Apex

(a’-peks) [apex, the extreme end of a thing]. The summit or top of anything; the point or extremity of a cone. A. Beat, the impulse of the heart felt in the fifth intercostal space, about 3^ inches from the middle of the sternum. A. Murmur, a murmur heard over the apex of the heart. A. of the Lung, the upper extremity of the lung behind the border of the first rib. 71