Extensor hallucis brevis is a part of the extensor digitorum brevis muscle of the foot, but some sources consider it to be a separate muscle.
In continuity with extensor digitorum brevis, it arises from the lateral and superior surface of the calcaneus. It passes anteriorly and medially to insert into the dorsal base of the proximal phalanx of the great toe.
It acts to extend the fully flexed great toe.
Extensor hallucis brevis is innervated by the deep peroneal nerve (L5, S1).