Abductor digiti minimi
Abductor digiti minimi is the most lateral muscle in the first layer of the plantar region of the foot. It arises from both processes of the calcaneal tuberosity, as well as the plantar fascia and it inserts distally into the lateral side of the base of the proximal phalanx of the 5th toe.
Its action is similar to that of abductor hallucis - flexion and abduction. Abductor digiti minimi obviously performs these actions on the 5th toe. To test the function of abductor digiti minimi, place two fingers along the plantar-lateral aspect of the 5th metatarsal shaft and ask your subject to abduct or flex their 5th digit against resistance.