Chap. XI] 



THE VASCULAR SYSTEM 



207 



k 



popliteal veins and extend from the opening in the adductor 

 magnus to the level of the inguinal ligament. 



The external iliacs. — These vessels are 

 a continuation of the femoral veins, and 

 extend from the level of the inguinal (Pou- 

 part's) ligament, on either side. to the joint 

 between the sacrum and the ilium. They 

 receive the blood from the deep and super- 

 ficial veins of the lower limbs. 



The internal iliacs. — They are formed 

 by the union of veins corresponding to the 

 branches of the internal iliac arteries. They 

 accompany the internal iliac arteries and 

 unite with the external iliac veins to form 

 the common iliacs. 



The common iliacs. — The common iliacs 

 extend from the base of the sacrum to the 

 fourth lumbar vertebra, and then the two 

 common iliacs unite to form the inferior 

 vena cava. ^ 



The inferior vena cava. — The inferior, or 

 ascending, vena cava, returns the blood from 

 the lower limbs, pelvis, and abdomen. It 

 begins at the junction of the two common 

 iliacs, and thence ascends along the right 

 side of the aorta, perforates the diaphragm, 

 and terminates by entering the right auricle 

 of the heart. The inferior vena cava re- 

 ceives many tributaries, the chief of which 

 are the lumbar, ovarian, renal, and hepatic 

 veins. 



Supplementary channel. — A supplemen- 

 tary channel between the inferior and su- 

 perior vena cava is formed by the azygos 

 veins. They are three in number and lie on 

 the sides of the front of the vertebral bodies. 



The right or great azygos vein is an upward continuation of the 

 lumbar vein which communicates with the common iliac vein, 

 and often with the inferior vena cava and renal vein. It ascends 



Fig.' 134. — Super- 

 ficial Veins of the 

 Dorsum of the Leg. 

 (Gerrish.) 



