THE INTERNAL ILIAC ARTERY. 813 



along the base of the broad ligament towards the neck of the uterus. Just before 

 reaching the uterus, usually about 2 cm. ( ^ in. ) from it, the artery crosses in front 

 of the ureter and then bends upward between the two layers of the broad ligament 

 along the side of the uterus. Arrived at the junction of the Fallopian tube with the 

 uterus, it bends outward along the lower border of the tube, and then, passing 

 beneath the hilum of the ovary, terminates by inosculating with the ovarian artery. 

 In its course between the layers of the broad ligament the artery is accompanied 

 by the large uterine veins, which almost conceal it, and both artery and veins are 

 enclosed in a rather dense sheath of areolar tissue. During pregnancy the artery 

 becomes much enlarged, and its course, as well as that of its branches, becomes 

 exceedingly sinuous and even spiral. 



Branches. — {a) As the uterine artery crosses the renal duct, a ureteral branch is supplied 

 to the ureter. On reaching the sides of the uterus, it gives off — 



{d) One or several cervical branches. These pass to the cervix and divide into numerous 

 branches which supply that portion of the uterus and the upper part of the vagina. They are 

 relatively long and tortuous, and anastomose below with the branches of the vaginal arteries. 

 Throughout the rest of its course along the sides of the uterus it gives oft' numerous — 



{c) Uterine branches, which, although tortuous, yet differ from the cervical branches in 

 being rather short. They pass to both the anterior and posterior surfaces of the uterus and 

 supply its body and fundus, and it is to be remarked that both these branches and the cervical 

 ones diminish rapidly in calibre as they branch upon the surface of the uterus, so that at the 

 middle line of the organ only exceedingly minute twigs are to be found. 



From the portion of the artery that runs outward along the lower border of the Fallopian 

 lube — 



{d) Tubal branches (rami tubarii) are given off. One of these, much stronger than the 

 others, arises just before the uterine inosculates with the ovarian artery, and passes outward 

 along the tube to its fimbriated extremity, sending branches to it through its entire course. 



{e) Ovarian branches (rami ovarii) to the ovary are finally given off from the uterine 

 artery in the vicinity of its anastomosis with the ovarian. 



8. The Middle Hemorrhoidal Artery. — The middle hemorrhoidal artery 

 (a. haemorrhoidalis media) (Fig. 726) is somewhat variable both in its origin and in 

 its size. It arises either from the anterior division of the internal iliac, below the 

 hypogastric artery, or, as frequently happens, from the inferior vesical or occasionally 

 from the internal pudic. It passes along the lateral surface of the middle portion of 

 the rectum, giving off branches which, in addition to aiding in supplying the vagina 

 and communicating with t* vaginal arteries, anastomose above with the superior 

 hemorrhoidal from the inferior mesenteric and below with the inferior hemorrhoidal 

 from the internal pudic. 



9. The Obturator Artery. — The obturator artery (a. obturatoria) (Fig. 724) 

 arises from the anterior division of the internal iliac, below the hypogastric axis. It 

 passes forward along the lateral wall of the pelvis, resting upon the pelvic fascia 

 which covers the upper portion of the internal obturator muscle, and having the 

 obturator nerve immediately above it and the vein below. Just before reaching the 

 anterior wall of the pelvis it is crossed by the vas deferens in the male, as it passes 

 downward from the internal abdominal ring, and then it pierces the pelvic fascia and 

 makes its exit from the pelvic cavity through the obturator canal, on emerging from 

 which it divides into two terminal branches, an internal and an external. 



Branches. — Within the pelvis the obturator artery gives off several small branches, of 

 which the more important are — 



(a) An iliac branch, which is given oft" near the origin of the obturator and passes up to 

 the iliac fossa, supplying the ilio-psoas muscle, giving nutrient branches to the ilium and anasto- 

 mosing with the iliac branch of the ilio-lumbar artery. 



(6) Muscular branches, which are distributed to the obturator internus and the levator ani. 



{c) Vesical branches, which pass to the bladder beneath the false lateral ligament and 

 anastomose with branches from the superior vesical ; and 



{d) A pubic branch (ramus pubiciis) which arises just before the artery enters the obtu- 

 rator canal and ascends upon the posterior surface of the os pubis to anastomose above with the 

 pubic branch of the deep epigastric artery. 



Outside the pelvis the obturator artery divides into an external and an internal branch. 



