Muscles of Mastication Masseter elevation of mandible, protraction, retraction, and lateral and medial excursion Temporalis elevation, retraction, and lateral and medial excursion of the mandible Medial pterygoid elevation, protraction, and lateral and medial excursion of the mandible Lateral pterygoid depression, protraction, and lateral and medial excursion of the mandible Buccinator compresses cheek against teeth and gums, kissing muscle Muscles of Trunk External intercostals elevate ribs during respiration Internal intercostals depresses ribs during respiration Diaphragm principal muscle of respiration External oblique rotates trunk to opposite side Internal oblique rotates trunk to same side Transversus abdominis constricts abdominal contents Rectus abdominis flexion and lateral flexion of trunk Muscles of Pelvis Floor Levator ani compresses anal canal and reinforces external anal and urethral sphincters Coccygeus aids levator ani Superficial transverse perineus extends from ischial tuberosities to a strong median fibromuscular anchorage Ischiocavernosus maintains erection of penis or clitoris by forcing blood Bulbocavernosus expels remaining urine from urethra after bladder has emptied Muscles of Back & Neck Trapezius elevates and depresses apex of shoulder Latissimus dorsi adducts and medially rotates humerus Levator scapula elevates scapula, flexes neck laterally Rhomboids retract scapula and brace shoulder Splenius deep muscle group Erector spinae Transversospinalis Sternocleidomastoid draws head toward ipsilateral shoulder and rotates head to opposite side; flexes head Muscles of the Shoulder Pectoralis major flexes, adducts, and medially rotates humerus Pectoralis minor draws scapula laterally and forward around chest wall Subclavius stabalizes clavical Serratus anterior protracts scapula, prime mover in all forward-reaching and pushing actions Subscapularis prevents humerus from sliding upward as arm is abducted; rotates humerus medially Supraspinatus abducts arm and resists downward slippage of humeral head Infraspinatus prevents humerus from sliding upward, rotates humerus laterally Teres minor prevents humerus from sliding upward as arm is abducted, rotates humerus laterally Teres major extends and medially rotates humerus Deltoid anterior-flex and medially rotate arm; lateral- abduct arm;posterior-extend and laterally rotate arm Muscles of the Arm Biceps brachii flexion of elbow Coracobrachialis flexes and medially rotates arm Brachialis prime mover for flexion of elbow Triceps brachii extension of arm Muscles of the Forearm Pronator teres assists pronator quadratus in rapid or forceful action Flexor carpi radialis flexes wrist, radial deviation Palmaris longus anchors skin and fascia of palmar region Flexor carpi ulnaris flexes wrist, ulnar deviation Flexor digitorum superficilais flexes wrist, metacarpophalangeal, and interphalangeal joints Flexor pollicis longus flexes phalanges of thumb Flexor digitorum profundus flexes wrist, metacarpophalangeal, and interphalangeal joints; sole flexor of distal interphalangeal joints Pronator quadratus prime mover of forearm pronation Brachioradialis flexes elbow Extensor carpi radialis longus extends wrist; aids in radial deviation Anconeus extends elbow Extensor carpi radialis brevis extends wrist, aids in radial deviation Extensor digitorum extends wrist, metacarpophalangeal, and interphalangeal joints Extensor digiti minimi extends wrist and all joints of little finger Extensor carpi ulnaris extends and fixes wrist when fist is clenched or hand grips an object; aids in ulnar deviation Supinator supinates forearm Abductor pollicis longus abducts thumb, extends thumb Extensor pollicis brevis extends metacarpal and proximal phalanx of thumb Extensor pollicis longus extends distal phalanx I, adducts and laterally rotates thumb Extensor indicis extends wrist and index finger Muscles of Hand Abductor pollicis brevis abducts thumb in sagittal plane Oppens pollicis flexes metacarpal I to oppose thumb to fingertips Flexor pollicis brevis flexes metacarpophalangeal joint of thumb Adductor pollicis draws thumb toward palm as in gripping a tool Abductor digiti minimi abducts little finger Opponens digiti minimi flexes metacarpal V at carpometacarpal joint, deepends palm of hand Flexor digiti minimi flexes little finger Lumbricals extened interphalangeal joints, contribute ability to pinch between fleshy pulp of thumb and finger Palmar interossei adduct fingers, grip strength Dorsal interossei abduct fingers, grip strength Muscles of the Hip Gluteus maximus extends thigh at hip, abducts thigh, elevates trunk Gluteus medius abduct and medially rotate thigh Gluteus minimus abduct and medially rotate thigh Tensor fascia lata extends knee, laterally rotates tibia Piriformis laterally rotate extended thigh and abduct flexed thigh Obturator internus laterally rotate extended thigh and abduct flexed thigh Superior gemellus laterally rotates extended thigh; abducts flexed thigh Inferior gemellus laterally rotates extended thigh; abducts flexed thigh Quadratus femoris laterally rotates thigh Obturator externus laterally rotates thigh in climbing Muscles of the Thigh Rectus femoris extends knee, flexes thigh at hip Vastus lateralis extends knee, retains patella in groove Vastus intermedius extends knee Vastus medialis extends knee, retains patella in groove Sartorius aids in knee and hip flexion, abducts and laterally rotates thigh Iliopsoas iliacus and psoas major: flexion of hip Biceps femoris flexes knee, extends hip Semitendinosus flexes knee, medially rotates tibia or femur Semimembranosus flexes knee, medially rotates tibia or femur Gracilis flexes and medially rotates tibia at knee Pectineus flexes and adducts thigh Adductor longus adducts and medially rotates thigh; flexes thigh at hip Adductor brevis adducts thigh Adductor magnus adducts and medially rotates thigh; extends thigh at hip Muscles of the Leg Tibialis anterior dorsiflexes and inverts foot Extensor digitorum longus extends toes, dorsiflexes foot Fibulares (peroneus) tertius dorsiflexes and everts foot Extensor hallucis longus extends great toe, dorsiflexes foot Fibulares (peroneus) longus maintains concavity of sole during toe-off and tiptoeing, everts and plantar flexes foot Fibulares (peroneus) brevis maintains concavity of sole during toe-off and tiptoeing Gastrocnemius plantar flexes foot, knee Soleus plantar flexes foot Plantaris planter flexes and inverts foot, flexes leg at knee Popliteus rotates tibia medially or femur laterally, unlocks knee to allow flexion Tibialis posterior inverts foot Flexor digitorum longus flexes phalanges of digits II-V as foot is raised from ground Flexor hallucis longus flexes phalanges of digit I as foot is raised from ground