Muscles of the Forearm & Hand(Bio 107: Anatomy/Physiology) p.181-210

Flexor Carpi Ulnaris

Origin(proximal attachment) Humeral head- common tendon from the medial epicondyle of humerus Ulnar head- olecranon process & proximal two thirds of the posterior border of the ulna Insertion(distal attachment): pisiform bone, hook of the hamate, and the base of the fifth metacarpal bone Action: flexes & adducts the wrist Synergists: flexor carpi ulnaris and palmaris Antagonists: extensor carpi radialis longus and brevis, extensor ulnaris

Flexor Digitorum Superficialis

Origin(proximal attachment) Humeral head- medial epicondyle of the humerus through the common tendon and the medial margin of the coronoid process of the ulna Radial head- anterior surface of the shaft of the radius Insertion(distal attachment): 4 tendons divide into 2 slips each; the slips insert into the sides of the middle phalanges of the 4 fingers Action: flexes the wrist & the middle phalanges of fingers 2-5 Synergists: flexor digitorum Antagonists: extensor digitorum

Palmar Interossei

Origin(proximal attachment): First- medial side of base of 1st metacarpal bone Second, Third, Fourth- anterior surfaces of the 2nd, 4th, & 5th metacarpal bones Insertion(distal attachment): First- medial side of base of proximal phalanx of thumb Second- medial side of base of proximal phalanx of index fingers Third & Fourth- lateral side of proximal phalanges of ring finger & 5th finger Action: adducts finger toward center of 3rd finger @ metacarpophalangeal joints & assists in flexion of fingers at the same joints Synergists: flexors digitorum superficialis, profundus, flexor digiti minimi Antagonists: dorsal interossei, abductor digiti minimi, lumbricales

Pronator Teres

Origin(proximal attachment): Humeral head- just above the medial epicondyle of the humerus Ulnar head- medial side of the coronoid process of the ulna Insertion(distal attachment): middle of lateral surface of radius Action: pronates the forearm and assists in flexing the elbow join Synergists: pronator quadratus Antagonist: supinator

Adductor Pollicis

Origin(proximal attachment): Oblique head- anterior surfaces of 2nd & 3rd metacarpals, capitate & trapezoid bones Transverse head- anterior surface of 3rd metacarpal bone Insertion(distal attachment): medial side of base of proximal phalanx of thumb Action: adducts & flexes thumb Synergists: flexor pollicis brevis, flexor pollicis longus, opponens pollicis Antagonists: extensor pollicis brevis, extensor pollicis longus, abductor pollicis longus, abductor pollicis brevis

Dorsal Interossei

Origin(proximal attachment): adjacent sides of every 2 metacarpal bones Insertion(distal attachment): radial side of the proximal phalanx of the 2nd digit, radial, & ulnar side of the 3rd digit, & ulnar side of the 4th digit Action: abducts the index,middle, & ring fingers from the midline of the hand Synergists: abductor digiti minimi, extensor digitorum, extensor digiti minimi, lumbricales Antagonists: palmar interossei, flexors digitorum superficialis, profundus

Opponens Digiti Minimi

Origin(proximal attachment): anterior surface of flexor retinaculum & hook of hamate Insertion(distal attachment): whole length of the medial border to the 5th metacarpal bone Action: rotates 5th metacarpal bone into opposition with thumb, draws it forward, & assists in flexing carpometacarpal joint of 5th finger Synergists: flexor digiti minimi brevis, abductor digiti minimi Antagonists: dorsal interossei

Extensor Digitorum

Origin(proximal attachment): common extensor tendon from the lateral epicondyle of humerus Insertion(distal attachment): by 4 tendons to the lateral & dorsal surfaces of all the phalanges of digits 2-5 Action: extends the fingers & the wrists Synergists: extensor indicis, extensor digiti minimi, lumbricales Antagonists: flexor digitorum superficialis, flexor digitorum profundus

