The Diaphragm: Your Key Muscle for Breathing - Anatomy & Function

Diaphragm

The diaphragm is the primary muscle of respiration. It is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. When the diaphragm contracts, it pulls the lungs downward, creating a negative pressure in the chest cavity. This negative pressure causes air to flow into the lungs. When the diaphragm relaxes, the lungs recoil and air flows out.

The diaphragm is also involved in coughing, sneezing, and vomiting.