Extensor digitorum longus muscle
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The extensor digitorum longus is a long, thin muscle situated in the anterior compartment of the leg. Alongside the tibialis anterior and the extensor hallucis longus, the extensor digitorum longus is known as one of the leg extensors.
origin: medial aspect of proximal fibula, lateral tibial condyle, interosseous membrane of the leg
insertion: distal and middle phalanges of 2nd to 5th toes
action: extends the lateral four toes, foot dorsiflexion
innervation: deep peroneal nerve (L5 - S1)
The extensor digitorum longus is the most lateral muscle in the extensor compartment of the leg. It lies lateral to the tibialis anterior and extensor hallucis longus, with the anterior tibial artery and vein passing between the extensor digitorum longus and the tibialis anterior.
The extensor digitorum longus originates from the inferior aspect of the lateral tibial condyle, the proximal half of the anteromedial surface of the fibula, and the superior anterior surface of the interosseous membrane.
The muscle splits into four distinct tendons within the inferior extensor retinaculum, which descend deep to the superior extensor retinaculum. These tendons insert on the distal and middle phalanges of the 2nd to 5th digits to form the dorsal digital expansions (or extensor hoods). Each dorsal aponeurosis 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