Shoulder tendinitis, tendinopathy, tendon pathology. Tendinitis (or tendinopathy) of the shoulder reflects the wear of the tendons over time and by excessive use. It is a pathology of the tendons that affects the rotator cuff. The rotator cuff unites 4 tendons, the supraspinatus, the infraspinatus, the subscapular, the small round. The tendon of the subscapularis muscle is not shown here because it is visible in an anterior view. Outside this drawing represents a posterior view with the arm raised which allows to show the long biceps. The long biceps tendon is also considered to be the rotator cuff tendon for its shoulder stabilizing action.