EXTERIOR OF THE HEART. 



205 



left auricle and ventricle, each auricle communicating by 

 an auricula- ventricular orifice with the ventricle on its own 

 side, and there is no direct communication whatever through 

 the septum between the opposite sides of the* heart. To 

 get from one side to 'the other the blood must leave the 



Ade 



Asi 



FIG. 79. The heart and the great blood-vessel attached to it, seen from the 

 side towards the sternum. The left cavities and the vessels connected with 

 them are colored red; the right black. Ats, left Auricle ; Adx and As, the right 

 and left auricular appendages ; Vd, right 1 ventricle ; Vs, left ventricle ; Aa, 

 aorta ; Ab, innominate artery ; Cs, left common carotid artery; Ssi, left sub- 

 clavian artery ; P, main trunk of the pulmonary artery,- and Pd and Ps, its 

 branches to the right and left lungs ; c-s, superior vena cava ; Ade and Asi, the 

 right and left innominate veins ; pd and ps, the right and left pulmonary veins; 

 crd and crs, the right and left coronary arteries. 



heart and pass through a set of capillaries, as may readily 

 be seen by tracing the course of tlio vessels in Fig. 76. 



The Heart as seen from, its Exterior. When the heart 

 is viewed from the side turned towards the sternum (Fir. 

 79) the two auricles, Aid and As, are seen to be separated 



