ANATOMY OF THE HEART 153 



ting away front of chest with scissors, the relation of 

 diaphragm, heart, lungs, trachea and esophagus. 



2) Expose trachea in neck, cut, and insert glass tube, tying 

 on if necessary. Inflate lungs to natural size, and note their 

 relations to ribs, heart, diaphragm and abdominal organs. 



3) Carefully manipulate heart and lungs : 



a) Find vena cava inferior on under (abdominal) side of 

 diaphragm ; thence follow it until it enters pericardium. 



b) Trace out veins which vena cava inferior receives from 

 liver, spleen, kidneys and diaphragm. 



c) Trace out superior vena cava and its branches. 



d) Notice between ends of two venas cavae the right pul- 

 monary veins proceeding from lung and entering pericardium. 



4) Turn lung and heart back to their natural positions. 

 Trace out aorta, its arch and branches ; pulmonary artery dor- 

 sal to aorta, and its branches into lungs ; pulmonary veins. 



5) Slit open pericardial sac. 1 Note character of lining mem- 

 brane of cavity ; and character and amount of fluid present. 



6) Cut away pericardium carefully from various vessels at 

 base. Note general form and position of heart and location of 

 vessels connected with its base. 



7) Carefully dissect out entrance of pulmonary veins into 

 heart. 2 Note on exterior the left and right auricles; the band 

 of fat running around top of ventricles and its offshoot running 

 obliquely down front of heart, thence passing to right of its 

 apex. ( This indicates position of partition, or septum, between 

 two ventricles.) 



8) Dissect away fat around origins of great arterial trunks 

 and around base of ventricles. In fat will be found two 

 coronary arteries arising from aorta close to heart, and the 

 coronary veins which accompany them. 



9) Open right ventricle by passing blade of scalpel through 

 its wall about 1 in. from upper border of ventricle and on right 

 of band of fat, and cut down toward apex. Make a correspond- 

 ing cut through wall of same venticle on its other side. Raise 



1 The following dissections are much better carried out upon the 

 sheep's heart owing to its larger size. 



2 It will probably seem as if the right pulmonary veins and the 

 inferior cava opened into the same auricle, but it will be found 

 subsequently, (14), that such is not really the case. 



