The infraspinatus muscle is a muscle of the shoulder that connects the scapula (shoulder blade) to the humerus. It is one of the rotator cuff muscles responsible for laterally rotating the arm and stabilizing the shoulder.
The infraspinatus works in conjunction with the teres minor muscle, supraspinatus muscle, and subscapularis muscle, and is responsible for the lateral rotation of the arm and stabilization of the shoulder joint. It is the largest muscles of the group and is the one most cited in reference to rotator cuff injury and tearing. The infraspinatus is a fibrous muscle which is formed on each end by a tendon which attaches it to the skeleton.
The infraspinatus muscle is innervated by the suprascapular nerve.