Quadratus Plantae Muscle
The quadratus plantæ (flexor accessorius) is separated from the muscles of the first layer by the lateral plantar vessels and nerve. It acts to aid in flexing the 2nd to 5th toes (offsetting the oblique pull of the flexor digitorum longus) and is one of the few muscles in the foot with no homolog in the hand.
Read more about Quadratus Plantae Muscle: Origin and Insertion, Variations, Additional Images