Extensor Carpi Ulnaris

Origin(proximal attachment): common tendon from the lateral epicondyle of humerus & posterior border of ulna Insertion(distal attachment): dorsal surface of base of 5th metacarpal bone Action: extends the wrist & assists in adduction of hand Synergists: extensor carpi radialis longus, extensor carpi radialis brevis Antagonists: flexor carpi radialis, flexor carpi ulnaris, palmaris longus

Extensor Digiti Minimi

Origin(proximal attachment): common tendon from the lateral epicondyle of the humerus Insertion(distal attachment): dorsal surface of base of the distal phalanx of the 5th digit Action: extends the 5th digit Synergists: extensor digitorum Antagonists: flexor digitorum superficialis, flexor digitorum profundus, flexor digiti minimi

Extensor Pollicis Brevis

Origin(proximal attachment): distal one-third of dorsal surface of radius & adjacent part of interosseous membrane Insertion(distal attachment): base of proximal phalanx of the thumb Action: extends thumb & abducts hand Synergists: abductor pollicis longus, extensor pollicis longus Antagonists: adductor pollicis, flexor pollicis longus

Flexor Digiti Minimi Brevis

Origin(proximal attachment): flexor retinaculum & hook of the hamate bone Insertion(distal attachment): medial side of base of proximal phalanx of the 5th digit Action: flexes 5th finger at metacarpophalangeal joint Synergists: flexor digitorum superficialis, flexor digitorum profundus, opponens digiti minimi Antagonists: extensor digitorum

Flexor Pollicis Brevis

Origin(proximal attachment): flexor retinaculum & trapezium bone Insertion(distal attachment): radial side of the base of the proximal phalanx of the thumb Action: flexes the proximal phalanx of the thumb Synergists: flexor pollicis longus, adductor pollicis Antagonists: extensor pollicis longus, extensor pollicis brevis, abductor pollicis

Abductor Pollicis Brevis

Origin(proximal attachment): flexor retinaculum, tubercle of the scaphoid bone Insertion(distal attachment): radial side of the base of the proximal phalanx of the thumb Action: abducts & assists in opposition of the thumb Synergists: abductor pollicis longus, extensor pollicis brevis Antagonists: flexor pollicis longus, adductor pollicis, opponens pollicis

Extensor Pollicis Longus

Origin(proximal attachment): interosseous membrane & middle one third of the posterior surface of the ulna Insertion(distal attachment): dorsal surface of the base of the distal phalanx of the 1st digit Action: extends the interphalangeal joints & assists in extension of the metacarpophalangeal joints in the thumb; also assists in abduction & extension of the wrist & the lateral rotation of the thumb Synergists: extensor pollicis brevis Antagonists: flexor pollicis longus

Extensor Indicis

Origin(proximal attachment): interosseous membrane & posterior surface of the ulna Insertion(distal attachment): into extensor expansion on dorsal surface of proximal phalanx of the index finger Action: extends the index finger at metacarpal phalanx joint Synergists: extensor digitorum Antagonists: flexor digitorum superficialis, flexor digitorum profundus

Supinator

Origin(proximal attachment): lateral epicondyle of humerus, annular and radial collateral ligaments, and supinator crest of ulna Insertion(distal attachment): lateral surface of the upper one third of the body of the radius Action: supinates the forearm Synergists: biceps brachii, accessory supinator Antagonists: pronator quadratus, pronator teres

Extensor Carpi Radialis Brevis

Origin(proximal attachment): lateral epicondyle of the humerus & the radial collateral ligament Insertion(distal attachment): dorsal surface of the base of the 3rd metacarpal bone Action: extends the wrist & assists in abduction of the hand Synergists: extensor carpi radialis longus, extensor carpi ulnaris Antagonists: flexor carpi radialis, flexor carpi ulnaris, palmaris longus

