Which muscles assist in the breathing process between the chest and abdomen?

The diaphragm is a dome-shaped muscle located at the base of the thoracic cavity and is the primary muscle involved in the process of breathing. It separates the chest cavity from the abdominal cavity and plays a crucial role during inhalation and exhalation. When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity and allowing air to flow into the lungs. When the diaphragm relaxes, it moves back up, decreasing the thoracic cavity's volume and helping expel air from the lungs.

While intercostal muscles support the diaphragm by assisting with the expansion and contraction of the chest cavity, and abdominal muscles can aid in forced exhalation by pushing the diaphragm upwards, the diaphragm remains the most critical muscle for initiating the breathing process itself. Pectoral muscles primarily assist in arm movement rather than directly impacting respiration. Hence, identifying the diaphragm as the main muscle in this context highlights its essential role in facilitating breathing.