Anatomy Back and Limbs Muscle Actions

Trapezius

Elevate shoulder, depress shoulder, retract scapula medially

Latissimus dorsi

Extend and adduct humerus

Levator scapulae

Elevate scapula

Rhomboids

Depress glenoid fossa, retract scapula

Pectoralis major

Adduct humerus, medially rotate humerus at shoulder, protract scapula

Pectoralis minor

Hold scapula against thoracic wall

Subclavius

Anchor clavicle to first rib

Serratus anterior

Protract scapula

Deltoid

Abduct humerus, medially and laterally rotate humerus at shoulder

Teres major

Adduct humerus

Supraspinatus

Hold humeral head in glenoid fossa, laterally rotate humerus

Infraspinatus

Hold humeral head in glenoid fossa, laterally rotate humerus

Teres minor

Hold humeral head in glenoid fossa, laterally rotate humerus

Subscapularis

Hold humeral head in glenoid fossa, medially rotate humerus

Coracobrachialis

Adduct humerus, flex arm

Biceps brachii

Supinate forearm, flex supine forearm, help hold humeral head in glenoid fossa

Brachialis

Flex forearm in all positions

Triceps brachii

Extend forearm

Pronator teres

Pronate forearm, help flex forearm at elbow

Palmaris longus

Tense palmar aponeurosis

Flexor carpi radialis

Flex hand at wrist, abduct hand

Flexor carpi ulnaris

Flex hand at wrist, adduct hand

Flexor digitorum superficialis

Flex phalanges of digital fingers (not thumb)

Flexor digitorum profundus

Flex phalanges of digital fingers

Flexor pollicis longus

Flex pollex (thumb)

Pronator quadratus

Pronate forearm

Extensor carpi ulnaris

Extend and adduct hand at wrist

Extensor digitorum

Extend phalanges of digital fingers

Extensor digiti minimi

Extend phalanges of pinky

Supinator

Supinate forearm

Extensor pollicis longus

Extend phalanges of pollex (thumb)

Extensor pollicis brevis

Extend phalanges of pollex (thumb)

Abductor pollicis longus

Abduct phalanges of pollex (thumb)

Extensor indicis

Extend phalanges of index finger

Brachioradialis

Help flex forearm at elbow

Extensor carpi radialis longus

Extend and abduct hand at wrist

Extensor carpi radialis brevis

Extend and abduct hand at wrist

Lumbricals of the hand

Flex metacarpophalangeal joints, extend joints between proximal, middle, and distal phalanges; even out the speed at which fingers are flexed

Interossei of the hand

Abduct and adduct the middle three digits; adduct pinky

Quadriceps femoris

Extend leg at knee joint

Sartorius

Flex, abduct, and laterally rotate thigh at hip joint

Rectus femoris

Flex thigh at hip joint

Psoas

Flex thigh at hip joint, raise trunk when lying supine, posture muscle

Iliacus

Flex thigh at hip joint, raise trunk when lying supine

Pectineus

Adduct thigh at hip joint, weakly flex thigh at hip joint

Adductor brevis

Adduct thigh at hip joint

Adductor longus

Adduct thigh at hip joint, weakly flex thigh at hip joint

Gracilis

Adduct thigh at hip joint

Adductor magnus

Adduct thigh at hip joint, extend thigh at hip (hamstring portion)

Obturator externus

Laterally rotate thigh at hip joint

Semitendinosus

Extend thigh at hip, flex leg at knee, extend trunk at hip when thigh and leg are flexed

Semimembranosus

Extend thigh at hip, flex leg at knee, extend trunk at hip when thigh and leg are flexed

Biceps femoris

Extend thigh at hip, flex leg at knee

Gluteus maximus

Extend thigh at hip

Gluteus medius

Abduct and medially rotate thigh at hip

Gluteus minimus

Abduct and medially rotate thigh at hip

Piriformis

Laterally rotate thigh at hip, steady head of femur in hip joint

Superior gemellus

Laterally rotate thigh at hip, steady head of femur in hip joint

Obturator internus

Laterally rotate thigh at hip, steady head of femur in hip joint

Inferior gemellus

Laterally rotate thigh at hip, steady head of femur in hip joint

Quadratus femoris

Laterally rotate thigh at hip, steady head of femur in hip joint

Tensor of fascia lata

Abduct and medially rotate thigh at hip, steady head of femur in hip joint

Tibialis anterior

Dorsiflex foot, invert foot

Extensor digitorum longus

Dorsiflex foot, extend lateral four toes

Extensor hallucis longus

Dorsiflex foot, extend great toe

Fibularis longus

Evert foot

Fibularis brevis

Evert foot

Gastrocnemius

Flex leg, plantarflex foot

Soleus

Plantarflex foot

Plantaris

Proprioceptor; senses spatial position of foot

Popliteus

Unlocks fully extended knee

Flexor digitorum longus

Flex lateral four digits of foot

Flexor hallucis longus

Flex great toe

Tibialis posterior

Invert and plantarflex foot

Extensor hallucis brevis

Extend great toe

Extensor digitorum brevis

Extend lateral four toes

Abductor hallucis

Abduct great toe from midline of foot

Abductor digiti minimi

Abduct 5th toe from midline of foot

Adductor hallucis

Adduct great toe toward midline of foot

Flexor hallucis brevis

Flex great toe

Flexor digitorum brevis

Flex lateral four toes

Quadratus plantae

Straighten out tendon of flexor digitorum longus

Lumbricals of the foot

Even out flexion of toes

Plantar interossei

Adduct toes (PAD)

Dorsal interossei

Abduct toes (DAB)