ANGIOLOGY 





The right common iliac artery (Fig. 539) is somewhat longer than the left, and 

 passes more obliquely across the body of the last lumbar vertebra, hi front of 

 it are the peritoneum, the small intestines, branches of the sympathetic nerves, 

 and, at its point of division, the ureter. Behind, it is separated from the bodies of 

 the fourth and fifth lumbar vertebrae, and the intervening fibrocartilage, by the 

 terminations of the two common iliac veins and the commencement of the inferior 

 vena cava. Laterally, it is in relation, above, with the inferior vena cava and the 

 right common iliac vein; and, below, with the Psoas major. Medial to it, above, 

 is the left common iliac vein. 



The left common iliac artery is in relation, in front, with the peritoneum, the 

 small intestines, branches of the sympathetic nerves, and the superior hemorrhoidal 

 artery; and is crossed at its point of bifurcation by the ureter. It rests on the 

 bodies of the fourth and fifth lumbar vertebras, and the intervening fibrocartilage. 

 The left common iliac vein lies partly medial to, and partly behind the artery; 

 laterally, the artery is in relation with the Psoas major. 



Branches. The common iliac arteries give off small branches to the peritoneum, 

 Psoas major, ureters, and the surrounding areolar tissue, and occasionally give 

 origin to the iliolumbar, or accessory renal arteries. 



Peculiarities. The point of origin varies according to the bifurcation of the aorta. In three- 

 fourths of a large number of cases, the aorta bifurcated either upon the fourth lumbar vertebra, 

 or upon the fibrocartilage between it and the fifth; the bifurcation being, in one case out of nine, 

 below, and in one out of eleven, above this point. In about 80 per cent, of the cases the aorta 

 bifurcated within 1.25 cm. above or below the level of the crest of the ilium; more frequently 

 below than above. 



The point of division is subject to great variety. In two-thirds of a large number of cases it 

 was between the last lumbar vertebra and the upper border of the sacrum; being above that point 

 in one case out of eight, and below it in one case out of six. The left common iliac artery divides 

 lower down more frequently than the right. 



The relative lengths, also, of the two common iliac arteries vary. The right common iliac was 

 the longer in sixty-three cases; the left in fifty-two; while they were equal in fifty-three. The 

 length of the arteries varied, in five-sevenths of the cases examined, from 3.5 to 7.5 cm.; in about 

 half of the remaining cases the artery was longer, and in the other half, shorter; the minimum 

 length being less than 1.25 cm., the maximum, 11 cm. In rare instances, the right common 

 iliac has been found wanting, the external iliac and hypogastric arising directly from the aorta. 



Collateral Circulation. The principal agents in carrying on the collateral circulation after the 

 application of a ligature to the common iliac are: the anastomoses of the hemorrhoidal branches 

 of the hypogastric with the superior hemorrhoidal from the inferior mesenteric; of the uterine, 

 ovarian, and vesical arteries of the opposite sides; of the lateral sacral with the middle sacral 

 artery; of the inferior epigastric with the internal mammary, inferior intercostal, and lumbar 

 arteries; of the deep iliac circumflex with the lumbar arteries; of the iliolumbar with the last 

 lumbar artery; of the obturator artery, by means of its pubic branch, with the vessel of the 

 opposite side and with the inferior epigastric. 



The Hypogastric Artery (A. Hypogastrica ; Internal Iliac Artery) (Fig. 539). 



The hypogastric artery supplies the walls and viscera of the pelvis, the buttock, 

 the generative organs, and the medial side of the thigh. It is a short, thick vessel, 

 smaller than the external iliac, and about 4 cm. in length. It arises at the bifur- 

 cation of the common iliac, opposite the lumbosacral articulation, and, passing 

 downward to the upper margin of the greater sciatic foramen, divides into two 

 large trunks, an anterior and a posterior. 



Relations. It is in relation in front with the ureter; behind, with the internal iliac vein, the 

 lumbosacral trunk, and the Piriformis muscle; laterally, near its origin, with the external iliac 

 vein, which lies between it and the Psoas major muscle; lower down, with the obturator nerve. 



In the fetus, the hypogastric artery is twice as large as the external iliac, and is 

 the direct continuation of the common iliac. It ascends along the side of the 

 bladder, and runs upward on the back of the anterior wall of the abdomen to the 

 umbilicus, converging toward its fellow of the opposite side. Having passed through 



