Fascia · Foot

Plantar fascia

Aponeurosis plantaris

A tough fibrous sheet under the sole, running from the inner heel forward and fanning out into the base of the toes. It works like a bowstring across the arch: when the toes extend as you push off, the fascia winds around the joints and pulls the arch up, turning a soft foot into a rigid lever. That is the windlass mechanism, and it is why the fascia is loaded most at the moment you leave the ground rather than when you land. Heel pain here is typically a load-tolerance problem at the point where the fascia meets the heel bone.