OBTURATOR. 511 



a slender vessel is derived, which accompanies the vas deferens in its course to 

 the testis, where it anastomoses with the spermatic artery. This is the artery 

 of the vas deferens. Other branches supply the ureter. 



The middle vesicle, usually a branch of the superior, is distributed to the base 

 of the bladder, and under surface of the vesiculae seminales. 



The inferior vesicle arises from the anterior division of the internal iliac, in 

 common with the middle hasmorrhoidal, and is distributed to the base of the 

 bladder, the prostate gland, and vesiculae seminales. The branches distributed 

 to the prostate communicate with the corresponding vessel of the opposite side. 



The middle hsemorrhoidal artery usually arises together with the preceding 

 vessel. It supplies the rectum, anastomosing with the other hasmorrhoidal 

 arteries. 



The uterine artery passes downwards from the anterior trunk of the internal 

 iliac to the neck of the uterus. Ascending, in a tortuous course, on the side of 

 this viscus, between the layers of the broad ligament, it distributes branches to 

 its substance, anastomosing, near its termination, with a branch from the ova- 

 rian artery. Branches from this vessel are also distributed to the bladder and 

 ureter. 



The vaginal artery is analogous to the inferior vesical in the male ; it descends 

 upon the vagina, supplying its mucous membrane, and sending branches to the 

 neck of the bladder and contiguous part of the rectum. 



The obturator artery usually arises from the anterior trunk of the internal iliac, 

 frequently from the posterior. It passes forwards below the brim of the pelvis, 

 to the canal in the upper border of the obturator foramen, and escaping from 

 the pelvic cavity through this aperture, divides into an internal and an external 

 branch. In the pelvic cavity this vessel lies upon the pelvic fascia, beneath the 

 peritoneum, and a little below the obturator nerve ; and, whilst passing through 

 the obturator foramen, is contained in an oblique canal, formed by the horizon- 

 tal branch of the pubes, above ; and the arched border of the obturator mem- 

 brane, below. 



Branches. Within the pelvis, the obturator artery gives off an iliac branch to 

 the iliac fossa, which supplies the bone and the Iliacus muscle, and anastomoses 

 with the ilio-lumbar artery ; a vesical branch, which runs backwards to supply 

 the bladder; and a pubic branch, which is given off from the vessel just before 

 it leaves the pelvic cavity. This branch ascends upon the back of the pubes, 

 communicating with offsets from the epigastric artery, and with the correspond- 

 ing vessel of the opposite side. This branch is placed on the inner side of the 

 femoral ring. External to the pelvis, the obturator artery divides into an external 

 and an internal branch, which are deeply situated beneath the Obturator Exter- 

 nus muscle ; skirting the circumference of the obturator foramen, they anasto- 

 mose at the lower part of this aperture with each other, and with branches of 

 the internal circumflex artery. 



The internal branch curves inwards along the inner margin of the obturator 

 foramen, distributing branches to the Obturator muscles, Pectineus, Adductors, 

 and Gracilis, and anastomoses with the external branch, and with the internal 

 circumflex artery. 



The external branch curves round the outer margin of the foramen, to the 

 space between the Gemellus Inferior and Quadratus Femoris, where it anasto- 

 moses with the sciatic artery. It supplies the Obturator muscles, anastomoses, 

 as it passes backwards, with the internal circumflex, and sends a branch to the 

 hip-joint through the cotyloid notch, which ramifies on the round ligament as 

 far as the head of the femur. 



Peculiarities. In two out of every three cases the obturator arises from the internal iliac ; 

 in one case in 3 from the epigastric ; and in about one in seventy-two cases by two roots from 

 both vessels. It arises in about the same proportion from the external iliac artery. The origin 

 of the obturator from the epigastric is not commonly found on both sides of the same body. 



When the obturator artery arises at the front of the pelvis from the epigastric, it descends 

 almost vertically to the upper part of the obturator foramen. The artery in this course usually 



