The supraspinatus is a relatively small muscle of the upper back that runs from the supraspinatus fossa superior portion of the scapula (shoulder blade) to the greater tubercle of the humerus. It is one of the four rotator cuff muscles and therefore helps to stabilize the glenohumeral joint, it also abducts the arm at the shoulder. The spine of the scapula separates the supraspinatus muscle from the infraspinatus muscle, which originates below the spine.
The supraspinatus muscle performs abduction of the arm, and pulls the head of the humerus medially towards the glenoid cavity. It independently prevents the head of the humerus to slip inferiorly. Supraspinatus works in cooperation with the deltoid muscle to perform abduction, including when the arm is in adducted position. Beyond 15 degrees the deltoid muscle becomes increasingly more effective at abducting the arm and becomes the main propagator of this action.
Trigger points in the Supraspinatus are most frequently caused by activities that require loading of the arm, especially when the arm is hanging down to the side.
There are 3 trigger point in the Suprapinatus muscle all refure pain to the Deltoid muscle and down the arm.