Diaphragm & Rib Cage: How They Facilitate Exhalation

Diaphragm:

The diaphragm is the primary muscle responsible for breathing. It sits just below the lungs and plays a crucial role in exhalation. When the diaphragm contracts, it moves downwards, increasing the volume of the thoracic cavity. This creates negative pressure, causing air to be forced out of the lungs.

Rib Cage:

The rib cage consists of ribs and intercostal muscles that surround the thoracic cavity. During inhalation, the intercostal muscles contract, elevating the rib cage and expanding the thoracic cavity. However, during exhalation, the intercostal muscles relax, allowing the rib cage to recoil back to its resting position. This downward movement of the rib cage further increases the volume of the thoracic cavity, forcing air out of the lungs.

The coordinated relaxation of the intercostal muscles and the upward movement of the diaphragm also reduce the size of the thoracic cavity, increasing pressure within the lungs and facilitating the flow of air out.