The leg, is the region of the lower limb between the knee and the ankle.

It is a tightly packed region consisting of muscles and neurovascular structures.

The leg is organized into three fascial compartments: anterior, lateral, and posterior, which are formed by the interosseous membrane, the anterior intermuscular septum, and posterior intermuscular septum.

The anterior compartment of the leg is also known as the extensor or dorsiflexor compartment, and it’s the area of the body you use to locate the furniture after you turn off the lights.

Ouch! It is bounded anteriorly by the deep fascia of the leg and skin, posteriorly by the interosseous membrane, medially by the lateral surface of the tibia, and laterally by the anterior intermuscular septum and the medial surface of the fibula..

Now, proximally, the deep fascia overlying the anterior compartment is dense, providing part of the proximal attachment of the muscle immediately deep to it, the tibialis anterior.

Distally, the deep fascia presents two band-like thickenings organized as two retinacula.

Retinacula help secure and provide leverage for the tendons of the anterior compartment muscles before and after they cross the ankle joint.

Specifically, the retinacula prevent these tendons from bowstringing anteriorly during movement of the joint.

First, there’s the superior extensor retinaculum, which is a strong, broad band of deep fascia, passing from the fibula to the tibia, proximal to the malleoli.

Second, there’s the inferior extensor retinaculum, a Y-shaped band of deep fascia that attaches laterally to the anterosuperior surface of the calcaneus and medially to the medial malleolus and medial cuneiform. It forms a strong loop around the tendons of the fibularis tertius and the extensor digitorum longus muscles.

The anterior compartment contains four muscles: the tibialis anterior, extensor digitorum longus, extensor hallucis longus, and fibularis tertius which are all dorsiflexors of the ankle, raising the toes and depressing the heel.

To remember dorsiflexion, think of the phrase ‘fins to shins’, with your toes being the fins you use to swim, and you are bringing them up to your shins!