Muscle · Lower leg

Flexor digitorum longus

Musculus flexor digitorum longus

The long muscle that curls the outer four toes. It runs down the back of the shin bone, slips behind the inside of the ankle, then crosses the sole and splits into four tendons, one for each of the small toes. Its job is grip: as you take weight it presses the toes into the ground, which widens your base and steadies the foot, and it helps hold the arch up while it does so. Weak toe grip shows up as poor balance and a foot that has nothing to push off with — which is why toe flexion is worth testing whenever someone reports feeling unsteady.