Extensor Carpi Radialis Longus

Origin(proximal attachment): lower third of lateral supracondylar ridge of humerus Insertion(distal attachment): dorsal surface of the base of the 2nd metacarpal bone Action: extends the wrist and abducts the hand Synergists: extensor carpi radialis brevis, extensor carpi ulnaris Antagonists: flexor carpi radialis, flexor carpi ulnaris, palmaris longus

Flexor Digitorum Profundus

Origin(proximal attachment): medial & anterior surfaces of the proximal three fourths of the ulna & the interosseus membrane Insertion(distal attachment): by 4 tendons into the anterior surface of the distal phalanxes of digits 2-5 Action: flexes the distal interphalangeal joints of digits 2-5 & assists in the adduction of the index, ring, and little fingers in flexion at the wrist Synergists: flexor digitorum superficialis Antagonist: extensor digitorum

Flexor Carpi Radialis

Origin(proximal attachment): medial epicondyle of the humerus Insertion(distal attachment): base of 2nd and 3rd metacarpal bones Action: flexes wrist and abducts hand Synergists: flexor carpi ulnaris, palmaris longus for flexion Antagonists: extensor carpi radialis longus and brevis, extensor ulnaris

Palmaris Longus

Origin(proximal attachment): medial epicondyle of the humerus through the common flexor tendon Insertion(distal attachment): front of flexor retinaculum and apex of the palmar aponeurosis Action: tenses the palmar fascia and flexes the wrist Synergists: flexor carpi radialis, flexor carpi ulnaris, flexor digitorum superficialis Antagonists: extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, extensor digitorum

Pronator Quadratus

Origin(proximal attachment): medial side of the anterior surface of the distal one-fourth of the ulna Insertion(distal attachment): lateral side of the distal one-fourth of the radius Action: pronation of the forearm Synergists: pronator teres Antagonists: supinator

Flexor Pollicis Longus

Origin(proximal attachment): middle of anterior shaft of the radius & interosseus membrane Insertion(distal attachment): planar surface of the base of the distal phalanx of the thumb Action: flexes the thumb; assists in abduction of wrist Synergist: flexor pollicis brevis, adductor policis Antagonists: extensor pollicis longus, extensor pollicis brevis, abductor pollicis longus

Abductor Digiti Minimi

Origin(proximal attachment): pisiform bone & the tendon of the flexor capri ulnaris Insertion(distal attachment): medial side of base of proximal phalanx of the 5th digit Action: abducts the 5th finger Synergists: flexor digiti minimi brevis, opponens digiti minimi Antagonists: palmar interossei

Abductor Pollicis Longus

Origin(proximal attachment): posterior surface of the body of the ulna distal to the origin of the supinator, the interosseous membrane, & the middle one third of the body of the radius Insertion(distal attachment): dorsal surface of the base of the first metacarpal bone Action: abducts & extends the 1st digit & abducts the wrist Synergists: extensor pollicis brevis, abductor pollicis brevis Antagonists: extensor pollicis longus, extensor pollicis brevis, adductor pollicis

Opponens Pollicis

Origin(proximal attachment): retinaculum(transverse carpal ligament) & trapezium bone Insertion(distal attachment): anterior surface on the radial side of the 1st metacarpal bone Action: rotates thumb into opposition with fingers, acts together with other muscles of the thenear eminence to oppose thumb to fingers Synergists: flexor pollicis longus and brevis, adductor pollicis Antagonists: extensors pollicis longus and brevis, abductors pollicis longus and brevis

Lumbricals

Origin(proximal attachment): tendons of flexor digitorum profundus in palm Insertion(distal attachment): lateral side of corresponding tendon of extensor digitorum on digits 2-5 Action: extends fingers at interphalangeal joints & weakly flex fingers at metacarpophalangeal joint Synergists: extensor digitorum, extensor indices, extensor digiti minimi Antagonists: flexors digitorum superficialis, profundus

Palmaris Brevis

Origin: palmar aponeurosis Insertion: skin of palm of hand Action: corrugates skin of palm