Extensor digitorum longus muscle

Extensor digitorium longus (EDL) is a thin muscle situated in the anterior leg lateral to extensor hallucis longus and extends the lateral four toes.

Summary

• origin: lateral tibial condyle, medial surface of the middle portion of the fibula and superior portion of the anterior surface of the interosseous membrane
• insertion: dorsal aponeurosis on the dorsal surface of the proximal phalanges of the 2^nd, 3^rd, 4^th and 5^th toes. Each dorsal aponeurosis then divides into a central band and two lateral bands:
  • the central band inserts into the base of the middle phalanx
  • the lateral bands insert into the medial and lateral surfaces of the base of the distal phalanx
• action: extends the lateral four toes
• arterial supply: anterior tibial artery
• innervation: deep peroneal nerve
• key relationships: lateral to extensor hallucis longus and shares a common tendon sheath with peroneus tertius

Gross anatomy

The muscle divides into four distinct tendons above the ankle joint which descend deep to the superior extensor retinaculum. As these tendons pass deep to the inferior extensor retinaculum, they are enclosed in a common tendon sheath with peroneus tertius.