Posterior forearm-deep

• Supinator origin

  lateral epicondyle
• supinator insertion

  anterolateral surface of radius
• supinator action

  supinate forearm
• extensor indicis origin

  posteior ulna and interosseous membrane
• extensor indicis insertion

  posterior surface of proximal phalanx of digit 2
• extensor indicis action

  extend digit 2
• abductor pollicis longus origin

  posterior ulna, radius, interosseous membrane
• abductor pollicis longus insertion

  metacarpal 1 and trapezium
• abductor pollicis longus action

  abduct thumb and wrist
• extensor pollicis longus origin

  posterior/lateral ulna and interosseous membrane
• extensor pollicis longus insertion

  distal phalanx of thumb
• extensor pollicis longus action

  extend thumb and abduct at wrist
• extensor pollicis brevis origin

  posterior distal radius and interosseous membrane
• extensor pollicis brevis insertion

  proximal phalanx of thumb
• extensor pollicis brevis action

  extend thumb and abduct at wrist
• innervation of extensor pollicis brevis, longus, abductor pollicis longus, extensor indicis, supinator

  deep radial nerve