Antebrachium Part 4: Extrinsic Muscles

extrinsic muscles of hand innervation

posterior interosseous N (branch of the radial N)

extensor digitorum origin

lateral epicondyle of humerus

extensor digitorum insertion

dorsal tendons insert on the bases of middle and distal phalanges 2-5

extensor digitorum action

- extension of digits 2-5

- extension of wrist

extensor indicis origin

distal aspect of ulnar shaft

extensor indicis insertion

tendons to extensor hood of 2nd digit

extensor indicis action

extension of digit 2

extensor digiti minimi origin

lateral epicondyle (of humerus)

extensor digiti minimi insertion

tendons insert on extensor hood of 5th digit

extensor digiti minimi action

extension of digit 5

flexor digitorum superficialis origin

- medial epicondyle (of humerus)

- radius

- coronoid process of ulna

flexor digitorum superficialis insertion

4 tendons insert on palmar surfaces of middle phalanges 2-5

flexor digitorum superficialis innervation

median N

flexor digitorum superficialis action

- flexion of proximal interphalangeal joints 2-5

- flexion of metacarpophalangeal joints

- flexion of wrist

flexor digitorum profundus origin

- anterior and medial surfaces of ulna

- anterior-medial half of interosseous membrane

flexor digitorum profundus insertion

4 tendons insert to palmar surface of distal phalanges 2-5

flexor digitorum profundus action

- flexion of distal interphalangeal joints 2-5

- flexion of metacarpophalangeal joints

- flexion of wrist

flexor digitorum profundus innervation

- (lateral) median N

- (medial) ulnar N

extensor pollicis longus origin

- shaft of ulna

- interosseous membrane

extensor pollicis longus insertion

dorsal surface of base of distal phalanx of thumb

extensor pollicis longus action

- extension of interphalangeal joint of thumb

- extension of metacarpophalangeal joint of thumb

- extension of carpometacarpal joint of thumb

extensor pollicis brevis origin

- posterior surface of radius

- radial half of interosseous membrane

extensor pollicis brevis insertion

dorsal surface of base of proximal phalanx 1

extensor pollicis brevis action

- extension of metacarpophalangeal joint of thumb

- extension of carpometacarpal joint

flexor pollicis longus origin

- anterior surface of radius

- radial half of interosseous membrane

flexor pollicis longus insertoin

palmar surface of base of distal phalanx 1

flexor pollicis longus action

- flexion of interphalangeal joint 1

- flexion of metacarpophalangeal joint 1

flexor pollicis longus innervation

anterior interosseus N (branch of median N)

abductor pollicis longus origin

- posterior surface of radius and ulna

- interosseous membrane

abductor pollicis longus insertion

lateral aspect of base of metacarpal 1

abductor pollicis longus action

- abducts carpometacarpal joint

- accessory extension of thumb

Lateral border of anatomical snuffbox

abductor pollicis longus and extensor pollicis brevis

medial border of anatomical snuffbox

extensor pollicis longus

Structure running through anatomical snuffbox

radial A