212 THE HUMAN BODY. 



below named until they enter the pericardium. Be very careful not 

 to cut the veins, which, being thin, collapse when empty, and may 

 be easily overlooked until injured. As each vein is found stuff it 

 with raw cotton, which makes its dissection much easier. 



a. The vena cava inferior : find it on the under (Abdominal) side of 

 the diaphragm ; thence follow it until it enters the pericardium, about 

 three inches further up; to follow it in this part of its course, turn 

 the right lung towards your left and the heart towards your right. 



The vein just below the diaphragm, may be seen to receive several 

 large vessels, the hepatic veins. 



As it passes through the midriff, two veins from that organ enter it. 



Between diaphragm and pericardium the inferior cava receives no 

 branch; but, lying on its left side, will be seen the lower end of the 

 right phrenic nerve, ending below in several branches to the diaphragm. 



b. Superior vena cava : seek its lower end, entering the pericardium 

 about one inch above the entry of the inferior cava; thence trace it 

 up to the point where it has been cut across; stuff and clean it. 



c. Between the ends of the two venae cavse will be seen the two 

 right pulmonary veins, proceeding from the lung and entering the 

 pericardium; clean and stuff them. 



5. Turn the right lung and the heart back into their natural posi- 

 tions; clear away the loose fat in front of the pericardium, and seek 

 and clean the following vessels in the mass of tissue lying anterior to 

 the heart, and on the ventral side of the windpipe. 



a. The aorta : immediately on leaving the pericardium this vessel 

 gives off a large branch; it then arches back and runs down behind 

 the heart and lungs, giving off several branches on its way. 



6. The pulmonary artery : this will be found imbedded in fat on 

 the dorsal side of the aorta. After a course, outside the pericardium, 

 of about an inch, it ends by dividing into two large branches (right 

 and left pulmonary arteries), which subdivide into smaller vessels as 

 they enter the lungs. 



c. Observe the thickness and firmness of the arterial walls as 

 compared with those of the veins; they stand out without being 

 stuffed. 



6. Notice, on the ventral side of the left pulmonary artery, the 

 left pulmonary veins passing from the lung into the pericardium. 



7. Up to this point the dissection may be made before the meeting 

 of the class; on the preparation demonstrate the anatomical facts 

 above noted and then proceed as follows: 



8. Slit open the pericardiac bag, and note its smooth, moist, glis- 

 tening inner surface, and the similar character of the outer surface of 

 the heart. Cut away the pericardium carefully from the entrances 

 of the various vessels which you have already traced to it. As this 



