VALVES OF THE HEART 139 



offer no resistance to the movement of the blood from 

 the auricles into the ventricles. Because these valves 

 lie between the auricles and the ventricles, they are called 

 the auricula-ventricular valves. 



Exit valves from ventricles. Leading from each 

 ventricle is a large artery. At the beginning of each 



Superior vena cava 

 Pulmonary artery 



Valve flap 



Left auriclfr 

 Wall of right auricle 

 Coronary artery 



Right auriculo- 



ventricular valve 



Tendinous cords 

 Papillary muscles 



Wai! of right 



ventricle 

 Inferior vena cava- 



Left ventricle 



FIG. 81. Heart, with portion of right auricle and right ventricle cut away to show 

 interior. Bristles show passage ways. 



of these two arteries, there is also a valve to prevent the 

 blood from flowing back into the relaxed ventricle. 

 Each valve consists of three thin tough pockets, or valve 

 flaps, which lie flat against the walls of the artery when 



