The primary muscle responsible for pulmonary ventilation is the diaphragm.
The diaphragm is a dome-shaped muscle that separates the chest cavity from the abdominal cavity. When the diaphragm contracts, it moves downward, creating a vacuum that allows air to be drawn into the lungs. This process is critical for inhalation. During exhalation, the diaphragm relaxes and moves back to its original position, pushing air out of the lungs.
Besides the diaphragm, other muscles such as the intercostal muscles also assist in the breathing process. However, the diaphragm remains the most significant muscle involved, as it is the main driver of the breathing mechanism.