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. _b._ =A. glutea superior= (Fig. 126, _p_).--This passes dorsolaterad from the hypogastric and reaches the pelvic wall against the medial surface of the ilium. Here it divides into two branches. One passes between the iliopsoas muscle and the ventral border of the ilium to the medial surface of the gluteus maximus; it gives branches to the gluteus muscles, the pyriformis, and the rectus femoris. The other branch passes dorsad of the ilium, sending a branch to the medial surface of the gluteus medius, and a small branch which joins the lateral sacral artery and enters thus the sacral canal.