The plantar fascia (plantar aponeurosis) is a broad, strong layer of connective tissue that runs along the underside of the foot from the heel bone to the base joints of the toes.
It supports the longitudinal arch of the foot and absorbs considerable tensile forces during the rolling motion of walking and running. Through the so-called windlass mechanism, the plantar fascia tightens when the toes are extended, helping to raise the arch of the foot. Overload can lead to irritation at its attachment, such as plantar fasciitis.