22 



LANDMARKS MEDICAL AND SURGICAL. 



rounded off) shows that the apex of the heart points down- 

 wards and towards the left, the base a little upwards and 

 towards the right ; that the greater part of it lies in the left 

 half of the chest, and that the only part which lies to the 

 right of the sternum is the right auricle. A needle intro- 

 duced in the third, the fourth, or the fifth right intercostal 

 space close to the sternum would penetrate the lung and the 

 right auricle. 



A needle passed through the second intercostal space, 

 close to the right side of the sternum, would, after passing 

 through the lung, enter the pericardium and the most promi- 

 nent part of the bulge of the aorta. 



A needle passed through the first intercostal space, close 

 to the right side of the sternum, would pass through the lung 

 and enter the superior vena cava above the pericardium. 



OUTLINE OF THE HEART, ITS VALVES, AND THE LUNGS. 



42. The best definition of that part of the praecordial 

 region which is less resonant on percussion, was given by 



