324 



THE HUMAN BODY 



but turned the other way, its broad part being lowest and 

 attached to the upper surface of the diaphragm. Internally it is 

 lined by a smooth serous membrane like that lining the abdominal 

 cavity, and a similar layer (the visceral layer of the pericardium) 



mdu 



del 



mva 



mvp 



imv 



FIG. 100. The arteries of the hand, showing the communications or anasto- 

 moses of different arteries and the fine terminal twigs given off from the larger 

 trunks; these twigs end in the capillaries which would only become visible if mag- 

 nified. R, the radial artery on which the pulse is usually felt at the wrist; U, the 

 ulnar artery. 



covers the outside of the heart itself, adhering closely to it. Each 

 of the serous layers is covered by a stratum of flat cells, and in the 

 space between them is found a small quantity of liquid which 

 moistens the contiguous surfaces, and diminishes the friction which 

 would otherwise occur during the movements of the heart. 



Internally the heart is also lined by a fibrous membrane, covered 

 with a single layer of flattened cells, and called the endocardium. 



