YESICAL ARTERIES. 421 



contact with one another and with the umbilical vein, and, coiling spirally 

 round that vein in the umbilical cord, they proceed to the placenta. To 

 that part of the artery which is placed within the abdomen, the term hypo- 

 gastric is applied ; the remaining portion, passing onwards through the 

 umbilicus to the placenta, being the proper umbilical artery. After the 

 cessation of the placental circulation at birth, the two hypogastric arteries 

 become impervious from the side of the bladder upwards to the umbilicus, 

 and are converted into fibrous cords. These two cords, which extend 

 from the sides of the bladder to behind the umbilicus, being shorter than 

 the part of the peritoneum on which they rest, cause a fold of the serous 

 membrane to project inwards ; and thus are formed two fossae (fossae of the 

 peritoneum) on each side of the abdomen, in one or other of which the pro- 

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

 intervening between the origin of the vessel and the side of the bladder 

 remains pervious, although proportionally much reduced in size, and forms 

 the trunk of the superior vesical artery. 



BRANCHES OF THE INTERNAL ILIAC ARTERY/. 



I. VESICAL ARTERIES. 



The urinary bladder receives several arteries, amongst which, however, 

 may be specially recognised two principal branches, a superior and an inferior 

 vesical artery. 



The superior vesical artery is, at its commencement, that part of the 

 hypogastric artery in the fcetus which remains pervious after the changes 

 that take place subsequently to birth. It extends from the anterior di- 

 vision of the internal iliac to the side of the bladder. 



BRANCHES. (a) It distributes numerous branches to the upper part and sides of 

 the bladder. 



(6) The artery of the vas deferens, or the deferent artery, 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 

 anastomoses with the 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 distributed to the 

 base of the bladder, to the side of the prostate, and to the vesiculse semi- 

 nales. 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 likeAvise. 



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

 deficient pudic arteries replace one or more of their branches, as will be more fully 

 noticed under those arteries. 



Besides the superior and inferior vesical arteries, other smaller branches will be 

 found to reach the bladder, and usually one slender vessel which is distributed parti- 

 cularly to the under surface of the vesiculae seminales. 



Middle hcemorrhoidal artery. This branch is usually supplied to the 

 rectum by the inferior vesical artery, but sometimes proceeds from other 



