Dorsum of foot

Question 1

Extensor digitorum brevis:
* Origin
* Insertion
* Nerve supply
* Action

Answer 1

• Origin - arises from the upper and lateral surface of the calcaneus and the stem of the inferior extensor retinaculum.
• Insertion - inserts via tendons into the base of the proximal phalanx of the 1st toe, and the middle phalanx of the three medial digits joining with the extensor digitorum longus tendon (toes 2-4).
• Nerve supply - deep peroneal nerve (S1, 2).
• Action - extend the metatarsophalangeal and interphalangeal joints of the 2nd, 3rd and 4th toes. It also assists extensor hallucis longus in 1st toe metatarsophalangeal extension.