The supraspinatus is the most superior of the four rotator cuff muscles, lying in the supraspinous fossa above the scapular spine and travelling beneath the acromion and coracoacromial ligament to attach to the top of the humerus. It initiates arm abduction by depressing and stabilising the humeral head before the deltoid generates the main abduction force, and its tendon passes through the subacromial space, the narrowest passage in the shoulder, making it the most commonly impinged and torn of all rotator cuff tendons.
| Origin | Supraspinous fossa of the scapula |
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| Insertion | Superior facet of the greater tubercle of the humerus |
| Nerve Supply | Suprascapular nerve (C5, C6) |
| Blood Supply | Suprascapular artery |
| Actions | Initiates abduction of the arm (first 0–15°); Contributes to full abduction in conjunction with the deltoid; Stabilises the humeral head in the glenoid during arm movements, depresses the humeral head against superior translation |
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Its most critical functional role is not power generation but joint centration, keeping the humeral head seated centrally in the shallow glenoid while the larger muscles move the arm, preventing superior migration that would compress the subacromial structures.
Supraspinatus pathology is the most common cause of shoulder pain in adults over 40, ranging from impingement and tendinopathy to partial and full-thickness tears, and often presents as a painful arc of abduction between 60° and 120° where the tendon is compressed beneath the acromion. The empty can and full can tests are the standard clinical screens for supraspinatus integrity. Full-thickness tears lose the ability to actively compress the humeral head, causing superior migration and accelerated degeneration of adjacent structures.
The supraspinatus tendon is accessible just anterior to the acromion when the arm is slightly extended behind the body, rolling the shoulder backward brings the tendon out from under the acromion. Tenderness here with resisted arm abduction in the scapular plane confirms supraspinatus involvement.
Degenerative changes within the supraspinatus tendon producing a painful arc between 60° and 120° of abduction, worsening with overhead activities, and associated with reduced subacromial space, poor scapular kinematics, or both.
An incomplete tear through the tendon, more common on the articular surface than the bursal side, producing similar symptoms to tendinopathy but typically with greater pain on the Hawkins and Neer impingement tests and a positive empty can.
A complete rupture through the tendon causing loss of the supraspinatus force couple, significant strength loss in resisted abduction, and inability to maintain the humeral head depressed during arm elevation, confirmed by ultrasound or MRI.
