Wrist Extensors

Other Names

• Forearm (outer or back)
• Hand Extensors

Heads

1. Extensor Digitorum
2. Extensor Carpi Radialis Longus
3. Extensor Carpi Radialis Brevis
4. Extensor Carpi Ulnaris
5. Extensor Indicis
6. Extensor Digiti Minimi
7. Entensor Pollicis Longus
8. Extensor Pollicis Brevis

Movement

Wrist

• Extension [1, 2, 3, 4, 5, 6, 7]
• Abduction [2, 3, 7, 8]
• Adduction [4]

Fingers

• Extension
  • Index [1, 5]
  • Middle [1]
  • Ring [1]
  • Little [1, 6]
• Abduction
  • Index [1, 5]
  • Middle [1]
  • Ring [1]
  • Little [1, 6]

Thumb

• Extension [7, 8]

Elbow (very weak)

• Extension [1, 2, 3, 4]

Attachments

Origin

• Humerus (Lateral Distal)
  • Lateral Epicondyle [1, 2, 3, 4, 6]
• Ulna (Posterior Lateral) [5, 7]
• Radius (Medial Lower Middle) [8]

Insertion

• Fingers (Dorsal)
  • Four Fingers [1]
    • Second & Third Phalanges
  • Index [5]
    • Proximal Phalanx
    • Extensor Expansion
  • Little [6]
    • Proximal Phalanx
• Thumb (Dorsal)
  • Base of Distal Phalanx [7]
  • Base of Proximal Phalanx [8]
• Metacarpals (Dorsal)
  • Second [2]
  • Third [3]
  • Fifth [4]

Comments

The triarticulate [1] and biarticulate [2, 3, 4, 5, 6, 7, 8 ] wrist extensor muscles may independently enter passive insufficiency through the completion of one of 4 eccentric joint movements (opposite movements of the wrist, fingers, thumb, elbow) when an adjacent joint eccentric movement is sustained. The triarticulate and biarticulate wrist extensor muscles may independently enter active insufficiency through the completion of one of 4 concentric joint movements (movements of the wrist, fingers, thumb, elbow) when an adjacent joint concentric movement is sustained.