440 BEANCHES OF INTEEXAL ILIAC AETEEY. 



an inch in length. An instance has been observed in which this vessel was 

 absent, and its branches were derived from a bend of the external iliac artery 

 down into the pelvis (Preparation in Univ. Coll. Mus.. London). The lengths of 

 the common iliac and internal iliac arteries bear an inverse proportion to each 

 other — the internal iliac being long when the common iliac is sliort, and ria^ 

 vend. Moreover, when the common iliac is short, the internal iliac (arising 

 higher than usual) is placed for some distance above the brim of the pelvis, and 

 descends by the side of the external iliac to reach that cavity. 



The jjlacc of divifiio7i of the internal iliac into its branches varies between the 

 upper margin of the sacrum and the upper Imrder of the sacro-sciatic foramen. 



JBranchc.s. — Sometimes all the branches of the internal iliac ai-tery arise without 

 the previous separation of that vessel into two portions. 



In more than a fourth of E. Quain's cases a biTinch. corresponding usually to 

 the ilio-lumbar artery, arose before the subdivision of the main trunk. 



Hypog-astric Ai-tery. — /;/ the fwt lift, the internal iliac artery, retaining almost 

 the full size of the common iliac, curves forwards from that artery to the side of 

 the urinary bladder, and ascends on the anterior wall of the abdomen to the 

 umbilicus. There the vessels of opposite sides come into contact with one 

 another, and with the umbilical vein, and coiling spirally round that vein in the 

 umbilical cord, thej' proceed to the placenta. To that part of the artery which 

 is placed within the abdomen, the term hjijKit/dKtric is applied : the remaining 

 portion, passing onwards through the umbilicus to the placenta, ]:)eing the proj^er 

 iimbUical artery. After the cessation of the placental circulation at birth, the 

 two hypogastric arteries become impervious from the side of the bladder ujjAvards 

 to the umbilicus, and are converted into fibrous cords. These two cords, being 

 shorter than the pai-t of the peritoneum on which they rest, cause a fold of the 

 serous membrane to project inwards ; and thus are formed two fossaj (external and 

 internal fossa; of the peritoneum) on each side of the abdomen, in one or other of 

 which the projection of a direct inguinal hernia takes place. The part of the artery 

 intervening between its origin and the side of the bladder remains pervious, 

 although proportionally much reduced in size, and fonns the tn.uik of the 

 superior vesical artery. 



BRANCHES OF INTERNAL ILIAC ARTERY. 



The superior vesical artery is, at its commencement, tliat part of 

 the hypogastric artery in the foetus wliich remains pervious after the 

 changes that take place subsequently to birth. It e.xtends from the 

 anterior division of the internal iliac to the side of the bladder. 



Branches.— ((?) It distributes numerous branches to the upper part and sides 

 of the bladder. 



(b) The artcri/ of the vast deferens, arising from one of the lowest of these, is a 

 slender artery which reaches the vas deferens, and accompanies that duct in its 

 course through the spermatic cord to the back of the testicle, where it anasto- 

 moses with tlie spermatic artery. 



(c) Other small branches ramify on the lower end of the ureter. 



The inferior vesical artery (vesico-prostatic), derived usually from 

 the anterior division of the internal iliac, is directed downwards'^to the 

 lower part of the bladder, where it ends in branches which are distri- 

 buted to the base of the bladder, to the side of the prostate, and to the 

 vesiculse seminales. One offset, to be presently described, descends 

 upon the rectum. 



The branches upon the prostate communicate more or less freely upon that 

 body with the corresponding vessels of the opposite side, and, according to Haller, 

 with the perineal arteries. 



Small twigs of this vessel also run towards the subpubic arch, and in instances 



