LIMITS OF THE LUNGS. 



243 



both lungs reach as far down as the tenth rib. During the deepest 

 inspiration, the lungs descend anteriorly as far as between the sixth and 

 seventh ribs, and posteriorly to the eleventh rib whereby the 

 diaphragm is separated from the thoracic "wall (Fig.' 105). During the 

 deepest expiration, the lower margins of the lungs are elevated almost 

 as much as they descend during inspiration. In Fig. 109, m, n, indicates 

 the margin of the right lung during deep inspiration ; h, I, during deep 

 expiration. 



It is important to observe the relation of the margin of the left lung 



Fig. 109. 



Topography of the lungs and heart during inspiration and expiration (v. Dusch) . 

 A, I, upward limit of margin of lung during deepest expiration; m, n, lower 

 limit during deepest inspiration; t, t', t", triangular area where the heart is 

 uncovered by lung, dull percussion sound; d, d', d", muffled percussion 

 sound; i, i', anterior margin of left lung reaches this line during deep inspira- 

 tion, and during deep expiration it recedes as far as e, e'. 



to the heart. In Fig. 109, a somewhat triangular space, reaching from 

 the middle of the point of insertion of the fourth rib to the sixth rib on 

 the left side of the sternum, is indicated. In the passive chest, the heart 

 lies in contact with the thoracic wall in this triangular area. This area 

 is represented by the triangle, t, t', t", and percussion over it gives a 

 dull sound (superficial dulness). 



In the area of the larger triangle, d, d", d", where the heart is 



