INFERIOR VENA CAVA. 347 



bar vertebra. It ascends along the front of the vertebral column, on the 

 right side of the abdominal aorta, and passing through the fissure in the 

 posterior border of the liver and the quadrilateral opening in the tendinous 

 centre of the diaphragm, terminates in the inferior and posterior part of 

 the right auricle. There are no valves in this vein. 



It is in relation from below upwards, in front with the mesentery,trans- 

 verse duodenum, portal vein, pancreas, and liver, which latter nearly and 

 sometimes completely surrounds it ; behind it rests on the vertebral column 

 and right crus of the diaphragm, from which it is separated by the right 

 renal and right lumbar arteries ; to the right it has the peritoneum and 

 sympathetic nerve ; and to the left the aorta. 



The Brandies which the inferior cava receives in its course, are the 



Lumbar, 



Right spefmatic, 



Renal, 



Supra-renal, 



Phrenic, 



Hepatic. 



The Lumbar veins, three or four in number on each side, collect the 

 venous blood from the muscles and integument of the loins, and from the 

 spinal veins : the left are longer than the right on account of the position 

 of the vena cava. 



The Right spermatic vein is formed by the two veins which return the 

 blood from the venous plexus situated in the spermatic cord. These veins 

 follow the course of the spermatic artery, and unite to form the single trunk 

 which opens into the inferior vena cava. The left spermatic vein terminates 

 m the left renal vein. 



The Ovarian veins represent the spermatic veins of the male, and collect 

 the venous blood from the ovaries, round ligaments, and Fallopian tubes, 

 and communicate with the uterine sinuses. They terminate as in the 

 male. 



The Renal or emulgent veins return the blood from the kidneys ; their 

 branches are situated in front of the divisions of the renal arteries, and the 

 left opens into the vena cava somewhat higher than the right. The left 

 is longer than the right in consequence of the position of the vena cava, 

 and crosses the aorta immediately below the origin of the superior mesen- 

 teric artery. It receives the left spermatic vein, which terminates in it at 

 right angles : hence the more frequent occurrence of varicocele on the left 

 than on the right side. 



The Supra-renal veins terminate partly in the renal veins, and partly in 

 the inferior vena cava. 



The Phrenic veins return the blood from the ramifications of the phrenic 

 arteries ; they open into the inferior cava. 



The Hepatic veins form two principal trunks and numerous smaller veins 

 which open into the inferior cava, while that vessel is situated in the pos- 

 terior border of the liver. The hepatic veins commence in the liver by 

 minute venules, the intralobular veins, in the centre of each lobule ; these 

 pour their blood into larger vessels, the sublobular veins ; and the sublo- 

 bular veins constitute, by their convergence and union, the hepatic trunks, 

 which terminate in the inferior vena cava. 



