Upper Extremity Muscles and Actions

sternocleidomastoid

• Ipsilateral sidebending of head with rotation to opposite

• Bilateral neck flexion.

• Posterior fibers bilateral extension at O-A (Atlanto-Occipital) joint.

levator scapulae

• elevates scapula

• downward rotation of scapula

upper trapezius

• upwardly rotates with lower trapezius

• elevate working alone

• retract scapula

middle trapezius

retract scapula

lower trapezius

• upwardly rotate with upper trapezius

• depress working alone

• retract scapula

serratus anterior

• protract scapula and holds it against thoracic wall

• upward rotation of scapula

pectoralis major

• adduction and IR humerus

• clavicular head alone: flexes humerus

• sternocostal head (SC) alone: extension of humerus from overhead position

• horizontal adduction at g/h joint

pectoralis minor

• stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall

• depress tip of shoulder

anterior deltoid

abduction, flexion, IR of humerus

middle deltoid

abduction of humerus

posterior deltoid

extension, ER, abduction of humerus

supraspinatus

• initiates and assists deltoid in abduction of humerus

• holds head of glenoid cavity (rotator cuff)

subclavius

depresses the clavicle and anchors it

infraspinatus

• ER of humerus

• hold humeral head in glenoid (rotator cuff)

subscapularis

• IR of humerus

• hold head of humerus in place (rotator cuff)

teres major

extension, adduction, IR of humerus

rhomboids major and minor

• retract scapula

• elevate scapula

• downward rotation of scapula

• fix scapula against thoracic wall

latissimus dorsi

• extension, adduction, IR of humerus

• reverse action: elevates pelvis with arms fixed

• assists with forceful respiration

coracobrachialis

• flexion with adduction of humerus

• resists humeral dislocation

biceps brachii

• long-weak shoulder flexion

• weak abduction if humerus ER

• Both heads: elbow flexion with forearm supination

brachialis

elbow flexion regardless of position

brachioradialis

elbow flexion (midpronation most effective)

triceps

• all heads: elbow extension

• long head: resists dislocation of humerus

anconeus

assists in elbow extension

pronator teres

• pronates forearm

• flexes elbow

pronator quadratus

pronates forearm

supinator

supinates forearm

• extensor carpi radialis longus

• extensor carpi radial brevis

• extensor carpi ularis

extension and abduction of hand at wrist joint

extensor digitorum

• extension of medial 4 digits at MCP (metacarpophalangeal) joint

• assists with IP (interphalangeal) joint extension

• extension of hand at wrist joint

extensor digiti minimi

• extension of 5th digit at MCP (metacarpophalangeal)

• Extension at IP (interphalangeal) joints

extensor carpi ulnaris

extension and adduction of hand at wrist