantar and dorsal branches of saphenous; q, saphenous nerve; r, obturator nerve; 1, ilio-psoas; 2, ilium; 3, gracilis; 4, semitendinosus; 5, adductor magnus; 6, adductor longus; 7, quadriceps femoris; 8, sartorius; 9, semimembranosus; 10, gastrocnemius; 11, tibialis anterior; 12, tibia. (Ellenberger-Baum, Anat. d. Hundes.) ]

FIG. 493.—ARTERIES OF DISTAL PART OF RIGHT HIND LIMB OF DOG, ANTERIOR VIEW.

a, External branch of anterior tibial artery; b, anterior tibial artery; c, saphenous artery (anterior branch); d, perforating metatarsal artery; e, dorsal metatarsal arteries; f, deep dorsal metatarsal arteries; g, superficial dorsal metatarsal arteries; h, anastomoses between dorsal and plantar arteries; i, common digital arteries; j, proper digital arteries. ]

FIG. 494.—ARTERIES OF DISTAL PART OF RIGHT HIND LIMB OF DOG, POSTERIOR VIEW.

k, Saphenous artery (posterior branch); l, l′, internal and external plantar arteries; m, perforating metatarsal artery; n, deep plantar metatarsal arteries; o, superficial plantar metatarsal arteries; p, common digital artery; q, proper digital arteries. ]

The =femoral artery= has the usual course. The deep femoral gives off the posterior abdominal and external pudic arteries by a very short common trunk or separately. In the female the external pudic divides into anterior and posterior branches; the former runs forward, supplies branches to the inguinal lymph glands, the mammary glands and skin, and anastomoses with the mammary branch of the internal thoracic artery; the posterior branch pursues a flexuous course between the thighs to the vulva, where its terminal branches anastomose with the internal pudic artery. The anterior femoral may arise by a short common trunk with the external circumflex. The former, accompanied by the anterior branch of the femoral nerve, dips in between the rectus femoris and vastus internus. The external circumflex artery passes forward between the sartorius internally and the rectus femoris and tensor fasciæ latæ externally and supplies branches to these muscles and the glutei. In addition to muscular branches of considerable size, an articular branch (A. genu suprema) arises a little below the middle of the thigh and runs downward and forward to the inner face of the stifle joint. The =saphenous artery= is large. It arises from the inner surface of the femoral a little below the middle of the femur, descends superficially to the upper part of the leg and divides into two branches. The smaller =anterior branch= (Ramus dorsalis) passes obliquely downward and forward across the inner surface of the tibia to the flexion surface of the hock and terminates in three =superficial dorsal metatarsal arteries=. The =posterior branch= (Ramus plantaris) passes down on the inner face of the gastrocnemius and the long digital flexor. It gives off a branch (A. tarsea lateralis) which descends obliquely to the external surface of the tarsus, and at the posterior face of the tarsus detaches the =internal= and =external plantar arteries=; these descend on either side of the deep flexor tendon and unite with the perforating metatarsal artery to form the proximal plantar arch. The artery continues down the middle of the plantar surface of the metatarsus and divides near the metacarpo-phalangeal joints into three =superficial plantar metatarsal arteries=. These vessels unite with three =deep plantar metatarsal arteries= which descend from the proximal plantar arch and with branches from the dorsal metatarsal arteries. From these anastomoses four digital arteries result; of these, the central two have a common digital trunk.

The =popliteal= and =posterior femoral arteries= present nothing of special interest.

The =posterior tibial artery= is small, being replaced largely by the saphenous. It supplies twigs to the flexor muscles at the upper part of the leg.

The =anterior tibial artery= descends on the anterior face of the tibia and tarsus and is continued as the perforating metatarsal artery, which passes through the upper part of the space between the second and third metatarsal bones and concurs with the plantar branches of the saphenous in the formation of the plantar arch. Besides muscular and articular branches, the anterior tibial supplies the external or fifth dorsal metatarsal artery for the outer side of the fifth digit. At the proximal part of the metatarsus it gives off three =deep dorsal metatarsal arteries= which descend in the intervals between the metatarsal bones and concur with the superficial dorsal and the plantar arteries in the formation of the =digital arteries=. The latter resemble in general arrangement the corresponding arteries of the thoracic limb.

The =internal iliac artery= (Fig. 491) runs backward and a little outward across the ilio-psoas, and on reaching the ilium divides into parietal and visceral branches. The =parietal branch= is the larger. It runs backward on the lateral wall of the pelvis, passes out through the lesser sciatic notch, and breaks up into branches which supply the muscles in this region like the posterior gluteal (or ischiatic) artery of the horse. It gives off the following branches: (1) The =ilio-lumbar artery= passes outward between the ilio-psoas and the shaft of the ilium and ramifies in the gluteus medius, giving branches to the ilio-psoas and tensor fasciæ latæ; it may arise from the internal iliac. (2) The =anterior gluteal artery= passes out behind the posterior superior spine of the ilium and supplies branches to the glutei. (3) =Muscular branches= go to the obturator internus, coccygeus, and retractor ani. (4) The =lateral coccygeal artery= (A. caudalis lateralis superficialis) passes back at first on the outer face of the coccygeus and continues beneath the skin along the side of the tail. The =visceral branch= or =internal pudic artery= passes back below the parietal branch on the lateral face of the rectum, retractor ani, and coccygeus. Its chief collateral branches are: (1) The =umbilical artery=, which pursues a flexuous course and supplies twigs to the bladder, ureter, and vas deferens. In the bitch it gives off a large =uterine artery= which ramifies chiefly in the body and neck of the uterus and the vagina and anastomoses with the utero-ovarian. (2) The =middle hæmorrhoidal artery= arises near the ischial arch, passes upward and forward on the lateral surface of the rectum, gains its dorsal surface and anastomoses with the posterior mesenteric; it supplies the rectum and the anus, together with its muscles and glands. (3) A small =perineal artery= is detached to the perineum. In the male the trunk turns around the ischial arch as the =artery of the penis= (A. penis). This vessel, after giving off the =deep artery of the penis= (A. profunda penis), which supplies the =artery of the bulb= (A. bulbi urethræ) and enters the corpus cavernosum, is continued as the =dorsal artery of the penis= (A. dorsalis penis) along the dorsum penis. In the female the terminal branches of the trunk go to the vulva, vestibular bulb, and clitoris.

THE VEINS

The arrangement of the veins is, of course, correlated in general with the arterial system, but a few special features are worthy of mention.

The =anterior vena cava= is formed by the junction of short right and =left brachiocephalic= (or subclavian) =veins=, and each of the latter results from the confluence of =jugular= and =brachial veins=.