250 CLINICAL APPLIED ANATOMY. 



extremity of the upper border to the impulse. This line is 

 convex outwards, and at the level of the fourth left costal 

 cartilage lies three inches to the left of the mid-line of the 

 sternum. The right border, corresponding to the right auricle, 

 is represented by a line, convex to the right, drawn from the 

 right extremity of the upper border to the sixth right costal 

 cartilage near the sternum. This line extends an inch and a half 

 to the right of the mid-sternal line at the level of the fourth 

 costal cartilage. The lower border, or margoacutus of the right 

 ventricle, extends from the sixth costal cartilage of the right side 

 to the impulse. This line passes to the left with slight down- 

 ward obliquity, crossing the sternum at the base of the ensiform 

 cartilage. 



A line drawn obliquely across the cardiac area from the lower 

 border of the left third to the right sixth costal cartilage, com- 

 mencing at the mid-line of the sternum and terminating at the 

 right edge, indicates the furrow between the right auricle, which 

 lies above and to the right, and the ventricles which lie below 

 and to the left. The leftmost strip of the cardiac area, nearly 

 an inch broad, commencing at the lower border of the third left 

 costal cartilage and terminating at the impulse, represents the 

 anterior part of the left ventricle. Immediately above the left 

 ventricular strip lies the left auricular appendix. 



The heart is in contact laterally with resonant lung, and 

 wedge-shaped portions of pulmonary tissue also pass forwards 

 between its anterior surface and the chest wall. These wedge- 

 shaped prolongations gradually thin off and leave uncovered the 

 lower part of the anterior surface of the right ventricle. The 

 part uncovered corresponds to the area of superficial cardiac 

 dulness. The area is limited above by the fourth left costal 

 cartilage, internally by the left edge of the sternum, and 

 externally by an oblique line starting from the fourth left costal 

 cartilage in the parasternal line and passing thence to the 

 position of the cardiac impulse. This area is dull to light per- 

 cussion, and can be easily determined. The deep cardiac dulness 

 which should correspond to the actual outline of the heart 



