Extensor Digitorum

Seattle Figure Studio
Sep 18, 2025
Reviewed

Summary

Henry Vandyke Carter, Public domain, via Wikimedia Commons

Origins

Insertions

  • Extensor expansions of digits two through five

Actions

  • Extends digits two through five
  • Assists wrist extension

The extensor digitorum lies in the posterior forearm and sends four thin tendons to the back of the hand. Each tendon crosses the dorsal wrist and inserts into the extensor expansions of digits two through five, allowing them to straighten at the metacarpophalangeal joints.

It shares a common origin at the lateral epicondyle with extensor carpi ulnaris and extensor digiti minimi. The muscle is an antagonist to the flexor digitorum superficialis and flexor digitorum profundus. Its tendons spread across the dorsal hand opposite the palmaris longus slips that tighten the palmar fascia.

Related Muscles

References