Shoulder Muscles contributing to the same function Contents FLEXION Anterior Deltoideus Pectoralis Major Coracobrachialis Biceps Brachii EXTENSION Posterior Deltoideus Latissimus Dorsi Teres Major Triceps Brachii (secondary function) Pectoralis Major (secondary function) ABDUCTION Deltoideus Supraspinatus Biceps Brachii (secondary function) Pectoralis Major (secondary function) ADDUCTION Pectoralis Major Latissimus Dorsi Teres Major Coracobrachialis Biceps Brachii (secondary function) Triceps Brachii (secondary function) Teres Minor (secondary function) LATERAL ROTATION Posterior Deltoideus Infraspinatus Teres Minor MEDIAL ROTATION Anterior Deltoideus Pectoralis Major Latissimus Dorsi Teres Major Subscapularis