( Supraspinatus, Infraspinatus, Teres minor, Subscapularis)

Insertion: greater tubercle of humerus

Innervation: suprascapular nerve (C4, C6)

Function: initiation of abduction of arm to 15° at glenohumeral joint; stabilization of humeral head in glenoid cavity.

Origin: infraspinatous fossa of scapula

Insertion: greater tubercle of humerus

Innervation: suprascapular nerve (C5, C6)

Function: external rotation of arm at glenohumeral joint; stabilization of the humeral head in glenoid cavity.

Origin: lateral border of scapula

Insertion: greater tubercle of humerus

Innervation: axillary nerve (C5, C6)

Function: external rotation and adduction of arm at glenohumeral joint; stabilization of the humeral head in glenoid cavity.

Origin: medial two-third of the subscapular fossa

Insertion: lesser tubercle of the humerus

Innervation: upper and lower subscapular nerves (C5, C7)

Function: internal rotation of arm; stabilization of humeral head in glenoid cavity.