Fascia · Lower leg

Anterior intermuscular septum

Septum intermusculare cruris anterius

A thin vertical wall inside the lower leg, running from the deep surface of the leg's fascial sleeve down to the front border of the fibula. It is the divider between two compartments: in front of it sit the muscles that lift the foot and toes, behind it the fibularis muscles that turn the sole outward. Both sets take part of their origin from its two faces, so it is a working attachment surface rather than a passive partition. The superficial fibular nerve runs down the lateral compartment against its back face before piercing the deep fascia of the leg in the lower third to reach the skin of the foot.