What is the primary function of the supraspinatus muscle?

The primary function of the supraspinatus muscle is to abduct the humerus. This muscle is one of the four rotator cuff muscles and is located at the top of the shoulder. Specifically, it is responsible for initiating the movement of abduction, which is the movement of the arm away from the body.

The role of the supraspinatus is particularly important in the early range of abduction, typically the first 15 to 30 degrees, after which the deltoid muscle takes over significantly in continuing the movement. This action is critical not only for various overhead activities but also for many functional movements that require raising the arm.

While other movements like adduction, extension, and medial rotation can involve other muscles, they do not capture the primary action of the supraspinatus as effectively as abduction does.