ABSTRACT
The musculature of the lower leg is enclosed in four tight, inflexible compartments by fascias of connective tissue which are anchored to the tibia and fibula. A cross-section through the lower leg about 4 in (10 cm) below the knee shows that the four compartments are clearly defined. In front, between the tibia and the fibula, there is an anterior compartment which contains the toe extensors, the tibialis anterior muscle, and the blood vessels and nerves that supply the anterior aspect of the lower leg and foot. At the back, the lower leg is divided into two compartments, one deep and one superficial. The deep one, which is located between the tibia and the fibula and behind the tight connective tissue band (interosseous membrane) that connects the two, contains the long toe flexors (flexor digitorum longus and flexor hallucis longus) and the tibialis posterior muscle. Nerves and blood vessels pass to the back of the lower leg and the sole of the foot through this deep compartment. The posterior superficial muscle compartment at the back contains the broad, deep calf muscle (the soleus) and the superficial calf muscle (the gastrocnemius). On the lateral aspect of the leg,
around the fibula, is a lateral compartment which encloses the peroneus longus, the peroneus brevis and the peroneal nerve.
