CorpusHuman Anatomy
MuscularMuscle

Extensor digitorum longus

Musculus extensor digitorum longus

Also known as: EDL, fibularis tertius, peroneus tertius

The most lateral anterior-compartment muscle, a unipennate muscle that extends the lateral four toes and dorsiflexes the ankle. Its lateral slip often forms fibularis tertius.

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Overview

EDL arises from the lateral condyle of the tibia, the upper three-quarters of the anterior surface of the fibula and the interosseous membrane. It is unipennate. Its tendon passes under the extensor retinacula, lateral to EHL, and divides into four slips. These form extensor expansions on the dorsum of toes 2–5 and insert on their middle and distal phalanges.

A partly separate lower slip, fibularis (peroneus) tertius, present in most people, inserts on the dorsal base of the 5th metatarsal. It dorsiflexes and everts the foot. EDL extends the lateral four toes and dorsiflexes the ankle. It is supplied by the deep fibular nerve.

Parts & subdivisions

  1. Four digital tendons
    To the extensor expansions of toes 2–5.
  2. Fibularis tertius
    Lower lateral slip to the base of the 5th metatarsal. Dorsiflexes and everts.

Anatomy

Origin

Lateral condyle of the tibia, upper three-quarters of the anterior surface of the fibula and the interosseous membrane.

Insertion

Middle and distal phalanges of the lateral four toes (via the extensor expansions).

Action

Extension of the lateral four toes; dorsiflexion of the ankle.

Innervation

Deep fibular nerve.

Nerve roots

L5–S1

Arterial supply

Anterior tibial artery.

Relations

Lies lateral to tibialis anterior and EHL, and anterior to the fibularis muscles (separated by the anterior intermuscular septum).

Function

  • Extends toes 2–5
  • Dorsiflexes the ankle
  • Everts the foot (with fibularis tertius)

Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.