Percussion is a method of tapping on a surface to determine the underlying structures, and is used in clinical examinations to assess the condition of the thorax or abdomen.
It is one of the four methods of clinical examination, together with inspection, palpation, auscultation, and inquiry.
When percussing boney areas such as the clavicle, the pleximeter can be omitted and the bone is tapped directly such as when percussing an apical cavitary lung lesion typical of tuberculosis.
A dull sound indicates the presence of a solid mass under the surface.
Percussion was at first used to distinguish between empty and filled barrels of liquor, and Dr. Leopold Auenbrugger is said to be the person who introduced the technique to modern medicine, although this method was used by Avicenna about 1000 years before that for medical practice such as using percussion over the stomach to show how full it is, and to distinguish between ascites and tympanites.