THE CHEST. 19 



THE CHEST. 



33. As a rule, the right half of the chest is slightly larger 

 than the left. Of ninety-two persons of the male sex and 

 good constitutions, seventy-one had the right side the larger ; 

 eleven the left ; ten had both sides equal. The maximum of 

 difference in favour of the right was one inch and a quarter. 

 The measurements were made on a plane with the nipple. 



34. Peculiarities in the female. The chest of the 

 female differs from that of the male in the following points : 

 Its general capacity is less ; the sternum is shorter ; the upper 

 opening is larger in proportion to the lower ; the upper ribs 

 are more movable, and therefore permit a greater enlarge- 

 ment of the chest at its upper part, in adaptation to the 

 requirements of pregnancy. 



35. The top of the sternum is on a level with the second 

 dorsal vertebra ; and the available space between the top of 

 the sternum and the spine is hardly more than two inches. 2 



36. Parts behind first bone of sternum. There is 

 little or no lung behind the first bone of the sternum, the 

 space being occupied by the trachea and large vessels as 

 follows : 



The left vena innominata crosses the sternum just below 

 the upper border. Next come the great primary branches of 

 the arch of the aorta. Deeper still is the trachea dividing 

 into its two bronchi opposite the junction of the first and 

 second bones of the sternum. Deepest of all is the ceso- 

 phagus. 



About one inch from the upper border of the sternum is 

 the highest part of the arch of the aorta, which lies on the 

 bifurcation of the trachea. 



37. The course of the arteria innominata corresponds 

 with a line drawn from the middle of the junction of the first 

 with the second bone of the sternum, to the right sterno- 

 clavicular joint. When the artery rises higher than usual 

 into the neck, its pulsation can be felt in the fossa above the 

 sternum. 



38. Rules for counting- the ribs. In fat persons it is 



