The supraspinatus (plural supraspinati) is a relatively small muscle of the upper back. Supraspinatus,Infraspinatus, Subscapularis and Teres Minor together This Four Muscle work as rotatory to the Humerus. so also known as Rotator Cuff . Supraspinatus ORIGIN: Supraspinatus originates from supraspinous fossa of the scapula. Supraspinatus INSERTION: Supraspinatus is inserted at the superior part of greater tubercle of the humerus. Supraspinatus ACTION: Supraspinatus stabilizes the shoulder joint. Supraspinatus helps prevent downward dislocation of the humerus. Supraspinatus NERVE SUPPLY: Supraspinatus is innervated by Suprascapular nerve.