THE HEART-SOUNDS. 



93 



Pig. 31. 



The heart its several parts and great vessels in relation to the front of the 

 thorax. The lungs are collapsed to their normal extent, as after death, 

 exposing the heart. The outlines of the several parts of the heart are indi- 

 cated by very fine dotted lines. The area of propagation of valvular murmurs 

 is marked out by more visible dotted lines. A, the circle of mitral murmur, 

 corresponds to the left apex. The broad and somewhat diffused area, roughly 

 triangular, is the region of tricuspid murmurs, and corresponds generally with 

 the right ventricle, where it is least covered by lung. The letter C is in its 

 centre. The circumscribed circular area, D, is the part over which the pulmonic 

 arterial murmurs are commonly heard loudest. In many cases it is an inch, 

 or even more, lower down, corresponding to the conus arteriosus of the right 

 ventricle, where it touches the walls of the thorax. The internal organs and 

 parts of organs are indicated by letters as follows r. au, right auricle, 

 traced in fine dotting ; ao, arch of aorta, seen in the first intercostal space, 

 and traced in fine dotting on the sternum ; vi, the two innominate veins j 

 rv 3 right ventricle ; lv, left ventricle. 



