402 DISSECTION OF THE ABDOMEN. 



The VENA CAVA INFERIOR (fig. 171, w) collects and conveys to the 

 heart the blood of the lower halt of the body. Taking the origin on the 

 right side of the fifth lumbar vertebra, below the bifurcation of the aorta, 

 this large vein ascends on the right side of the vertebral column, and 

 reaches the heart by perforating the diaphragm. Its connections with the 

 surrounding parts have been already noticed (p. 444), but the description 

 may be referred to, as the position of the branches of the aorta to it can 

 be better seen now. 



Branches. The cava receives parietal branches (lumbar and dia- 

 phragmatic), from the wall of the abdomen and the diaphragm ; and vis- 

 ceral branches from the testicle, the kidney, the suprarenal body, and the 

 liver. 



The veins belonging to the digestive apparatus, viz., the intestinal canal, 

 the spleen, and the pancreas, are united to form the vena portre (p. 448) ; 

 and the blood contained in those veins reaches the cava by the venae cava? 

 hepatic, after it has circulated through the liver. 



The spermatic vein (fig. 171, 0) enters the abdomen by the internal 

 abdominal ring, after forming the spermatic plexus in the cord (p. 484). 

 At first there are two branches in the abdomen, which lie on the sides of 

 the spermatic artery; but these soon join into one trunk. On the left 

 side it opens into the renal vein at right angles, and a small valve exists 

 sometimes over the aperture ; on the right side it enters the inferior cava 

 below the renal vein. As the vein ascends to its destination, it receives 

 one or more branches from the wall of the abdomen, and from the fat 

 about the kidney. 



In the female this vein (ovarian) has the same ending as in the male, 

 and it forms a plexus in the broad ligament of the uterus. Valves are 

 absent from the vein and its branches, but occasionally there is one at its 

 union with the renal. 



The renal or emulgent vein (fig. 171, ri) is of large size, and joins the 

 vena cava at a right angle. It commences by many branches in the kid- 

 ney; and the trunk resulting from their union is superficial to the renal 

 artery. 



The right is the shortest, and joins the cava higher up usually than the 

 other. The left vein crosses the aorta close to the origin of the superior 

 mesenteric artery : it receives separate branches from the left spermatic 

 and suprarenal veins. 



The suprarenal vein is of considerable size when it is compared with 

 the body from which it comes. The right opens into the cava, and the 

 left into the renal vein. 



The hepatic veins enter the vena cava where it is in contact with the 

 liver. These veins are described in the dissection of the liver (p. 468). 



The lumbar veins correspond in number and course with the arteries of 

 the same name: they will be dissected after. 



The diaphragmatic veins (inferior), two with each artery, spring from 

 the under surface of the diaphragm. They join the cava either as one 

 trunk or two. 



DEEP MfSCLES OF TIIK AP.HO.MKN. 



The deep muscles in the interior of the abdomen are the psoas, iliacus, 

 and rjuadratus lumborum. 



The PSOAS MAfixrs (fig. 171, F ) reaches from the lumbar vertebras to 

 the femur, and is situate partly in the abdomen and partly in the thigh. 



