Extensor Hallucis Brevis (Musculus extensor hallucis brevis)
Educational content only — not medical advice.
Anatomy
The medial slip of the extensor digitorum brevis group on the dorsum of the foot. It runs from the dorsal calcaneus, under the tendons of the long extensors, to the base of the proximal phalanx of the great toe, and acts almost exclusively on the metatarsophalangeal joint — complementing the long extensor, which acts chiefly on the interphalangeal joint.
Origin & insertion
From the superior surface of the anterior calcaneus, distal to the origin of the extensor digitorum brevis, to the dorsal base of the proximal phalanx of the great toe.
Action
Extends the metatarsophalangeal joint of the great toe.
Innervation
Deep peroneal (fibular) nerve (L5–S1).
Clinical notes
Weakness or atrophy of this muscle is the clinical probe of the deep peroneal nerve at the dorsum: denervation here accompanies anterior-compartment and ankle-level palsies, while the belly itself is the site sought when palpating for an EHB flick in the "toe sign".
Related structures
Educational references
FAQ
What is the role of the Extensor Hallucis Brevis?
The medial slip of the extensor digitorum brevis group on the dorsum of the foot. It runs from the dorsal calcaneus, under the tendons of the long extensors, to the base of the proximal phalanx of the great toe, and acts almost exclusively on the metatarsophalangeal joint — complementing the long extensor, which acts chiefly on the interphalangeal joint.
Why is the Extensor Hallucis Brevis clinically important?
Weakness or atrophy of this muscle is the clinical probe of the deep peroneal nerve at the dorsum: denervation here accompanies anterior-compartment and ankle-level palsies, while the belly itself is the site sought when palpating for an EHB flick in the "toe sign".
Source & license
BodyParts3D, © The Database Center for Life Science licensed under CC Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/). license details