Flexor Digitorum Brevis: The flexor digitorum brevis muscle lies in the middle of the sole of the foot. Its exact location is within the sole of the foot, directly over the plantar aponeurosis, which supports the arch of the foot.
Origin: Medial process of calcaneal tuberosity and plantar aponeurosis.
Insertion: Plantar sides of middle phalanges of lateral four toes
Function: Flexes lateral four toes at proximal interphalangeal joint
Nerve Supply: Medial plantar nerve from the tibial nerve.