Lateral Intermuscular Septum

Two space compartments can be considered in the lower leg anterolateral and posteromedial. They are separated by a plane passing through the tibia, the fibular shaft, a strong interosseous membrane connecting these bones and the posterior crural intermuscular septum, vdiich is located lateral to the fibula. The anterolateral compartment can be further subdivided into an anterior crural compartment and a lateral crural compartment separated by the anterior crural intermuscular septum, located between the extensors and the peroneal muscles. The posterolateral compartment includes two groups of muscles - superficial and deep - separated by the transverse crural intermuscular septum. A brief description of the normal and US anatomy of the anterolateral and posteromedial compartments is included here. 

Muscle hernias are focal protrusions of muscle tissue through fascial defects. In the lower leg, herniation of muscle is most commonly observed in the middle and lower thirds affecting the tibialis anterior muscle, although involvement of the extensor digitorum longus, peroneal muscles and the lateral head of the gastrocnemius have also been reported (Mellado and Perez del Palomar 1999). The area overlying the anterior intermuscular septum. 

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