264 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



forward on the inner surface of the skin of the abdominal wall and anastomoses 

 with the external mammary, a branch of the long thoracic. These vessels are 

 particularly prominent in females, but the greater part of their course is 

 destroyed in removing the skin. The external iliac, now named the femoral, 

 proceeds along the center of the medial surface of the thigh, giving branches into 

 the leg muscles. For these branches consult R and J, and B. 



Follow the internal iliacs, being careful not to injure the end of the post- 

 caval vein lying in contact with them nor any parts of the urogenital system 

 (in males do not injure the male ducts curving around the base of the urinary 

 bladder). The internal iliacs lie against the dorsal wall. At their origin from 

 the common iliac (rabbit) or posterior to their origin from the dorsal aorta (cat) 

 each gives rise to an umbilical artery which passes to the bladder or in female 

 rabbits to the uterus first with a branch to the bladder. The internal iliacs then 

 pass to the dorsal side of the postcaval vein. To follow them dissect as deeply 

 as possible between the rectum and the base of the thigh. The internal iliacs 

 give some branches to the pelvis and then each gives off a middle haemorrhoidal 

 artery to the rectum. This accompanies the rectum to the anus but cannot be 

 followed at this time. In female cats the uterine artery arises from the middle 

 haemorrhoidal and passes anteriorly again to the uterus. The internal iliacs 

 cannot be followed farther conveniently. They give branches to the tail and 

 thigh. 



Draw the branches of the iliacs adding them to the drawing of the dorsal 

 aorta already made. 



7. The posterior portion of the postcaval vein. The postcaval may now be 

 followed caudad from the point where it was previously left by removing the 

 arteries which cover it. Its tributaries should be traced as far as practicable to 

 the posterior end of the peritoneal cavity, dissecting deeply dorsally as before. 



Rabbit: The postcaval receives, at the same level as the forking of the dorsal 

 aorta, the two large external iliac veins. It then continues in the mid-dorsal 

 line for a short distance caudad to this point, this portion often receiving the 

 name of common internal iliac vein, and is then seen to be formed by the union 

 of the two internal iliac or hypogastric veins. Trace the external iliac; its 

 branches are similar to and accompany those of the artery of the same name. 

 It soon receives the vesical vein from the bladder : this vein in females also collects 

 from the uterus. At the place where it passes through the abdominal wall, the 

 external iliac receives the inferior epigastric vein. The main part of this runs 

 forward along the internal surface of the rectus abdominis muscle and anasto- 

 moses anteriorly with the superior epigastric. The inferior epigastric near its 

 place of entrance into the external iliac also receives tributaries from the fat 

 between the bases of the thighs and the external genital region, and sends a 

 superficial epigastric vein along the inner surface of the skin of the lateral abdomi- 

 nal wall. This last-named vessel is particularly conspicuous in females, but is 



