What is the primary action of the subclavius muscle?

The primary action of the subclavius muscle is to stabilize the clavicle by moving it medially. This stabilization is crucial because the subclavius functions to protect the underlying structures, such as the brachial plexus and subclavian vessels, which run beneath it. By anchoring the clavicle to the first rib, the subclavius helps maintain proper positioning of the clavicle during movements of the arm and shoulder, contributing to the overall stability of the shoulder girdle.

The muscle also plays a role in assisting with movements that may require downward rotation of the scapula to help maintain proper alignment during upper extremity activities. However, its primary function remains centered on clavicular stabilization rather than facilitating movement in other shoulder actions like flexion or retraction.