Muscle Actions of Upper and Lower Limbs

Latissimus dorsi

Extends, adducts, and medially rotates the arm; assists in respiration

Pectoralis major

Adducts and medially rotates humerus; flexes and extends humerus

Pectoralis minor

Stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall

Subclavius

Anchors and depresses clavicle

Serratus anterior

Protracts scapula and holds it against thoracic wall; rotates scapula upward

Deltoid

Flexes, abducts, extends, and rotates arm (anterior, middle, posterior fibers)

Supraspinatus

Initiates and assists deltoid in abduction; stabilizes shoulder

Infraspinatus

Laterally rotates and stabilizes arm

Teres minor

Laterally rotates and weakly adducts arm; stabilizes shoulder

Teres major

Adducts, extends, and medially rotates arm

Subscapularis

Medially rotates arm; stabilizes shoulder

Biceps brachii

Supinates and flexes forearm

Coracobrachialis

Helps flex and adduct arm

Brachialis

Flexes forearm in all positions

Triceps brachii

Extends forearm

Anconeus

Assists triceps in forearm extension

Pronator teres

Pronates and flexes forearm

Flexor carpi radialis

Flexes and abducts hand at wrist

Palmaris longus

Flexes hand and tenses palmar aponeurosis

Flexor carpi ulnaris

Flexes and adducts hand at wrist

Flexor digitorum superficialis

Flexes PIP and MCP joints of fingers and wrist

Flexor digitorum profundus

Flexes DIP, PIP, MCP joints and wrist

Flexor pollicis longus

Flexes thumb

Pronator quadratus

Pronates forearm

Brachioradialis

Weak flexion of forearm; maximal in midpronation

Extensor carpi radialis longus

Extends and abducts hand at wrist

Extensor carpi radialis brevis

Extends and abducts hand at wrist

Extensor digitorum

Extends fingers and hand at wrist

Extensor digiti minimi

Extends 5th digit

Extensor carpi ulnaris

Extends and adducts hand

Supinator

Supinates forearm

Extensor indicis

Extends 2nd digit; helps extend wrist

Abductor pollicis longus

Abducts thumb

Extensor pollicis longus

Extends thumb at all joints

Extensor pollicis brevis

Extends MCP and CMC joints of thumb

Abductor pollicis brevis

Abducts thumb

Flexor pollicis brevis

Flexes thumb

Opponens pollicis

Opposes thumb

Adductor pollicis

Adducts thumb

Abductor digiti minimi

Abducts 5th digit

Flexor digiti minimi brevis

Flexes 5th digit

Opponens digiti minimi

Opposes 5th digit

Lumbricals 1 and 2

Flex MCP joints; extend IP joints of fingers 2-5

Lumbricals 3 and 4

Flex MCP joints; extend IP joints of fingers 2-5

Dorsal interossei (1-4)

Abduct digits 2-4

Palmar interossei (1-3)

Adduct digits 2, 4, and 5

Gluteus medius

Extends and laterally rotates hip; assists in rising from sitting

Gluteus minimus

Abducts and medially rotates hip; stabilizes pelvis

Tensor fasciae latae

Abducts and medially rotates hip; tenses fascia lata

Piriformis

Laterally rotates and abducts hip

Obturator internus

Laterally rotates and abducts hip

Superior gemellus

Laterally rotates and abducts hip

Inferior gemellus

Laterally rotates and abducts hip

Quadratus femoris

Laterally rotates hip

Pectineus

Adducts, flexes, and laterally rotates hip

Psoas major

Flexes and stabilizes hip

Psoas minor

Weak flexor of trunk

Iliacus

Flexes and stabilizes hip

Sartorius

Flexes, abducts, laterally rotates hip; flexes knee

Rectus femoris

Extends knee; helps flex hip

Vastus lateralis

Extends knee

Vastus medialis

Extends knee

Vastus intermedius

Extends knee

Adductor longus

Adducts hip

Adductor brevis

Adducts and slightly flexes hip

Adductor magnus

Adducts hip; flexes and extends hip

Gracilis

Adducts hip; flexes and medially rotates knee

Obturator externus

Laterally rotates and stabilizes hip

Semitendinosus

Extends hip; flexes and medially rotates knee

Semimembranosus

Extends hip; flexes and medially rotates knee

Biceps femoris (long head)

Extends hip; flexes and medially rotates knee

Biceps femoris (short head)

Extends hip; flexes and laterally rotates knee

Tibialis anterior

Dorsiflexes ankle; inverts foot

Extensor digitorum longus

Extends toes; dorsiflexes ankle

Extensor hallucis longus

Extends great toe; dorsiflexes ankle

Fibularis tertius

Dorsiflexes ankle; everts foot

Fibularis longus

Everts foot; weak plantarflexor

Fibularis brevis

Everts foot; weak plantarflexor

Gastrocnemius

Plantarflexes ankle; flexes knee

Soleus

Plantarflexes ankle; stabilizes ankle

Plantaris

Assists in plantarflexion

Popliteus

Unlocks and flexes knee

Flexor hallucis longus

Flexes great toe; plantarflexes ankle

Flexor digitorum longus

Flexes lateral toes; plantarflexes ankle

Tibialis posterior

Plantarflexes and inverts foot; supports arch

Abductor hallucis

Abducts and flexes great toe

Flexor digitorum brevis

Flexes lateral four digits

Quadratus plantae

Assists in flexing toes

Lumbrical 1

Flexes proximal IP; extends distal IP of toes

Lumbricals 2-4

Flexes proximal IP; extends distal IP of toes

Flexor hallucis brevis

Flexes great toe

Adductor hallucis

Adducts great toe; maintains transverse arch

Plantar interossei (3)

Adduct and flex toes 3-5

Dorsal interossei (4)

Abduct and flex toes 2-4

Extensor digitorum brevis

Extends intermediate toes

Extensor hallucis brevis

Extends great toe