During respiration, inhalation is primarily carried out by which muscle?

Inhalation during respiration is primarily carried out by the diaphragm, which is a dome-shaped muscle located beneath the lungs. When the diaphragm contracts, it flattens and moves downward, increasing the thoracic cavity's volume and decreasing the pressure within it. This pressure change allows air to flow into the lungs from the atmosphere, facilitating inhalation.

While the other muscles listed do play roles in the respiratory process, they are not the primary initiators of inhalation. The external intercostals assist by elevating the rib cage and expanding the thoracic cavity, while the internal intercostals are more involved in forced exhalation. The scalenes also assist with inhalation by elevating the first two ribs but do so to a lesser extent. Overall, the diaphragm is the most significant muscle responsible for the initial phase of inhalation.