Supraspinatus

Anatomy

Origin:
Medial two-thirds of the supraspinous fossa of scapula.

Insertion:
Superior facet of greater tubercle of humerus.

Key Relations:
-The muscle forms a tendon that passes under the acromion and above the shoulder joint.
-One of the four muscles of the rotator cuff muscle group.

Functions

-Initiates abduction of the arm to 15° at glenohumeral joint.
– Contributes to the stability of the shoulder joint with the other rotator cuff muscles.
e.g as in holding your shopping bags away from your body..

Supply

Nerve Supply:
Suprascapular nerve (C5, C6).

Blood Supply:
-Suprascapular artery
-Dorsal scapular artery.

Clinical

The suprascapular nerve can be damaged along its course (for example in clavicular fractures) which can reduce the patient’s ability to initiate abduction of the arm. If the supraspinatus muscle is paralyzed, abduction may be initiated by leaning to the affected side. The deltoid muscle abducts the arm after 15°.

The tendon of supraspinatus is separated from the coraco-acromial ligament, acromion and deltoid by the large subacromial bursa. This tendon is most commonly ruptured component of the musculotendinous cuff around the shoulder joint.

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