Origin: 2 heads, the medial surface and the lateral border of the inferior surfaces of the calcaneus;
  Insertion: fuses with the tendon of the flexor digitorum longus;
  Action: flexes the 2nd to 5th toes;
  Nerve Supply: Lateral plantar,  S1, S2; (See Innerv. Musc. Lower Limb )
  Synergists: flexor digitorum longus, flexor digitorum brevis.
 

Why does man have a quadratus plantae? A review of its comparative anatomy