PHYSIOLOGICAL ANATOMY OF THE HEART 



35 



the opening into the left auricle. After birth the foramen ovale is closed 

 and the Eustachian valve gradually disappears. 



The ventricles, in the human subject and in warm-blooded animals, 

 constitute the bulk of the heart. They have a capacity somewhat greater 

 than that of the auricles and are provided with thick muscular walls. 

 The action of this portion of the heart sends the blood, on the one 

 hand, to the lungs and 

 back to the left side of 

 the heart, and on the 

 other, through the en- 

 tire system of the greater 

 circulation, to the right 

 side. 



The capacity of the 

 cavities in the right side 

 of the heart is one-tenth 

 to one-eighth greater 

 than that of the corre- 

 sponding cavities on the 

 left side. The capacity 

 of the ventricles exceeds 

 that of the auricles by 

 one-fourth to one-third. 

 The absolute capacity of 

 the left ventricle, when 

 distended to its utmost, 

 is 4.8 to 7 ounces (143 to 

 212 cubic centimeters). 

 This is much greater 

 than most estimates, 

 which place the capacity 



Fig. 18. Heart, anterior view (Bonamy and Beau). 



r i r ,i . I, right ventricle ; 2, left ventricle ; 3, Bright auricle ,-5,6, left 



ine VariOUS auricle; 7, pulmonary artery; 8, aorta; 9, superior vena cava ; 



Cavities moderatelv dis- I0> an terior coronary artery; n, branch of the coronary vein; 



, . , 12, 12, 12, lymphatic vessels. 



tended, at about three 



ounces (90 cubic centimeters). Notwithstanding the disparity in the 

 extreme capacity of the various cavities, the quantity of blood which 

 enters these cavities necessarily is equal to that which is expelled. 

 This is estimated at about three ounces (90 cubic centimeters). 



The cavities of the ventricles are conoidal, the right being broader 

 and shorter than the left, which latter extends to the apex. The inner sur- 

 faces of both cavities are marked by ridges and papillae, called columnae 

 carneae. Some of these are fleshy ridges projecting into the cavity; 



