Part 69

THE PALMAR ARCH AND ITS BRANCHES IN THE PALM OF THE HAND.

The interosseous muscles have been removed, except those of the third and fourth digits. 1, M. abductor digiti quinti; 2, 3, Mm. interossei of third and fourth digits; 4, M. adductor pollicis; 5, M. flexor brevis pollicis. a, termination of radial artery; b, palmar arch; c, A. princeps pollicis et indicis; d, Aa. interosseæ; e, muscular branches of the same; f, A. ulnaris; g, deep palmar branch of ulnar nerve.]

Branches of the cœliac artery:

1. =A. hepatica= (d).--The hepatic artery passes cranioventrad, pierces the descending limb of the great omentum and passes craniad to the liver, lying, together with the portal vein and common bile-duct, in the ventral boundary of the foramen epiploicum (foramen of Winslow) and contained, together with the last-named vessels, in a fibrous sheath called the capsule of Glisson. Just before entering the sheath it gives off the =gastroduodenalis= (g). At its termination the hepatic artery divides, sending branches to the lobes of the liver and a =cystic= artery to the gall-bladder.

a, abdominal aorta; b, A. cœliaca; c, A. mesenterica superior (cut); d, A. hepatica (cut); e, A. gastrica sinistra; f, A. lienalis; g, A. gastroduodenalis (cut from A. hepatica); h, A. pylorica; i, A. gastroepiploica dextra; j, A. pancreaticoduodenalis superior; k, A. pancreaticoduodenalis inferior (cut from inferior mesenteric); l, A. ventriculi dorsalis. 1, spleen; 2, stomach; 3, duodenum; 4, pancreas.]

a. =A. gastroduodenalis= (g).--This arises from the hepatic near the pylorus and passes caudad, dividing one or two centimeters from its origin into three branches, =A. pylorica= (h), =A. pancreaticoduodenalis superior= (j), and =A. gastroepiploica dextra= (i). The =pylorica= (h) (which may arise directly from the hepatic) passes to the pylorus, thence along the lesser curvature of the stomach, dividing into numerous branches and anastomosing with the gastrica sinistra. The =pancreaticoduodenalis superior= (j) passes to the duodenum, supplying it and the duodenal part of the pancreas and anastomosing with the pancreaticoduodenalis inferior (k). The =gastroepiploica dextra= (i) passes along the greater curvature of the stomach from the pyloric end and supplies the walls of the stomach, sending branches also to the ascending limb of the great omentum. These branches anastomose with the terminal branches of the splenic artery.

2. =A. gastrica sinistra= (e).--This arises from the cœliac artery and passes to the lesser curvature of the stomach, extending along this to the right. It gives off many branches to the walls of the stomach, and anastomoses with A. pylorica.

=A. ventriculi dorsalis= (l).--One or two small arteries which arise either from the gastrica sinistra or the cœliac artery, and pass toward the dorsal part of the greater curvature of the stomach near its cardiac end.

3. =A. lienalis= (f).--The splenic artery is the largest of the branches of the cœliac axis, of which it appears to be the direct continuation. It divides into two large branches, one to the cranial end, the other to the caudal end, of the spleen (1). From the latter a large branch passes to the pancreas and descending limb of the great omentum.

B. =A. mesenterica superior= (Fig. 126, d).--The superior mesenteric artery is larger than the cœliac. It supplies the blood to the small intestines and caudal portion of the pancreas and to the ascending and transverse colon. It arises from the ventral side of the abdominal aorta about one centimeter caudad of the cœliac axis and passes caudoventrad, forming a curve with the convexity dextrad. It gives off the =pancreaticoduodenalis inferior=, =colica media=, =colica dextra=, =ileocolica=, and numerous branches to the small intestine.

1. =A. pancreaticoduodenalis inferior= (Fig. 125, k).--This passes to the caudal end of the pancreas and a part of the duodenum, anastomosing with the pancreaticoduodenalis superior.

2. =A. colica media= is a large branch to the transverse and descending portions of the large intestine. It divides and sends branches in both directions which anastomose with the colica dextra and with branches from the inferior mesenteric arteries.

3. =A. colica dextra.=--A small branch which passes to the ascending and transverse colon, anastomosing with the colica media and ileocolica. It is sometimes absent.

4. =A. ileocolica.=--This passes to the cæcum and supplies that structure, sending branches to the ileocolic valve and the caudal end of the ileum, and anastomosing with the colica dextra and the intestinal branches of the superior mesenteric.

5. The superior mesenteric now divides into about sixteen terminal branches which pass to the small intestine. In many cases these branches unite near the intestine, forming arches, and from these arches numerous short branches pass to the intestine.

3. =A. adrenolumbalis= (or =lumboabdominalis=) (Fig. 126, e).--This rises from the aorta, one on each side, about two centimeters caudad of the superior mesenteric. Each passes laterad onto the dorsal body wall, supplying the muscles of this region. A large branch passes caudad along the surface of the muscles dorsad of the kidney and anastomoses with the iliolumbar artery. From the adrenolumbalis rises usually:

=A. phrenica= (f).--The phrenic artery rises either from the cœliac (c) or the adrenolumbalis (e) and passes to the diaphragm, near its dorsal border. In the diaphragm it passes ventrad, lying at the medial margin of the costal portion of the diaphragm, as far as its sternal portion, where it unites with the artery of the opposite side. The two thus form an arch, from which radiating arteries pass off to supply the diaphragm.

