292 THE VASCULAR SYSTEMS 



The Inferior Vena Cava 



This large trunk arises at the fifth lumbar by the union of 

 the two common iliacs. It ascends to the right of the aorta, 

 grooves the posterior border of the liver, pierces the diaphragm, 

 is enclosed by the serous layer of the pericardium, and empties 

 into the right auricle. The Eustachian valve guards its orifice. 

 It receives the following tributaries: 



(a) The lumbar, corresponding to the arteries. 



(6) The spermatic forms within the spermatic cord a plexus, 

 the spermatic or pampiniform, which runs with the spermatic 

 artery through the inguinal canal, ending in several vessels 

 uniting into a single trunk. This vein, the spermatic, ascends 

 on the psoas behind the peritoneum, and joins the vena cava 

 on the right, the renal vein on the left side. 



In the female its analogue, the ovarian vein, forms the pam- 

 piniform plexus in the broad ligament and runs with the artery. 



(c) The renal veins run from the hilus of the kidney, in front 

 of the arteries, to join the vena cava at a right angle. The 

 left is longer and crosses the aorta. This vein receives some 

 small suprarenal branches and also the spermatic and supra- 

 renal veins. 



(d) The suprarenal run from the suprarenal bodies to the 

 vena cava on the right, the renal on the left side. 



(e) The inferior phrenic. 



(/) The hepatic veins, two or three, join the vena cava at 

 the groove in the liver through which the latter passes. 



The common iliac veins are formed by the junction of the 

 external and internal iliacs; they run from the base of the 

 sacrum to the upper part of the fifth lumbar vertebra, and 

 unite to form the inferior vena cava. The right is the shorter, 

 and is at first behind, later to the right, of its artery, while 

 the left is internal to its own artery, then behind the right 

 iliac artery. The common iliacs receive the following tribu- 

 taries : 



The iliolumbar. 



The two middle sacral, one on each side of the artery, anasto- 

 mose with the lateral sacral and hemorrhoidal veins, and unite 

 into a single vessel which joins the left common iliac vein. 



