UE Muscles - Posterior Forearm

extensor carpi radialis longus action

extend & abduct hand at wrist joint, active during fist clenching

extensor carpi radialis longus PA

lateral supra-epicondylar ridge of humerus

extensor carpi radialis longus DA

dorsal aspect of base of 2nd metacarpal

extensor carpi radialis longus innervation

radial nerve C6, C7

extensor carpi radialis brevis action

extend & abduct hand at wrist joint, active during fist clenching

extensor carpi radialis brevis PA

lateral epicondyle of humerus

extensor carpi radialis brevis DA

dorsal aspect of base of 3rd metacarpal

extensor carpi radialis brevis innervation

deep branch of radial nerve C7, C8

extensor digitorum action

extends medial 4 digits primarily at metacarpophalangeal joints, secondarily at interphalangeal joints

extensor digitorum PA

lateral epicondyle of humerus

extensor digitorum DA

extensor expansions of medial 4 digits

extensor digitorum innervation

deep branch of radial nerve C7, C8

extensor digiti minimi action

extends 5th digit primarily at metacarpophalangeal joint, secondarily at interphalangeal joint

extensor digiti minimi PA

lateral epicondyle of humerus

extensor digiti minimi DA

extensor expansion of 5th digit

extensor digiti minimi innervation

deep branch of radial nerve C7, C8

extensor carpi ulnaris action

extends & adducts hand at wrist joint, active during fist clenching

extensor carpi ulnaris PA

lateral epicondyle of humerus, posterior border of ulna via shared aponeurosis

extensor carpi ulnaris DA

dorsal aspect of base of 5th metacarpal

extensor carpi ulnaris innervation

deep branch of radial nerve C7, C8

supinator action

supinates forearm, rotates radius to turn palm anteriorly or superiorly if elbow is flexed

supinator PA

lateral epicondyle of humerus, radial collateral & anular ligaments, supinator fossa, crest of ulna

supinator DA

lateral, posterior, & anterior surfaces of proximal 1/3 of radius

supinator innervation

deep branch of radial nerve C7, C8

abductor pollicis longus action

abducts & extends thumb at carpometacarpal joint

abductor pollicis longus PA

posterior surface of proximal halves of ulna, radius, & interosseous membrane

abductor pollicis longus DA

base of 1st metacarpal

abductor pollicis longus innervation

posterior interosseous nerve C7, C8 & continuation of deep branch of radial nerve

extensor pollicis longus action

extends distal phalanx of thumb at interphalangeal joint, extends metacarpophalangeal & carpometacarpal joints

extensor pollicis longus PA

posterior surface of middle 1/3 of ulna & interosseous membrane

extensor pollicis longus DA

dorsal aspect of base of distal phalanx of thumb

extensor pollicis longus innervation

posterior interosseous nerve C7, C8 & continuation of deep branch of radial nerve

extensor pollicis brevis action

extends proximal phalanx of thumb at metacarpophalangeal joint, extends carpometacarpal joint

extensor pollicis brevis PA

posterior surface of distal 1/3 of radius & interosseous membrane

extensor pollicis brevis DA

dorsal aspect of base of proximal phalanx of thumb

extensor pollicis brevis innervation

posterior interosseous nerve C7, C8 & continuation of deep branch of radial nerve

extensor indicis action

extends 2nd digit enabling its independent extension, helps extend hand at wrist

extensor indicis PA

posterior surface of distal 1/3 of ulna & interosseous membrane

extensor indicis DA

extensor expansion of 2nd digit

extensor indicis innervation

posterior interosseous nerve C7, C8 & continuation of deep branch of radial nerve