What is the medical term for tapping on a surface to determine the density of the underlying structure?

• A. Auscultation
• B. Palpation
• C. Percussion
• D. Proctosigmoidoscopy

Answer: (C)

Percussion is the tapping technique used to infer what lies beneath the surface by the sound and vibration it produces. By tapping with a finger and listening to the pitch and quality of the sound, a clinician can distinguish air-filled from fluid-filled or solid structures. A resonant sound suggests air, a dull sound indicates dense tissue or fluid, and tympanic sounds point to gas-filled spaces. This method helps estimate organ size and detect abnormalities such as fluid in the chest or abdomen. Auscultation involves listening with a stethoscope, palpation is feeling with the hands, and proctosigmoidoscopy is a visual inspection with a scope of the rectum and sigmoid colon.