Deep Posterior Forearm Muscles

Front 1

supinator

Back 1

1) action: supinates forearm
2) origin: lateral epicondlye of humerus
3) insertion: proximal third of radius
4) innervation: deep branch of radial nerve
5) blood supply: Recurrent interosseous artery

Front 2

abductor pollicis longus

Back 2

1) action: abducts and extends thumb
2) origin: posterior suface of proximal halves of ulna, radius, and interosseous membrane
3) insertion: base of 1st metacarpal
4) innervation: posterior interosseous nerve continuation of deep radial nerve
5) blood supply: Posterior interosseous artery

Front 3

extensor pollicis longus

Back 3

1) action: extends distal phalanx of thumb at interphalangeal joint; extends metacarpophalangeal and carpometacarpal joints
2) origin: posterior surface of middle third of ulna and interosseous membrane
3) insertion: dorsal aspect of base of distal phalanx of thumb
4) innervation: posterior interosseous nerve continuation of deep branch of radial nerve
5) blood supply: Posterior interosseous artery

Front 4

extensor pollicis brevis

Back 4

1) action: extends proximal phalanx of thumb at metacarpophalangeal joint; extends carpometacarpal joint
2) origin: posterior surface of dsital third of radius and interosseous membrane
3) insertion: dorsal aspect of base of proximal phalanx of thumb
4) innervation posterior interosseos nerve continuation of deep branch of radial nerve
5) blood supply: Posterior interosseous artery

Front 5

extensor indicis

Back 5

1) action: extends 2nd finger
2) origin: posterior surface of distal third of ulna and interosseous membrane
3) insertion: extensor expansion of 2nd finger
4) innervation: posterior interosseous continuation of deep branch of radial nerve
5) blood supply: Posterior interosseous artery