

CIRCULATION. THE HEART. 



135 



muscular powers. In fact, a large number of papillary 

 muscles, having as many as 100 tendons in the right heart, 

 and 120 in the left, are inserted in the edges and external 

 surface of this auriculo-ventricular apparatus. When the 

 ventricle contracts, these papillary muscles also come into 

 play. It was formerly supposed that these muscles and the 

 tendons belonging to them must serve to prevent the sup- 

 posed valve from being too much stretched in consequence of 

 a retrograde effort of the blood, and from being turned wrong 

 side out in the auricular cavity. But their function is entirely 

 different, for if the finger be introduced into the auriculo- 

 ventricular region at the moment of the systole of the ven- 

 tricle, we find that the kind of funnel which hangs from the 

 auricle to the ventricle is continued; it even appears to 



Fig 38. Showing the auriculo- 

 ventricular system daring the 

 repose of the ventricle.* 



39. Showing the auriculo-ventricu- 

 ir apparatus during the contraction 

 of the veutricle.f 



lengthen itself out, and the finger, as it were, is drawn into 

 the interior of the ventricle. In fact, the first result of the 

 contraction of the papillary muscles is the lengthening of 

 the auricular cone, the edges of which are afterwards brought 

 near each other. While this hollow cone descends into the 

 ventricle, the sides of the latter contract, and approach the 

 cone in such a manner that the auriculo-ventricular apparatus 

 acts as a sort of hollow piston, which penetrates the ventri- 

 cle and comes into close contact with its walls, and thus the 



* V, Vein. 0, Auricle. V, Coats of the ventricle, with the papillary 

 muscles and their tendons. A, Artery. 1, Cavity of the auriculo-ventricular 

 apparatus. 2, Infundibulura. 



t 1, During the first half of the ventricular systole. 2, At the end of this 

 ystole. A V, The hollow piston formed bv the auriculo-ventricular apparatus. 

 O Auricle. V, Coats of the ventricle. A, fulmonary artery and (arterial) aorta. 



