BRANCHES OF THE INTERNAL ILIAC ARTERY. 807 
The artery to the vas (a. deferentialis), which not unfrequently arises from the 
superior vesical, is a long slender vessel which runs downwards to the vas and 
vesicula seminales, and is then continued with the vas deferens to the testicle, 
where it anastomoses with the spermatic artery. It also anastomoses with the 
cremasteric branch of the deep epigastric artery. 
5. The middle hemorrhoidal artery (a. htemorrhoidalis media) is an irregular 
branch which arises either directly from the anterior division of the internal iliac or 
from the inferior vesical branch; more rarely it springs from the internal pudic 
artery. It runs inwards, and is distributed to the muscular coats of the rectum ; 
it also gives branches to the prostate, the seminal vesicle, and the vas deferens, and it 
anastomoses with its fellow of the opposite side, with the inferior vesical, and with 
the superior and inferior hemorrhoidal arteries. 
6. The vaginal artery (a. vaginalis) in the female usually corresponds to 
the inferior vesical in the male; in which ease it arises from the anterior division 
of the internal iliac, either independently or in common with the uterine artery. 
Occasionally both inferior vesical and uterine vessels are present, and not un- 
commonly the vaginal artery is represented by several branches. 
The vaginal arteries run downwards and inwards on the floor of the pelvis 
to the sides of the vagina; and divide into numerous branches which ramify 
on its anterior and posterior walls. The corresponding branches of opposite 
sides anastomose and form anterior and posterior longitudinal vessels, the so-called 
azygos arteries. They also anastomose above with the cervical branches of the 
uterine artery, and below with the perineal branches of the internal pudic. In 
addition to supplying the vagina, small branches are given to the bulb of the 
vestibule, to the base of the bladder, and to the rectum. 
7. The uterine artery (a. uterina) arises from the anterior division 
of the internal iliac, either separately or in common with the vaginal or middle 
hemorrhoidal arteries. It runs inwards and slightly forwards, upon the upper 
surface of the levator ani, to the lower border of the broad ligament, between the 
two layers of which it passes inwards, and arches above the ureter about three 
quarters of an inch from the uterus. It passes above the lateral fornix of the 
vagina to the side of the neck of the uterus, and is then directed upwards, until 
it almost reaches the fundus, just below which, however, it turns outwards beneath 
the isthmus of the Fallopian tube and anastomoses with the ovarian artery. 
It supplies the uterus, the upper part of the vagina, the inner part of the 
Fallopian tube, and gives branches to the round ligament of the uterus. It 
anastomoses with its fellow of the opposite side, and with the vaginal, the ovarian, 
and the deep epigastric arteries. 
PARIETAL BRANCHES OF THE ANTERIOR DIVISION OF THE INTERNAL ILIAC. 
1. The obturator artery (a. obturatoria, Figs. 569 and 572) runs forwards and 
downwards along the lateral wall of the true pelvis, just below its brim, to the 
obturator foramen, through the upper part of which it passes. It terminates im- 
mediately on entering the thigh by dividing into internal and external terminal 
branches which skirt round the margin of the obturator foramen beneath the 
obturator externus muscle. It is accompanied in the whole of its course by the 
obturator nerve and vein, the former being above it and the latter below. 
To its outer side is the pelvic fascia, which intervenes between it and the upper 
part of the obturator internus muscle, whilst on its inner side it is covered by 
peritoneum; between the peritoneum and the artery is the ureter. When the 
bladder is distended it also comes into close relation with the anterior part of the 
artery. In the female the ovarian vessels and the broad ligament are on the inner 
side of the obturator artery. 
Branches.—All the branches except the terminal are given off before the artery 
leaves the pelvis. They include :—(a) Muscular branches to the obturator intermus 
levator ani and ilio-psoas muscles. (+) A nutrient branch to the ilium, which passes 
beneath the ilio-psoas muscle, supplies the bone, and anastomoses with the iliolumbar 
artery. (c) A vesical branch, or branches, pass inwards to the bladder beneath the 
