What is the main function of the muscular diaphragm?

Answer 1

Your diaphragm is a thin broad muscle that separates your thoracic cavity from your abdominal cavity. The mechanics of breathing, that is physiological breathing are based on a negative pressure system. At rest the diaphragm has a concavity inferiorly towards the abdominal cavity, in order to draw air in from the atmosphere the diaphragm contracts, flattening out increasing the space in the thoracic cavity and thus drawing air in from an area of high pressure to low pressure or from the atmosphere into the lung tissue.

Main function: respiration

Secondary function: separate contents of abdominal and thoracic cavities

Answer 2

Muscular diaphragm is essential for us to breath. We need it to breathe in. When we breathe in, the diaphragm inferiorly which expand the thoracic cavity. When the thoracic cavity is expanded, the lungs volume increase which change the pressure inside which help us draw the air into the lungs. We do not normally use our diaphragm for breathing out, however, with one exception -- forceful breath out (breath out after you take in a deep breath and breath out completely, the diaphragm gently push up and assist pushing air out tiny bit.