498 THE ILIAC VEIXS. 



by which they are both invested. In the lower part of its course, the 

 vein receives all the branches which accompany the oflFsets of the chief 

 artery. In the upper part, the deep femoral vein ojiens into it, having 

 first received all the branches from muscles supplied by the deep femoral 

 artery. Near its termination the femoral vein is joined by the in- 

 ternal saphenous vein. 



Varieties. — The femoral vein occasionally pui'sues a course different from 

 that of the artery along the thigh. Extending iipwards from the popliteal space, 

 the vein in such cases perforates the adductor magnus above the ordinary posi- 

 tion, and. joining with the deep femoral vein, first approaches the femoral 

 ai-tery at tlie gToin. The same vein is sometimes double in a small part, or more 

 rarely in almost its whole length. 



EXTERNAL ILIAC VEIN. 



The external iliac vein is the continuation of the femoral vein from 

 Poupart's ligament to the junction of the internal iliac vein, in the 

 neighbourhood of the sacro-iHac articulation. It is at first iuternal to 

 the artery, and on the left side it continues in that position, but on the 

 right side it gradually inclines somewhat behind the artery. It does 

 not possess valves. 



Tributaries. — Xear its commencement at Poupart's ligament, the external 

 iliac vein receives the circumjlcx lUac and tlie cpifiastric veuis. 



INTERNAL ILIAC VEIN. 



The internal iliac vein is formed by the union of branches which 

 accompany the corresponding branches of the internal iliac artery. The 

 umbilical vein of the foetus, however, which in the cord accompanies the 

 corresponding arteries, diverges from these arteries within the body, 

 and passes upwards to the liver. The internal iliac vein lies behind 

 tlie corresponding artery in front of the sacro-iliac articulation, and, 

 after a short course upwards to the margin of the pelvis, joins with 

 the external iliac vein to form the common iliac. No valves are 

 found in the trunk of the internal iliac vein, but they exist in its 

 branches. 



Tributaries. — The tributaries of the internal iliac vein correspond 

 in general to the various branches of the internal iliac artery, with the 

 exception that the internal pudic vein docs not receive the main supply 

 of blood from the dorsal vein of the penis. The visceral veins are 

 remarkable for their size and frequent anastomoses, and have been 

 described as forming a series of plexuses, severally named the vesical, 

 jirostatir, JurmorrlioiilaJ, uterine, and varjinal. 



The vesical plexus consists of vessels which ramify over the whole 

 of the bladder external to its muscular coat, being particularly large and 

 numerous towards the base of the organ, where they are closely con- 

 nected with the prostatic and ha3morrhoidal plexuses in the male, and 

 with the vaginal plexus in the female. 



The prostatic plexus receives two large vessels, one at each side, 

 the divisions of tlie dorsal vein of the penis. These, coursing down- 

 wards and backwards on the sides of the prostate gland, expand 

 into a close network at the base of the gland, which is quite encircled 

 by it. 



The hsemorrhoidal plexus consists of enlarged and copiously anas- 

 tomosing veins in the walls of the lower part of the rectum, imme- 



