<P> The supraspinatus tendon is inserted into the superior facet of the greater tubercle of the humerus . The distal attachments of the three rotator cuff muscles that insert into the greater tubercle of the humerus can be abbreviated as SIT when viewed from superior to inferior (for supraspinatus, infraspinatus, and teres minor), or SITS when the subscapularis muscle, which attaches to the lesser tubercle of the humerus, is included . </P> <P> The suprascapular nerve (C5) innervates the supraspinatus muscle as well as the infraspinatus muscle . It comes from the upper trunk of the brachial plexus . This nerve can be damaged along its course in fractures of the overlying clavicle, which can reduce the person's ability to initiate the abduction . </P> <P> 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 . The 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 . </P> <P> Antero - posterior projectional radiography of the shoulder may demonstrate a high - riding humeral head, with an acromiohumeral distance of less than 7 mm . </P>

What is the function of the supraspinatus muscle
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