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# Extensor digitorum brevis

The extensor digitorum brevis is a small muscle on top of the foot that helps lift the toes; its soft bulge is normal.

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## What it is

A small, flat muscle on top of the foot, starting on the heel bone. With the extensor hallucis brevis, it is the only muscle on top of the foot.

## What it does

Helps the long tendons lift the toes.

## Key points

- Its soft belly in front of the lateral malleolus is a normal bulge that can be mistaken for swelling or a mass
- The usual recording site for motor nerve conduction studies of the fibular nerve
- Supplied by the lateral terminal branch of the deep fibular nerve; in some people an accessory deep fibular nerve, from the superficial fibular nerve, also supplies it
- No tendon goes to the [little toe](https://durgical.com/en/anatomy/little-toe/); its tendons for toes 2–4 join the long [extensor tendons](https://durgical.com/en/anatomy/extensor-digitorum-tendons/) on their lateral side

## Key facts

**Origin**
Superolateral calcaneus (floor of sinus tarsi); inferior extensor retinaculum

**Insertion**
Long extensor tendons of toes 2–4

**Action**
Helps extend toes 2–4

**Nerve**
Deep fibular nerve (L5–S1) (some texts: S1–S2)

**Blood supply**
Dorsalis pedis artery (lateral tarsal branch); perforating branch of [fibular artery](https://durgical.com/en/anatomy/fibular-artery/)

## Relations

**Deep**
[Calcaneus](https://durgical.com/en/anatomy/calcaneus/) and the sinus tarsi, the lateral tarsal bones and the lateral tarsal artery

**Superficial**
[Extensor digitorum longus](https://durgical.com/en/anatomy/extensor-digitorum-longus/) and [fibularis tertius](https://durgical.com/en/anatomy/fibularis-tertius-muscle/) tendons, the inferior [extensor retinaculum](https://durgical.com/en/anatomy/extensor-retinaculum-of-the-wrist/) and dorsal branches of the [superficial fibular nerve](https://durgical.com/en/anatomy/superficial-fibular-nerve/)

**Medial**
[Extensor hallucis brevis](https://durgical.com/en/anatomy/extensor-hallucis-brevis/) (its medial part), then the [dorsalis pedis artery](https://durgical.com/en/anatomy/dorsalis-pedis-artery/) and the [deep fibular nerve](https://durgical.com/en/anatomy/deep-fibular-nerve/)

**Lateral**
The fibular tendons, which curve below the lateral malleolus behind and below the muscle

## How to find it

With the toes extended, a soft, rounded belly appears on the dorsolateral foot just in front of and below the lateral malleolus, over the sinus tarsi.

## Examination

- Nerve conduction: a small or absent motor response recorded over it suggests a common or deep fibular nerve lesion; extra response on stimulating behind the lateral malleolus points to an accessory deep fibular nerve
- Wasting, seen as a hollow in front of the lateral malleolus, suggests a long-standing fibular nerve or L5–S1 root problem

## On imaging

Ultrasound and MRI show it as a small muscle belly on the dorsolateral foot, in front of the lateral malleolus over the sinus tarsi. Its normal bulge is often referred for a suspected soft-tissue mass, and imaging confirms ordinary muscle. Fatty atrophy of the belly on MRI supports a chronic deep fibular nerve lesion.

## Clinical notes

- It is lifted from its origin in the lateral (sinus tarsi) approach to the subtalar joint and calcaneus
- After resection of a calcaneonavicular coalition, it is often placed into the gap to stop the bar from re-forming
- Can be used as a small local muscle flap for defects over the lateral ankle

## Anatomical variants

- An accessory deep fibular nerve, a branch of the superficial fibular nerve passing behind the lateral malleolus, supplies part of the muscle in some people

## Test yourself

Think of the answer, then tap the question to see it.

## What are the origin and nerve supply of the extensor digitorum brevis?

Superolateral calcaneus (floor of the sinus tarsi) and inferior extensor retinaculum; deep fibular nerve.

## Why is the extensor digitorum brevis important in nerve conduction studies?

It is the usual recording site for motor conduction of the fibular nerve; a small or absent response suggests a common or deep fibular lesion.

## What variant nerve may also supply the extensor digitorum brevis?

An accessory deep fibular nerve, a branch of the superficial fibular nerve passing behind the lateral malleolus.

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Educational information, not medical advice. For any symptom, see a health professional.

## Its names

**Official Latin (TA2)**
extensor brevis digitorum TA2 2671

**Official Spanish (DeCS)**
Músculo extensor corto de los dedos

**English (TA2)**
Extensor digitorum brevis

**Also called**
extensor digitorum brevis muscle

## Related

- [Toe extensor tendons](https://durgical.com/en/anatomy/tendons-of-extensor-digitorum-longus/)
- [Extensor hallucis brevis](https://durgical.com/en/anatomy/extensor-hallucis-brevis/)
- [Deep fibular nerve](https://durgical.com/en/anatomy/deep-fibular-nerve/)
- [Top-of-foot arteries](https://durgical.com/en/anatomy/arcuate-artery/)
- [Calcaneus](https://durgical.com/en/anatomy/calcaneus/)
- [Cuboid](https://durgical.com/en/anatomy/cuboid-bone/)
- [Lateral cuneiform](https://durgical.com/en/anatomy/lateral-cuneiform-bone/)
- [Second metatarsal](https://durgical.com/en/anatomy/second/)

Sources: Terminologia Anatomica (TA2); [Anatomy, Bony Pelvis and Lower Limb, Foot Muscles](https://www.ncbi.nlm.nih.gov/books/NBK539705/).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/anatomy/extensor-digitorum-brevis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/extensor-digitorum-brevis/