INTERIOR OF THE PELVIS. 209 



and enters the pelvis again by the lesser sacro ischiatio foramen to 

 reach the ramus of the ischium, beneath the edge of which it passes, 

 giving off the periueal branches described at page 202, and terminating 

 in the dorsalis penis artery. 



The uterine artery, arising from the anterior division of the inter- 

 nal iliac, passes between the layers of the broad ligament and reach- 

 ing the neck returns to the fund us of the uterus, giving off branches 

 to the surface and substance of that vise us ; it is usually more or 

 less tortuous, and anastomoses freely with the ovarian artery, a branch 

 from the abdominal aorta analogous to the spermatic artery of the 

 male (p. 180). During pregnancy the uterine arteries increase greatly 

 in size, and become still more tortuous. The ovarian artery passes 

 between the layers of the broad ligament, and, after many tortuous 

 convolutions, penetrates the ovary. 



The raginal artery seldom arises directly from the inteiual iliac; 

 given off frequently from the uterine, or from the middle hemorrhoidal, 

 it passes down in the posterior wall of the vagina to anastomose, near 

 its termination, with the corresponding artery of the other side. Both 

 the uterine and vaginal arteries give small branches to the bladder 

 and rectum. 



The posterior trunk of the internal iliac artery gives off 

 the following branches : 



Ilio-lumbar, Lateral Sacral, Gluteal. 



The ilio-lumbar artery passes upward and then outward, beneath 

 the external iliac, to the crest of the ilium ; it there divides into two 

 branches, one of which supplies the iliacus internus by ramifications 

 between the muscle and the bone, forming numerous anastomoses 

 with the circumfl-exa ilii from the external iliac ; the other branch 

 passes upward to supply the psoas and quadratus lumborum. This 

 artery is analogous to the lumbar arteries ; it varies considerably in 

 its precise point of origin. 



The lateral sacral artery passes down upon the side of the sacrum 

 to the coccyx, inosculating with the sacra media. It sends branches 

 through the anterior sacral foramina to the terminal portion of the 

 spinal cord, and these, finally emerging at the posterior sacral fora- 

 mina, supply the posterior surface of the sacrum. 



The gluteal artery is a short, thick trunk, the apparent continuation 

 of the posterior division of the internal iliac; it p-isses out of the 

 pelvis at the greater sacro-ischiatic foramen, above the border of the 

 pyriformis muscle, with the superior gluteal nerve, and is distributed 

 to the gluteal muscles, as will be seen in the description of that 

 region. 



The superior hemorrhoiJal artery, a branch of the infe- 

 rior mesenteric, will be found distributed to the upper part 

 of the rectum; it lies between the two layers of peritoneum 

 constituting the meso-rectum, and anastomoses with the 

 middle and external hemorrhoidal arteries. 



All of the arteries just described are accompanied by 

 18* 



