208 ANATOMY OF THE ABDOMEN, ETC. 



vein and the lumbo-sacral nerve ; the ureter crosses it and 

 separates it from the peritoneum. The length of the 

 internal iliac is subject to great variation, and its branches 

 are often irregular as to their precise point of origin, some- 

 times arising without the separation of the vessel into two 

 trunks ; they may all be determined by the parts to which 

 they are distributed. 



The anterior trunk gives off the following branches : 



Superior Yesical, Obturator, 



Inferior Vesical, Ischiatic, 



Internal Pudic ; 



and in the female subject, these two in addition : 

 Uterine, Vaginal. 



The Tiypogastric artery, during foetal existence, passes from the in- 

 ternal iliac artery, over the bladder and along the anterior parietes of 

 the abdomen, beneath the peritoneum, to the umbilicus, and thence, 

 with its fellow and the umbilical vein, to the placenta, forming the 

 umbilical cord. At the close of intra-uterine life, it becomes oblit- 

 erated to within an inch and a half of its commencement, leaving an 

 impervious cord ; the portion remaining pervious gives origin to the 

 superior vesical arteries. 



The superior vesical arteries are three or four in number, arising at 

 intervals from the stump of the hypogastrie, and are distributed to 

 the upper part of the bladder ; the most inferior of the branches is 

 sometimes called the middle vesical artery. 



The inferior vesical artery arises from the internal iliac, in common 

 with a branch to the rectum ; it is distributed to the base of the 

 bladder, the vesiculse serainales and prostate. The branch to the 

 rectum is called the middle hemorrhoidal ; it supplies the lower part 

 of the rectum, and the vagina in the female, anastomosing with the 

 superior and external hetrtorrhoidal arteries ; it sometimes arises from 

 the internal pudic. 



The obturator artery, already referred to (p. 201), arises from the 

 anterior division of the internal iliac; it passes foiward, accom- 

 panied by the obturator nerve, which lies above it, to the upper part 

 of the obturator foramen, beneath the horizontal branch of the pubes, 

 where it passes out of the pelvis and divides into its terminal branches. 

 The obturator sends a small twig to the iliacus muscle, and another 

 to the posterior surface of the pubes. 



The ischiatic artery is the largest branch of the anterior division of 

 the internal iliac ; it passes downward, lying upon the sacral plexus 

 of nerves, and leaves the pelvis, jnst in front of the sciatic nerve, 

 through the greater sacro-ischiatic foramen, to be distributed to the 

 muscles of the gluteal region and the back of the thigh. Within the 

 pelvis it gives off small branches to the rectum and base of the 

 bladder. 



The internal pudic artery is another branch of large size. It passes 

 down in front of the ischiatic artery, and emerges from the pelvis at 

 the great sacro-ischiatic foramen, crosses the spine of the ischium 



