Relacionar Columnas Muscle Actions Part OneVersión en línea muscles por Dr. David Myers 1 flexor carpi radialis and ulnaris 2 latissimus dorsi 3 deltoid 4 trapezius 5 levator scapulae 6 sternocleidomastoid 7 biceps brachii 8 pectoralis major 9 triceps brachii 10 rectus abdominis extends and laterally flexes the neck. adducts and medially rotates humerus, extends the shoulder joint extends elbow rotates head left and right. bilaterally draws head forward and down. flexes wrist anteriorly ant. fibers flex and medially rotate arm, lat. fibers abduct the arm, post. fibers extend and laterally rotate the arm elevates scapula if cervical vertebrae are fixed., flexes neck laterally when scapula is fixed. elbow flexion, forearm supination. flexes waist and compresses abdominal viscera flexes, adducts, and medially rotates humerus