Extensor Digitorum Brevis
Foot · Lower Limb
The extensor digitorum brevis is a small muscle on the dorsum of the foot, the only muscle located entirely on the dorsal surface. It arises from the superolateral surface of the calcaneus and the inferior extensor retinaculum, and its fleshy belly gives rise to tendons that pass to the lateral sides of the long extensor tendons and the bases of the proximal phalanges of the second to fourth toes. It extends these toes at the metatarsophalangeal and interphalangeal joints, assisting the long extensors and improving the leverage of extension when the ankle is dorsiflexed. It is supplied by the deep fibular nerve (S1, S2). Its rounded belly forms a soft swelling on the lateral dorsum of the foot that should not be mistaken for oedema.
Origin, Insertion, Action & Nerve
Origin
Superolateral surface of the calcaneus and the inferior extensor retinaculum
Insertion
Lateral sides of the long extensor tendons / bases of the proximal phalanges of toes 2–4
Action
Extends toes 2–4 at the metatarsophalangeal and interphalangeal joints
Nerve
Deep fibular nerve (S1–S2)
Attachments explained
The Extensor Digitorum Brevis is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Superolateral surface of the calcaneus and the inferior extensor retinaculum
Insertion
Lateral sides of the long extensor tendons / bases of the proximal phalanges of toes 2–4
Action & function
When the Extensor Digitorum Brevis contracts, it produces the following movement: Extends toes 2–4 at the metatarsophalangeal and interphalangeal joints.
As part of the Foot group of the Lower Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Extensor Digitorum Brevis receives its nerve supply from the Deep fibular nerve (S1–S2). This nerve carries fibres from spinal segment(s) S1, S2.
Because a muscle can only contract when its nerve is intact, injury to the Deep fibular nerve or to its spinal roots (S1, S2) can weaken or paralyse the Extensor Digitorum Brevis, impairing the movements it normally produces (extends toes 2–4 at the metatarsophalangeal and interphalangeal joints). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Extensor Digitorum Brevis (the OIANS method)
Learn the extensor digitorum brevis as the short extensor that lives on the back of the foot itself, arising from the calcaneus rather than the leg. Because it lies dorsally and blends with the long extensor tendons, it reinforces extension of toes two through four; its most medial slip to the great toe is often named separately as the extensor hallucis brevis.
Fix its clinical value and nerve: its fleshy belly on the lateral dorsum forms a soft mound that distinguishes swelling from a bruise, and its wasting is a sign in deep fibular nerve lesions. Remembering that it shares the deep fibular nerve (S1, S2) with the anterior compartment ties this intrinsic foot muscle back to the extensor group that continues into it.
Frequently asked questions
Where is the Extensor Digitorum Brevis located?
The Extensor Digitorum Brevis is a muscle of the Foot group, located in the Lower Limb.
What is the origin of the Extensor Digitorum Brevis?
Superolateral surface of the calcaneus and the inferior extensor retinaculum
What is the insertion of the Extensor Digitorum Brevis?
Lateral sides of the long extensor tendons / bases of the proximal phalanges of toes 2–4
What movements does the Extensor Digitorum Brevis produce?
Extends toes 2–4 at the metatarsophalangeal and interphalangeal joints
What nerve supplies the Extensor Digitorum Brevis?
Deep fibular nerve (S1–S2)
Is the Extensor Digitorum Brevis free to study in OIANS?
The Extensor Digitorum Brevis is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Lower Limb is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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