140 Anatomy Applied to Medicine and Surgery. 



etc.; (2) downwards, from hypertrophy of the right ven- 

 tricle, or from depression of the diaphragm ; (3) towards 

 the left, from dilitation and hypertrophy of the ventricles, 

 or, from right-sided pleural effusions, or, left-sided pleu- 

 ral contraction, i.e., retraction; (4) towards the right, 

 'from left-sided effu'sions, or from right-sided retractions. 

 Percussion. Heart. On percussing from above 

 downwards, in a line immediately to the left of the ster- 

 num, the resonance begins to change about the lower bor- 

 der of the third costal cartilage. The note yielded from 

 this point, down to the lower level of the fourth costal 

 cartilage, is termed "relative cardiac dullness" and cor- 

 responds to the underlying heart covered by a thin layer 

 of lung tissue, while immediately below the fourth car- 

 tilage, on this side, the note becomes completely dull "ab- 

 solute cardiac dullness." This area, of absolute dullness, 

 merges, below, into the dullness arising from the liver. 

 To define the right limit of cardiac dullness, percuss, by 

 placing the ringer vertically on the right side of the tho- 

 rax, beginning at the mammary line about the level of the 

 fifth rib, and working in towards the sternum. To define 

 the left limit, begin at the left coracoid line and percuss 

 inwards, towards the sternum. In the normal heart the 

 note will begin to change, a little to the inner side of the 

 mammary line, at which point the area of "relative car- 

 diac dullness" begins. This area of "relative" or super- 

 ficial cardiac dullness merges into the area of "absolute" 

 or deep cardiac dullness at a point about an inch inside of 

 the mammary line, and the area of "absolute dullness" 

 corresponds, roughly, to a circle two inches in diameter 

 drawn around a point midway between the nipple and the 

 lower end of the gladiolus. "Absolute cardiac dullness" 

 is generally diminished in emphysema, but increased in 

 hypertrophy and in those diseases in which the lung is re- 



