THE POSTERIOR VENA CAVA. 709 



1. Internal Iliac Vein. 



This vessel is formed by the satellite veins of the branches furnished by 

 the homonymous artery ; these are the iliaco-femoraU obturator, iliaco-mKsndar, 

 gluteal, lateral sacral, and infernal piulir, the distribution of which does not differ 

 from that of the corresponding arterial divisions. 



The trunk resulting from the union of these different l)ranches is usually 

 very short ; it may even be altogether absent, and we then see the veins which 

 should form it, open into the common iliac vein by forming two or three separate 

 groups, situated very close to each other. 



2. External Iliac Vein. 



This vein constitutes the principal root of the common iliac, which is but 

 a continuation of it — the internal iliac being only, properly speaking, a collateral 

 affluent of the single canal represented by the external and common iliac veins. 



Situated behind the iliac artery, this external iliac vein commences at the 

 anterior border of the pubis, where it is directly continued, without any line of 

 demarcation, by the femoral vein. 



The only important vessel it receives on its course is the iliac circumflex vein, 

 which, however, opens more frequently into the common than the external iliac. 



3. Femoral Vein. 



Continuous by its superior extremity with the external iliac vein, and 

 inferiorly with the popliteal, the femoral vein is remarkable for its large volume ; 

 it closely follows the artery of the same name throughout its extent (Fig. 

 389, 5). 



The collateral affluents it receives in its course are distinguished by their 

 number and considerable volume. They are : — 



1. The satellite veins of the muscular arteries. 



2. The internal saphena vein, which will be again referred to in describing 

 the superficial veins of the leg. 



3. The prepuMc vein, formed by the posterior abdominal and the branches of 

 the internal pudic. The latter are very numerous and large, and anastomose 

 with each other, forming between the thighs, in the texture of the scrotum and 

 sheath, and above the penis, a very rich network which communicates behind 

 with the cavernous veins. This network only sends a small trunk into the 

 inguinal canal, along the external pudic artery ; in its middle part it opens into 

 an enormous branch which passes thi'ough the ring in the sartorius muscle, and 

 is lodged in the inferior groove of the pubis to join the femoral vein. 



One of these external pudic veins represents the subcutaneous abdominal 

 vein, and communicates with the subcutaneous thoracic vein. 



All these branches in the female show an analogous disposition. 



4. Popliteal Vein. 



Satellite of the popliteal artery, this vein is formed by the union of the 

 anterior and posterior tibial veins. 



Among the branches it receives on its course, the femoro-poplifeal vein may be 

 particularly noted : this accompanies the artery of the same name, and joins the 

 external saphena before opening into the popliteal vein. 



