316 DISSECTION OF TIffi EABBIT 



down the lieck alongside the trachea, to open 

 into the external jugular vein close to its 

 union with the subclavian. 



b. The left anterior vena cava resembles the right, 



except that it receives no azygos vein, and that 

 its course in the thorax is somewhat different, eis 

 already described (p. 313). 



c. The posterior vena cava is a large median vein, com- 



mencing at the hinder end of the abdomen, and 

 running forwards close to the vertebral column 

 and to the right of the aorta. In front, it leaves 

 the abdominal wall and becomes imbedded in the 

 dorsal surface of the liver, beyond which it enters 

 the thorax through an aperture in the central 

 tendon of the diaphragm, and runs forwards, as 

 already described (p. 313), to open into the right 

 auricle. 



The following are the principal veins opening 

 into the vena cava. 



In dissecting these veins, take care not to damage the 

 arteries, which accompany and roughly correspond to them, 

 or the urinary and genital organs. 



i. The phrenic veins are small veins in the substance 



of the diaphragm, opening into the vena cava 



as it passes through. 



ii. The hepatic veins are large vessels returning 



blood from the several lobes of the liver, and 



opening into the portion of the vena cava 



imbedded in the liver. There are four chief 



ones. 



To see the hepatic veins, ligature the vena cava, both in 



front of and behind the liver : cut across the vena cava, 



remove the Uver, and lay it on the dissecting -board with the 



dorsal surface upwards : sUt open the vena cava ; wash out 



the contained blood ; note the openings of the hepatic veins, 



and follow these with a seeher into the several iobes of the 



liver. 



