Final answer:
The trapezius, rhomboid major, and rhomboid minor are the three muscles that move the scapula medially. They are part of the posterior thoracic muscles that position the pectoral girdle.
Step-by-step explanation:
Only three muscles of the group known as the muscles of the scapula move the scapula medially: the trapezius, rhomboid major, and rhomboid minor. These muscles are located on the posterior thorax and work to position the pectoral girdle. When the rhomboids contract, they move the scapula medially, which can pull the shoulder and upper limb posteriorly. The scapula itself is a flat, triangular bone that supports muscles crossing the shoulder joint, such as the deltoid, subscapularis, supraspinatus, infraspinatus, teres major, teres minor, and coracobrachialis.