Extensor hallucis brevis muscle
Extensor hallucis brevis is a short muscle located in the dorsum of the foot, attaching between the calcaneus and proximal phalanx of the big toe (hallux). Along with the extensor digitorum brevis, it belongs to the group of dorsal foot muscles. Sometimes, the fibers of these two muscles fuse, making a single muscle that extends the toes.
In this article, we will discuss the anatomy and function of the extensor hallucis brevis muscle.
|Origin||Superolateral surface of calcaneus bone|
|Insertion||Proximal phalanx of great toe|
|Action||Metatarsophalangeal joint 1: Toe extension|
|Innervation||Deep fibular/peroneal nerve (S1, S2)|
|Blood supply||Dorsal artery of foot|
Origin and inserton
The short and slender extensor hallucis brevis muscle sits in the lateral aspect of the dorsum of foot. It originates from the superior aspect of calcaneus, just posteriorly to calcaneocuboid joint. It courses medially over the dorsum of the foot, giving off a tendon that inserts onto the base of proximal phalanx of hallux.
Lying medially to extensor digitorum longus, extensor hallucis brevis is the most medial dorsal foot muscle. Together with the rest of the structures found in this foot compartment, extensor hallucis brevis is covered by the deep layer of fascia of foot, which is a continuation of the deep fascia of leg (crural fascia). Within the dorsal foot compartment itself, extensor hallucis brevis courses deep to the inferior flexor retinaculum and extensor digitorum longus tendons, while it covers the dorsalis pedis artery and deep fibular (peroneal) nerve.
The bellies of the extensor digitorum brevis and extensor hallucis longus form a small prominence anteriorly to the lateral malleolus. This elevation is notable and easily palpable when both muscles are active.
Extensor hallucis brevis is innervated by the deep fibular (peroneal) nerve (root value L5-S1).
The blood supply for extensor hallucis brevis muscle comes from the dorsal artery of foot, which is a continuation of the anterior tibial artery.
Acting together with the extensor hallucis longus, this muscle extends the hallux at the metatarsophalangeal joint. This action results in returning the hallux from the flexed into the neutral position, or in pulling it above the ground if the contraction continues (hyperextension). This movement is important in gait, as raising the big toe clear of the ground facilitates walking and running.
To expand your knowledge check out our study unit about the dorsal muscles of foot.