Anatomy, Bony Pelvis and Lower Limb, Leg Lateral Compartment

Containing the fibularis longus muscle (FLM) and fibularis brevis muscle (FBM), common fibular and superficial fibular nerves, and branches of the anterior tibial and fibular arteries, the lateral leg compartment is one of the four compartments of the leg. Structures with the term “peroneal” have been replaced with “fibular” for anatomical accuracy. The primary function of the FLM and FBM is foot and ankle eversion, with a secondary function of foot and ankle plantarflexion and maintenance of the foot transverse and lateral arches. The anterior tibial and fibular arteries, and superficial fibular nerve provide neurovascular supply to the lateral leg compartment. The lateral leg compartment is highly variable morphologically and may have variants such as the fibularis quartus (FQ) muscle, fibularis digit quanti (FDQ), variable insertions of the fibularis brevis tendon (FBT), and supernumerary fibularis muscle bellies. Additionally, variations in the spitting of the common fibular nerve into the superficial fibular nerve and deep fibular nerve have been reported, as well as variations in the course and splitting of the superficial fibular nerve. Due to the compact nature of the lateral leg compartment, it is prone to compartment syndrome, with 13.9% to 34.4% of leg pain being associated with chronic exertional compartment syndrome (CECS). Additionally, patients may sustain acute compartment syndrome from direct trauma, inversion ankle sprains, prolonged surgical lithotomy position, and other general medical causes. Compartment syndrome can have devastating consequences if not managed appropriately, including ischemic necrosis of the lateral leg compartment structures, causing leg dysfunction and potentially leg loss. Therefore, it is important to be aware of the anatomical makeup of the lateral leg compartment, in order to understand potential pathologies and their implications on the function of the lower extremity.