Rotator cuff tears are tears of one or more of the four tendons of the rotator cuff muscles. A rotator cuff injury can include any type of irritation or damage to the rotator cuff muscles or tendons. Rotator cuff tears are among the most common conditions affecting the shoulder. The tendons of the rotator cuff, not the muscles, are most commonly torn. Of the four tendons, the supraspinatus is most frequently torn as it passes below the acromion; the tear usually occurs at its point of insertion onto the humeral head at the greater tubercule .