BRANCHES OF INTERNAL ILIAC. 515 



muscle and the obturator nerve, but in front of the lumbo-sacral nerve, 

 and divides into an ascending and a transverse branch in the iliac fossa : 



The ascending or lumbar branch, which is beneath the psoas, supplies 

 that muscle and the quadratus lumborum, and anastomoses with the last 

 lumbar artery : it sends a small spinal branch through the foramen be- 

 tween the sacrum and the last lumbar vertebra. 



The transverse or iliac offset divides into branches that ramify in the 

 iliacus muscle, some running over and some beneath it. At the iliac crest 

 these branches anastomose with the lumbar and circumflex iliac arteries ; 

 and some deep twigs communicate with the obturator artery, and enter 

 the innominate bone. 



The lateral sacral arteries (fig- 176, z) are two in number, superior 

 and inferior, but the upper is the larger ; they correspond in situation with 

 the lumbar arteries, and form a chain of anastomoses by the side of the 

 apertures in the sacrum. These arteries supply the pyriformis and coccy- 

 geus muscles, and anastomose with each other, as well as with the middle 

 sacral. A small spinal branch enters each aperture in the sacrum. 



The gluteal artery (fig. 176, m) is a short thick trunk, which appears 

 to be the continuation of the posterior division of the internal iliac. Its 

 destination is to the gluteal muscles on the dorsum of the hip bone ; and 

 it is transmitted from the pelvis above the pyriformis muscle, with its 

 accompanying vein, and the superior gluteal nerve. In the pelvis the 

 artery gives small branches to the contiguous muscles, viz., iliacus, pyri- 

 formis, and obturator, and a nutritious artery to the hip bone. 



B. The branches of the anterior portion of the internal iliac artery are 

 the following : 



The vesical arteries, superior and inferior, are distributed to the upper 

 and lower parts of the bladder. 



The upper, three or four in number, arise at intervals from the partly 

 obliterated hypogastric trunk ; the lowest of these is sometimes called 

 middle vesical branch. Offsets are furnished from those branches to all 

 the body and upper part of the bladder. 



The lower artery arises from the internal iliac in common with a 

 branch to the rectum, or with one to the vagina in the female. It is dis- 

 tributed to the base of the bladder, the vesiculse seminales, and the pros- 

 tate. A small offset from this artery or from the upper vesical is furnished 

 to the vas deferens. 



The branch to the rectum (middle hremorrhoidal) is commonly supplied 

 by the inferior vesical. It is spent on the anterior and lower part of the 

 rectum, and on the vagina in the female, and anastomoses with the haemor- 

 rhoidal arteries. 



The obturator artery (fig. 176J &). The branch is directed forwards 

 below the brim of the pelvis to the aperture in the upper part of the thy- 

 roid foramen ; passing through that opening it ends in two branches, 

 which ramify on the membrane closing the thyroid foramen, and lie be- 

 neath the muscle in that situation. In the pelvis the artery has its com- 

 panion nerve above, and vein below it ; and it gives origin to the following 

 small branches. 



Jliac branch : this small offset enters the iliac fossa to supply the bone 

 and the iliacus muscle; it anastomoses with the ilio-lumbar artery. 



The pubic branch (fig. 141,_/') ascends on the posterior aspect of the 

 pubes, and communicates with the corresponding branch of the opposite 

 side, and with an offset from the epigastric artery. 



