A stethoscope is an instrument for listening to sounds of the heartbeat, lungs, blood circulating in vessels, and other internal sounds via vibration. It can be used both to listen to a patient's heart and lungs as well as by physicians during exams. A stethoscope typically consists of at least one pair of U-shaped tubes that are placed on the chest wall, with their bell ends positioned between the collarbones or around the region of the lower neck. Air pressure inside these tubes causes them to vibrate when they are placed on a patient's chest.
