 These muscles are responsible for several actions of the glenohumeral joint.The third group, which is mainly responsible for stabilization and rotation of the scapula, consists of the trapezius, serratus anterior, levator scapulae, and rhomboid muscles and attach to the medial, superior, and inferior borders of the scapula.Each of these muscles has their own role in shoulder function and must be in balance with each other in order to avoid shoulder pathology.