What is the name of the large muscle located at the bottom of the chest cavity that aids in breathing?

The diaphragm is the large muscle located at the base of the chest cavity that plays a critical role in the breathing process. When the diaphragm contracts, it flattens and moves downward, increasing the volume of the thoracic cavity. This negative pressure allows air to flow into the lungs, facilitating inhalation. When the diaphragm relaxes, it returns to its dome-shaped position, decreasing the thoracic cavity's volume and aiding in expelling air from the lungs during exhalation. This muscle is essential for efficient respiration, making it the primary driver of the breathing process.

In contrast, the intercostal muscles are located between the ribs and assist with expanding and contracting the chest during respiration but do not serve as the main muscle for the process. The abdominal muscles play a role in forceful exhalation rather than the inhalation process. Pectoral muscles are primarily involved in arm movement and do not directly contribute to respiration. Thus, the diaphragm stands out as the primary muscle responsible for breathing.