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.
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Summary
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
blood supply: branches of anterior tibial and fibular arteries
innervation: deep peroneal nerve (L5 - S1)
Gross anatomy
Relations
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.
Origin
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.
Insertion
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
Action
The extensor digitorum longus muscle provides foot dorsiflexion at the talocrural joint and extension of the toes at the 2nd to 5th metatarsophalangeal and interphalangeal joints.
Arterial supply
The proximal part of the muscle receives blood supply from the anterior tibial artery, while the distal part is supplied by the fibular artery.
Innervation
The extensor digitorum longus is innervated by the deep peroneal nerve (L4 - S1), a branch of the common peroneal nerve.
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