Medial rotation of the arm involves the movement of the humerus turning inward towards the midline of the body. This motion is produced by the coordinated action of several muscles. The subscapularis, one of the rotator cuff muscles, plays a primary role in this movement. It originates from the subscapular fossa on the anterior surface of the scapula and inserts onto the lesser tubercle of the humerus. Its position and fibre direction allow it to pull the humerus into medial rotation. The pector