844 A MANUAL OF ANATOMY 



of the iliac fossa, it divides into two branches, iliac and lumbar, 

 The iliac branch, passing transversely, ramifies in the iliacus and 

 ilium, and anastomoses with the iliac branch of the obturator and 

 branches of the deep circumflex iliac from the external iliac. 

 The lumbar branch ascends beneath the psoas magnus on to the 

 quadratus lumborum, where it anastomoses with the terminal 

 part of the deep circumflex iliac, and the last lumbar of the ab- 

 dominal aorta. In its course it furnishes a spinal branch, which 

 enters the spinal canal through the intervertebral foramen between 

 the fifth lumbar and first sacral vertebrae, to be distributed in a 

 manner similar to the other spinal arteries. 



The lateral sacral arteries (P) are usually two in number, superior 

 and inferior. They course downwards and inwards to the front 

 of the lateral mass of the sacrum, passing in front of the pyriformis 

 and sacral nerves. Upon the sacrum both arteries lie external to 

 the anterior sacral foramina, the superior being confined to the 

 region of the first two foramina, whilst the inferior descends as 

 low as the coccyx, where it anastomoses with the middle sacral 

 artery. They are distributed to the pyriformis and sacral nerves, 

 and furnish spinal branches, which enter the anterior sacral 

 foramina, and so reach the sacral canal, where they supply its 

 contents. Each spinal branch, before entering the sacral canal, 

 gives of? a posterior branch, which emerges through the posterior 

 sacral foramen, and anastomoses with branches of the gluteal, 

 sciatic, and internal pudic. The lateral sacral arteries anastomose 

 with each other and with the middle sacral. 



The gluteal artery (P) is a large vessel, which is the continuation 

 of the posterior division. It is destined for the supply of the 

 gluteal region, and lies within the pelvis for a very short dis- 

 tance. Its direction is backwards through the parietal pelvic 

 fascia, and between the lumbo-sacral cord and the anterior 

 primary division of the first sacral nerve, its escape from the 

 pelvis being through the upper compartment of the great sacro- 

 sciatic foramen. The branches of the artery within the pelvis are 

 unimportant. 



For the extrapelvic course and distribution of the vessel, see 

 p. 430. 



The branches of the internal iliac, with one exception, have to 

 pierce the pelvic fascia. The exception is the obturator artery, 

 which, as stated, passes over the upper border of the parietal pelvic 

 fascia at the obturator canal. 



Internal Iliac Vein. — This vessel results from the union of branches 

 which correspond, for the most part, with branches of the internal 

 iliac artery. The ilio-lumbar vein, however, is an exception, inas- 

 much as it is a tributary of the common iliac vein. Moreover, 

 during foetal life the umbilical vein, which corresponds to the 

 hypogastric (subsequently umbilical) artery, passes to the liver 

 after entering the abdomen of the foetus. The internal iliac vein 

 extends from the upper part of the great sciatic notch to the sacro- 



