What is the primary function of the diaphragm during inhalation?

The diaphragm plays a crucial role in the process of inhalation primarily by increasing the volume of the thoracic cavity. When the diaphragm contracts, it moves downward, creating a larger space in the thoracic cavity. This increase in volume leads to a decrease in pressure inside the thoracic cavity compared to the atmospheric pressure outside the body. As a result, air is drawn into the lungs to equalize the pressure difference, facilitating the process of inhalation.

This mechanism is essential for effective breathing, as the diaphragm's contraction not only allows for the expansion of the rib cage but also supports overall lung ventilation. Other functions, such as pushing air out of the lungs or stabilizing the chest wall, are secondary to this primary action during inhalation. The only correct function in this context is that the diaphragm increases thoracic cavity volume, directly enabling air inflow.