28 



TOPOGRAPHICAL ANATOMY OF THE 



apex, it is clear, even on an external examination, that the apex of the 

 heart is formed by one ventricle only, namely, the left. 



The cranial border (margo crauialis) of the heart is gently convex 

 and mainly formed by the right ventricle. Tlie caudal border (margo 

 caudalis), formed entirely by the left ventricle, is convex in its dorsal 

 half and slightly concave towards the apex of the heart. 



A. coronaria dextra. 



Pulmonary 

 semilunar valves. \^ 



Tricuspid valve. 



sAortic scmilunaii 

 valves. ! 



Bicuspid valve. 



Fig. 12. — The base of the ventricles of the heart. Tlie atria have been removed 

 to show the arrangement of the valves. 



Dissection. — The vessels and nerves that supply the tissues of the 

 wall of the heart should now be dissected. In order to do this, it is 

 necessary to remove the epicardium and the sulijacent fat from the 

 grooves. The remains of the pericardium should also be cleared away. 



The wall of the heart is supplied with blood by the two coronary 

 arteries, right and left, and is drained by the great cardiac, the middle 

 cardiac, and a number of small cardiac veins. 



