Quadratus plantaris muscle

Beginning: tibial and plantar surface at the tuber calcanei

Attachment: the outer edge of the tendon flexor digitorum longus muscle

Innervation: n. plantaris lateralis (branch of tibial nerve)(S1–S2)

Function: flexion of the distal joints of the fingers (auxiliary muscle for flexor digitorum longus muscle - balances the oblique pull of this muscle)