The quadratus plantae is a muscle in the foot that extends from the anterior (front) of the calcaneus (heel bone) to the tendons of the digitorum longus muscle in the leg. It assists the flexor digitorum longus with toe flexing. The muscle brings the pulley of the flexor digitorum longus in line with the length of the foot. The quadratus plantae muscle also increases stability of the foot by resisting extension of the toes.
When the muscle is not functioning properly it can be a cause of heel pain and claw toe deformity. Diabetic polyneuropathy (a type of nerve damage that may occur as a complication of diabetes) may cause pain and tingling in the muscle.