THE ARTERIES. 3°7 
between the centra of the vertebra 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. 
g. A. iliaca externa (Fig. 126, ).—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 (7). The branches of the external iliac artery 
are described below (page 300). , 
10. A. hypogastrica (or iliaca interna) (Fig. 126, /).—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 struc- 
tures 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 () is given off. The hypogastric artery, 
then extends two or three centimeters and gives off A. 
glutea superior (f), which passes at once to the pelvic 
wall. A little farther caudad the hypogastric divides into the 
middle hemorrhoidal (7), to the rectum, and the glutea in- 
ferior (7), which passes out of the pelvis. 
Branches of the hypogastric artery: 
a. A. umbilicalis (Fig. 126, “).—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. 
