[TA] intrinsic muscle of dorsum of foot considered by some anatomists as the medial belly of the extensor digitorum brevis muscle; origin, dorsal calcaneus; insertion, via a stout tendon into the dorsal aspect of the base of the proximal phalanx of the great toe; action, extends great toe; nerve supply, deep fibular. SYN: musculus extensor hallucis brevis [TA], short extensor (muscle) of great toe.