The study of heart sounds and cardiac murmurs, with reference to their diagnosis by physical signs, requires an accurate knowledge of the anatomy, and physiological mechanism of the heart.
By heart sounds we mean the normal sounds produced by the action of the heart,while new or additional or adventitious sounds are called cardiac murmurs. Murmurs are not modifications of the normal heart sounds, but are new sounds, which are added to,or take the place of the normal sounds,on account of mechanical defects in the action of the heart. These mechanical defects are usually the results of pathological lesions.
The praecardial region or prœcardia, is that part of the surface of the chest, which immediately overlies the heart. The upper boundary of this space, which corresponds to the base of the heart, is a horizontal line drawn across the sternum at the level of the third costal cartilage. The lower boundary