Supraspinatus muscle

Origin and insertion

Supraspinatus is the most superior of the four rotator cuff muscles. It is a small triangular-shaped muscle, located on the posterior aspect of the scapula. It originates from the medial aspect of the supraspinous fossa, a concave depression located above the spine of the scapula.

The muscle fibers converge onto a tendon that runs inferior to the acromion of the scapula. After passing over the glenohumeral joint it inserts onto the superior facet on the greater tubercle of humerus.

Relations

Supraspinatus lies deep to the trapezius muscle and superior to the spine of the scapula and infraspinatus muscle. The tendon of supraspinatus is separated from the coracoacromial ligament, the acromion and the deltoid muscle by the subacromial bursa.

Innervation

Supraspinatus is innervated by the suprascapular nerve, formed by the anterior rami of spinal nerves C5 and C6.

Blood supply 

Supraspinatus receives arterial supply from the suprascapular artery, a branch of the thyrocervical trunk of subclavian artery. The suprascapular artery passes through the suprascapular notch,  along with the suprascapular nerve to supply supraspinatus. 

Supraspinatus sometimes receives a collateral blood supply via the dorsal scapular artery. Venous drainage is conveyed by the same-named veins which accompany the arteries and drain into the subclavian vein.

Function

During movements of the glenohumeral joint, the supraspinatus muscle participates in the stabilization of the head of humerus in the joint. It also assists the deltoid muscle in abduction of the arm at the glenohumeral joint. 

Learn more about the supraspinatus and other muscles of the rotator cuff with the following quiz.