CHAPTER XIV. 



THE HEART. 



ANATOMY. LANDMARKS. 



CLINICAL EXAMINATION OF HEART AND LUNGS. 

 PERCUSSION. CARDIAC NEUROSES. 



The heart is contained in the pericardium and consists 

 of a base directed upwards and backwards towards the fifth, 

 sixth, seventh and eighth dorsal vertebrae, and an apex, 

 downwards and forwards, towards the ribs. This position 

 of the axis of the heart causes the anterior surface to be 

 directed upwards and forwards, and the posterior surface, 

 which rests on the pericardium where it is attached to the 

 diaphragm, to be directed downwards and backwards. 

 The heart measures five inches in length, three and a half 

 inches in breadth and two and a half inches in thickness, 

 and is so situated that it extends one and a half inches to 

 the right and three and a half inches to the left of the mid- 

 dle line of the sternum. The walls of the right auricle 

 are thinner than those of the left auricle, whereas the left 

 ventricle, having to propel the blood a greater distance 

 than the right, is much thicker than the latter. Grooves 

 on the surfaces of the heart, indicate the separation of the 

 auricles from the ventricles and the ventricles from 

 each other, thus the auricles are separated from the ven- 

 tricles by the auriculo-ventricular grooves, and the ven- 

 tricles from one another by the interventricular grooves. 

 The anterior surface is composed mainly of the right 

 ventricle, with the right auricle on its right, and the left 

 ventricle on its left, while the very small portion of the 

 left auricle exposed, lies above the left ventricle. The 

 posterior surface, where it rests on the diaphragm, is 

 formed by both right and left ventricles, the latter, how- 

 ever, constituting the chief part of this surface. 



