What are the primary actions of the supraspinatus muscle?

The supraspinatus muscle plays a crucial role in shoulder movement and stability. Its primary actions include shoulder abduction, which is the movement of the arm away from the body, and stabilization of the humeral head within the glenoid cavity of the scapula. This stabilization is particularly important during arm movements, as it helps to keep the head of the humerus properly aligned within the shoulder joint, minimizing the risk of dislocation and ensuring smooth movement.

The abduction function of the supraspinatus is particularly prominent during the initial phases of abduction, where it works synergistically with the deltoid muscle to lift the arm. This makes it essential for various activities that require reaching or lifting the arm above shoulder level.

Furthermore, the muscle's location—sitting above the scapula—allows it to exert a stabilizing force on the shoulder joint, protecting it from injury during dynamic movements. This combination of actions—abduction and stabilization—highlights the supraspinatus's integral role in shoulder function and overall upper limb mobility.