Muscle · Foot

Quadratus plantae

Musculus quadratus plantae

A small, flat muscle in the sole with an unusually clever job. The long toe flexor enters the foot from the inside of the ankle, so it pulls the toes inward and off-line rather than straight back. This muscle grabs that tendon and pulls it straight, correcting the angle so the toes curl cleanly rather than drifting toward the arch. It also lets the toes keep gripping when the ankle is pointed and the long flexor has run out of usable pull. It is one of the reasons toe grip stays strong throughout a step rather than only at one ankle angle.