The diaphragm is the body?s primary breathing muscle. With each inhalation, the diaphragm expands the chest, allowing the lungs to take in air. The ribs and intercostal muscles support breathing by helping the chest cavity expand and contract. The rib cage protects the lungs and heart as well.
The diaphragm is a dome-shaped muscle that separates the chest and abdominal cavity. With each inhalation, the diaphragm tightens and moves downward, causing the suction that allows the lungs to expand. The intercostal muscles also contract and elevate the rib cage, expanding the chest cavity. During exhalation, the diaphragm and intercostal muscles relax, decreasing the size of the chest cavity.