Diaphragm: The major muscle of inspiration (inhalation). The dome-shaped sheet of skeletal muscle that separates the abdomen from the thoracic cavity (area within ribs). The convexity of the muscle points upward into the thoracic cavity and it contracts with each inspiration, causing it to flatten downward so that the base of the lungs are permitted to descend into the abdominal cavity and fully inflate. The muscle relaxes with expiration (exhalation) and elevates back into the thoracic cavity. See the breathing category or more about the diaphragm.
This page created 04 Oct 2011 01:21
Last updated 01 Mar 2016 00:05