Assess students' ability to recall and identify the four rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis), state each muscle's primary motor innervation (e.g., suprascapular, axillary, upper/lower subscapular nerves), and describe each muscle's principal action(s) at the glenohumeral joint (e.g., initiation of abduction, external rotation, internal rotation, stabilization). Scope: names, innervation source, and main action per muscle.