Which muscle primarily assists in shoulder abduction and stabilization?

The muscle that primarily assists in shoulder abduction and stabilization is the supraspinatus. This muscle is one of the four rotator cuff muscles and plays a crucial role in the initial phase of shoulder abduction. Specifically, it is responsible for lifting the arm away from the body, particularly in the first 15 degrees of motion.

In addition to its role in abduction, the supraspinatus contributes to the stabilization of the glenohumeral joint (the shoulder joint) by maintaining proper positioning of the humeral head within the shallow glenoid cavity of the scapula during arm movements. This stabilization is vital for the shoulder's function, particularly during dynamic activities that involve raising the arm.

While other muscles like the deltoid also play an important role in shoulder abduction, the supraspinatus is the key initiator and stabilizer in this specific action.