The common fibular nerve (also known as the common peroneal nerve, external popliteal nerve, or lateral popliteal nerve) is a nerve in the lower leg that provides sensation over the posterolateral part of the leg and the knee joint. It divides at the knee into two terminal branches: the superficial fibular nerve and deep fibular nerve, which innervate the muscles of the lateral and anterior compartments of the leg respectively. When the common fibular nerve is damaged or compressed, foot drop can ensue. Structure The common fibular nerve is the smaller terminal branch of the sciatic nerve. The common fibular nerve has root values of L4, L5, S1, and S2. It arises from the superior angle of the popliteal fossa and extends to the lateral angle of the popliteal fossa, along the medial border of the biceps femoris. It then winds around the neck of the fibula to pierce the fibularis longus and divides into terminal branches of the superficial fibular nerve and the deep fibular nerve. Before its division, the common fibular nerve gives off several branches in the popliteal fossa. Cutaneous branches Lateral sural cutaneous nerve (lateral cutaneous nerve of calf) - supplies the skin of the upper two-thirds of the lateral side of leg. sural communicating nerve - it runs on the posterolateral aspect of the calf and joins the sural nerve. Articular branches Superior lateral genicular nerve - accompanies artery of the same name and lies above the lateral femoral condyle. Inferior lateral genicular nerve - accompanies artery of the same name and lies just above the head of the fibula. Recurrent genicular nerve - It arises from the point of division of the common fibular nerve; then ascends anterior to the knee joint together with the anterior recurrent tibial artery to supply the knee joint and the tibialis anterior muscle. Motor branches There is only one motor branch that arises directly from the common fibular nerve, the nerve to the short head of the biceps femoris muscle. Function The common fibular nerve innervates the short head of the biceps femoris muscle via a motor branch that exits close to the gluteal cleft. The remainder of the fibular-innervated muscles are innervated by its branches, the deep fibular nerve and superficial fibular nerve. It provides sensory innervation to the skin over the upper third of the lateral aspect of the leg via the lateral sural cutaneous nerve.