ABDOMINAL CAVITY 543 



present they are only seen in a very short part of their course. 

 They proceed laterally upon the bodies of the upper four 

 lumbar vertebrae, behind the gangliated cord of the sym- 

 pathetic, and then disappear under cover of the psoas magnus 

 muscle and the series of fibrous arches from which the 

 muscle arises. The two upper arteries also pass behind the 

 crura of the diaphragm, and on the right side they pass 

 behind by the inferior vena cava. 



The lumbar veins join the inferior vena cava, and those of 

 the left side pass behind the aorta. 



Vena Cava Inferior. This is the large vein which collects, 

 by means of its tributaries, the venous blood from the lower 

 limbs, the abdominal viscera, and a great part of the abdominal 

 parietes. It is formed in front of the body of the fifth lumbar 

 vertebra, to the right of the median plane, by the union of the 

 two common iliac veins. As it ascends it lies at first at the 

 right side of the aorta in front of the bodies of the vertebrae 

 and the medial part of the right psoas magnus, but it is separ- 

 ated from the vertebral bodies by the anterior longitudinal 

 ligament and the lower right lumbar arteries, and from the 

 anterior border of the psoas magnus by the right sympathetic 

 cord. Above the lower border of the second lumbar vertebra 

 it is separated from the aorta by the right crus of the diaphragm. 

 The right renal artery, the right cceliac ganglion, the right 

 inferior phrenic artery, the right suprarenal artery, and the 

 medial part of the anterior surface of the right suprarenal 

 gland intervene between it and the crus. At its commence- 

 ment it lies behind the right common iliac artery, then it is 

 crossed by the root of the mesentery and the superior 

 mesenteric vessels. For a short distance above the root of 

 the mesentery it is in direct relation with the peritoneum on 

 the posterior wall of the great sac. At the level of the third 

 lumbar vertebra it is crossed by the third part of the duo- 

 denum and the right internal spermatic or ovarian artery. 

 Next the head of the pancreas and the pancreatico-duodenal 

 arteries are in front of it and the bile-duct descends in front 

 of its lateral border. Above the head of the pancreas it 

 passes behind the first part of the duodenum, from which it is 

 separated by the portal vein, then it ascends behind the epi- 

 ploic foramen, and finally it lies in the vena caval fossa on 

 the posterior surface of the liver and the hepatic veins open 

 into the uppermost part of its anterior surface. 