4. =A. renalis= (g).--The two renal arteries arise from the sides of the aorta, usually at about the same point, so that the left passes caudolaterad and the right craniolaterad (owing to the position of the kidneys). The artery usually divides just before entering the kidney (2). It passes dorsad of the vein (t). The renal artery sometimes sends a branch to the suprarenal body (1). It also occasionally gives origin to the spermatic artery (h).

a, vena cava inferior; b, abdominal aorta; c, A. cœliaca (cut); d, A. mesenterica superior (cut); e, A. adrenolumbalis; f, A. phrenica; g, A. renalis; h, A. spermatica interna; i, A. mesenterica inferior (cut); j, A. iliolumbalis; k, A. iliaca externa; l, A. hypogastrica; m, beginning of A. femoralis; n, A. umbilicalis; o, A. and V. sacralis media (o, the artery; o′, the vein); p, A. glutea superior; q, A. glutea inferior; r, A. and V. hemorrhoidalis media; s, V. adrenolumbalis; t, V. renalis; u, V. spermatica interna; v, V. iliolumbalis; w, V. iliaca communis; x, V. femoralis; y, V. and A. profunda femoris; z, V. hypogastrica. 1, suprarenal body; 2, kidney; 3, ureter; 4, outline (broken) of rectum.]

5. =A. spermatica interna= (h).--This rises from the aorta on each side at about the level of the caudal ends of the kidneys, and passes laterad (or it may arise from the renal). In male specimens the artery turns caudad, along with the corresponding vein (u), and passes to the inguinal canal. Thence it passes along with the vas deferens and the vein (forming all together the spermatic cord) to the testes and the other structures in the scrotum.

In females (Fig. 112, 2, page 265) the artery is larger and passes more nearly directly laterad, being much convoluted. It passes to the ovary, being now called the =ovarian artery=. It sends branches into the ovary (c) and to the cranial end of the uterus (f); the latter anastomosing with branches of the uterine artery (3).

6. =A. mesenterica inferior= (Fig. 126, i).--The inferior mesenteric artery has its origin from the aorta at about the level of the last lumbar vertebra. It passes toward the large intestine, and near it divides into two branches, the =colica sinistra=, which passes craniad along the descending colon, anastomosing with the colica media, and the =superior hemorrhoidal=, which passes caudad along the descending colon and rectum and anastomoses with the middle hemorrhoidal (page 308).

7. =A. iliolumbalis= (Fig. 126, j).--The iliolumbar arteries arise from the aorta about two centimeters caudad of the inferior mesenteric and pass laterad over the ventral surface of the psoas minor and iliopsoas muscles. Each divides into two main branches, one passing caudad and the other craniad; these supply the muscles of this region. The cranial branch anastomoses with branches of the adrenolumbalis (e). The caudal branch sends an artery through the abdominal wall to appear at the cranial edge of the thigh; it passes onto the lateral surface of M. sartorius and extends here some distance distad.

8. =A. lumbalis.=--There are usually seven pairs of lumbar arteries, passing almost directly dorsad from the dorsal surface of the aorta; the first pair arising just craniad of the diaphragm, the last at the same level as the origin of the external iliac. The two arteries of a pair usually arise from the aorta one behind the other, or they may arise by a common trunk. They correspond to the intercostal arteries. They pass between the centra of the vertebræ and the muscles of the dorsal region, and send one main branch laterad, the other dorsad; both supply the dorsal muscles. From the dorsal branch small arteries pass into the vertebral canal to join the anterior spinal artery.

9. =A. iliaca externa= (Fig. 126, k).--The external iliac artery passes obliquely caudad from the aorta, lying ventrad of the common iliac vein and against the medial surface of the psoas minor muscle. It passes onto the ventral surface of this and the iliopsoas and at the same time reaches the tendon of the abdominal muscles; through a small opening in this tendon lying ventrocaudad of that for the iliopsoas, it leaves the abdominal cavity. On its emergence from the abdominal cavity onto the medial surface of the thigh it receives the name =A. femoralis= (m). The branches of the external iliac artery are described below (page 309).

10. =A. hypogastrica= (or iliaca interna) (Fig. 126, l).--The hypogastric or internal iliac arteries are given off from the aorta usually within a centimeter caudad of the external iliac. Each passes caudolaterad, lying on the medial side of the common iliac vein, and divides into branches which supply the structures within the pelvis and the muscles about the pelvic wall. There is much variation in the origin and relations of the branches of this artery. The following seems to be a very common arrangement: A very short distance from the origin the =umbilical= artery (n) is given off. The hypogastric artery then extends two or three centimeters and gives off =A. glutea superior= (p), which passes at once to the pelvic wall. A little farther caudad the hypogastric divides into the =middle hemorrhoidal= (r), to the rectum, and the =glutea inferior= (q), which passes out of the pelvis.

Branches of the hypogastric artery:

a. =A. umbilicalis= (Fig. 126, n).--This small artery arises from the hypogastric about one centimeter from the beginning of the latter, and passes ventrad to the bladder. Here it divides into two branches--the =superior vesical= to the sides of the bladder, the =inferior vesical= to the neck of the bladder and the urethra.