What is the primary muscle involved in breathing?

The diaphragm is the primary muscle involved in the process of breathing, specifically in inhalation. It is a dome-shaped muscle located at the base of the thoracic cavity, separating the thorax from the abdomen. During inhalation, the diaphragm contracts and moves downward, increasing the volume of the thoracic cavity. This drop in pressure allows air to flow into the lungs. The diaphragm's unique position and structure make it the most essential muscle for respiration, as it contributes significantly to the mechanics of breathing.

While the intercostal muscles play a role by assisting with the expansion and contraction of the rib cage during breathing, the diaphragm is primarily responsible for the majority of the air movement in a typical breathing cycle. Other muscles, such as the rectus abdominis and pectoralis major, may assist in forceful breathing or specific activities but are not the primary muscles engaged during the normal inhalation process.