Extensor Hallucis Brevis
Foot · Lower Limb
The extensor hallucis brevis is a short muscle on the dorsum of the foot, functionally the most medial slip of the extensor digitorum brevis. It arises from the superolateral surface of the calcaneus and the inferior extensor retinaculum, then passes forward and medially to insert on the dorsal base of the proximal phalanx of the great toe. Its action is to extend the great toe at the metatarsophalangeal joint, assisting the long extensor (extensor hallucis longus) especially when the foot is dorsiflexed. It is supplied by the deep fibular nerve (S1-S2), the same nerve that drives the other dorsal foot extensor and the anterior compartment of the leg. Because its fleshy belly lies just lateral to the extensor hallucis longus tendon, it contributes to the soft mound felt on the front of the ankle and forefoot.
Origin, Insertion, Action & Nerve
Origin
Superolateral surface of the calcaneus and the inferior extensor retinaculum
Insertion
Dorsal base of the proximal phalanx of the great toe
Action
Extends the great toe at the metatarsophalangeal joint
Nerve
Deep fibular nerve (S1–S2)
Attachments explained
The Extensor Hallucis 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
Dorsal base of the proximal phalanx of the great toe
Action & function
When the Extensor Hallucis Brevis contracts, it produces the following movement: Extends the great toe at the metatarsophalangeal joint.
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 Hallucis 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 Hallucis Brevis, impairing the movements it normally produces (extends the great toe at the metatarsophalangeal joint). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Extensor Hallucis Brevis (the OIANS method)
Learn this muscle as the great-toe member of the extensor digitorum brevis family. Both share the same origin on the superolateral calcaneus and the same deep fibular nerve, so once you place the belly on the dorsum of the foot and trace it to the base of the great toe's proximal phalanx, its single action of extending that toe at the MTP joint follows directly from the line of pull.
Distinguish it from the long extensor by depth and reach. Extensor hallucis longus comes from the fibula and interosseous membrane and reaches the distal phalanx, whereas the brevis is intrinsic to the foot and stops at the proximal phalanx. Remembering that both answer to the deep fibular nerve lets you predict that a lesion of that nerve weakens great-toe extension from two sources at once.
Frequently asked questions
Where is the Extensor Hallucis Brevis located?
The Extensor Hallucis Brevis is a muscle of the Foot group, located in the Lower Limb.
What is the origin of the Extensor Hallucis Brevis?
Superolateral surface of the calcaneus and the inferior extensor retinaculum
What is the insertion of the Extensor Hallucis Brevis?
Dorsal base of the proximal phalanx of the great toe
What movements does the Extensor Hallucis Brevis produce?
Extends the great toe at the metatarsophalangeal joint
What nerve supplies the Extensor Hallucis Brevis?
Deep fibular nerve (S1–S2)
Is the Extensor Hallucis Brevis free to study in OIANS?
The Extensor Hallucis 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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