VISCERAL BRANCHES OF THE ABDOMINAL AORTA. Wom 
ing lumbo-sacral articulation by becoming the internal iliac artery; at the same 
time it gives off the external iliac artery to the lower extremity. 
The direction of each common iliac is well indicated by a line drawn from the 
bifurcation of the aorta to a point midway between the symphysis pubes and the 
anterior superior spine of the ilum. 
The’ angle included between the two diverging trunks is about 60° in the male 
and about 68° in the female. 
The right artery is, for obvious reasons, a little longer than the left; the former 
is about two inches, and the latter one and three-quarter inches in length. 
Relations.—Anterior.—Both arteries are covered by peritoneum, and are separated 
by it from coils of the small intestine. Communicating branches between the aortic and 
hypogastric plexuses of the sympathetic pass in front of the arteries, each of which is also 
crossed near its termination by the corresponding ureter. 
The left artery is in addition crossed in front by the superior hemorrhoidal vessels. 
Posterior.—Behind the artery of each side are the bodies of the fourth and fifth lumbar 
vertebrae, with the intervertebral disc above and below the latter, the psoas muscle, and 
the sympathetic cord. These relationships, however, are much closer on the left side than 
on the right. The right common iliac, except at its lower end, where it is in contact with 
the psoas, is separated from the structures named by the terminations of the right and 
left common iliac veins and the commencement of the inferior vena cava. The left 
common iliac, which is not so separated, lies on the inner border of the psoas. Somewhat 
deeply placed in the areolar tissue between the psoas and the lumbar vertebra, the 
obturator nerve, the lumbo-sacral cord, and the ilio-lumbar artery form posterior relations 
to the artery on both sides, 
Lateral.—On both sides of each artery are coils of small intestine. ‘The commence- 
ment of the inferior vena cava lies to the outer side of the upper part of the right artery, 
and on the inner side of this vessel are the right common iliac vein below and the left 
common iliac vein above. The last-named vein lies on the inner side of the left artery. 
THE PAIRED VISCERAL BRANCHES OF THE ABDOMINAL AORTA. 
1. Suprarenal or Capsular Arteries (aa. suprarenales, Fig. 566).—There are 
three sets of suprarenal arteries—the superior, middle, and inferior. Of these the 
middle only arise from the aorta direct; the superior spring from the inferior 
phrenic, and the inferior from the renal arteries. 
The middle suprarenal arteries are two small branches which arise, behind the 
pancreas, from the sides of the aorta, close to the origin of the superior mesenteric 
artery. They run, one on each side, outwards and upwards upon the crura of the 
diaphragm, and just above the renal arteries, to the suprarenal bodies to which they 
are distributed, and they anastomose with the superior and inferior suprarenal 
arteries. 
2. Renal Arteries (aa. renales, Fig. 566).—The renal arteries arise, one on 
each side, from the aorta, about half-an-inch below the origin of the superior 
mesenteric artery and opposite the first lumbar vertebra. 
Both arteries are of large size, and the right, which is a little longer than the 
left, is frequently slightly lower in position. Each artery runs almost transversely 
outwards to the hilus of the corresponding kidney. It passes in front of the crus 
of the diaphragm and of the upper part of the psoas muscle. The left artery hes 
behind the pancreas; the right vessel passes behind the inferior vena cava, the 
head of the pancreas, and the second part of the duodenum. The renal vein 
usually lies below and in front of the artery, but near the kidney the vein not un- 
frequently occupies a posterior position. 
On reaching the hilus of the kidney each artery divides into three branches, 
two of which pass in front of the pelvis of the ureter, and between it and the renal 
vein, and the third behind the pelvis. In the renal sinus these primary branches 
break up into numerous secondary branches which enter the kidney substance 
between the pyramids. 
Branches.—The following branches are given off by each renal artery, in addition to the 
terminal branches :— 
