THE VASCULAR SYSTEM 



151 



left atrioventricular opening is guarded by the bicuspid or 

 mitral valve. These valves may be displayed by cutting away 

 the caudal half of the ventral wall of the ventricles, when the 



Fig. 74. — Photograph of the Ven- 

 tral Aspect of the Human Heart 

 Injected. 



a. Aorta; b, left ventricle; c, carotid 

 arteries; d, right ventricle; e, esophagus; 

 I, left atrium; n, right atrium; s, sub- 

 clavian artery; t, trachea; v, superior 

 vena cava. H natural size. 



W 



Fig. 75. — Heart Viewed Ven- 

 trally, with Ventral Half of 

 THE Atria and Ventricles Cut 

 Away and the Atria Drawn 

 Laterad. Partly diagrammatic. 



a. Orifice of the aorta; ao, aorta; 

 aao, arch of the aorta; ap, orifice of 

 the precava; as, orifice of the post- 

 cava; Iv, left pulmonary veins; Ivn, 

 left ventricle; mi, mitral or bicuspid 

 valve; la, left atrium; -p, orifice of 

 the pulmonary veins; pc, inferior 

 vena cava; pre, superior vena cava; 

 ha, orifice of the pulmonary artery; 

 pYV, right pulmonary veins; rv, right 

 ventricle and one of the right pul- 

 monary veins; ra, right atrium; rp, 

 right pulmonary artery; Ir, tricuspid 

 valve; xp, left pulmonary artery. 



chordcz tendinecE, delicate tendinous cords, will be seen extend- 

 ing from the margins of the translucent membranous valves 

 to the trabecuLT carnese or muscular projections on the walls 



