The answer here is SUBSCAPULARIS; MEDIAL ROTATION
Rotator cuff muscles is composed of four distinct muscles and their tendons which give strength and stability to the shoulder especially during movement. They are referred to as the SITS muscle (Suprapinatus, Infraspinatus, Teres Minor and Subscapularis). All of the SITS muscles emerge from the scapula and connects to the head of the humerous forming a cuff at the glenohumeral joint. Supraspinatus helps the deltoid to abduct the arm, infraspinatus and teres minor both rotates the arm laterally and the subscapularis rotates the arm medially.
