THE ARTERIES. 



209 



mer vessel. The pulmonary artery only carries blood to 

 the lungs to undergo exchanges with the air in them, after 

 it has circulated through the Body generally. 



After making its arch the aorta continues back through 



JIpl 



Mpm 



FIG. 81. The left ventricle and the commencement of the aorta laid open. 

 Mpm, Mpl, the papillary muscles. From their upper ends are seen the cordce 

 tendinece proceeding to the edges of the flaps of the mitral valve. The open- 

 ing into the auricle lies between these flaps. At the beginning of the aorta are 

 seen its three pouch-like semilunar valves. 



the chest, giving off many branches on its way. Piercing 

 the diaphragm it enters the abdomen and after supplying 

 the parts in and around that cavity with branches, it ends 



