Beneath the skin and subcutaneous tissue of the sole lies the plantar aponeurosis. This fibrous structure is (in lower mammals) an expansion of the tendon of the calf muscle plantaris. In man it has become detached and acts as a major "tie beam" for the longitudinal arches of the foot.
Expansions at each side cover abductors of the big and little toe (see below).
|When the toes are raised (extended) the plantar aponeurosis becomes taut and the arches of the foot become rigidly braced. This happens during walking at "push off".|