The external popliteal, or common peroneal, rises from the bifurcation of the great sciatic in the lower part of the thigh. It passes along the lateral aspect of the popliteal space, parallel to the biceps tendon. After running between the biceps and the lateral head of the gastrocnemius, it winds round the neck of the fibula, enters the peroneus longus, and divides into musculo-cutaneous (superficial peroneal), the anterior tibial (deep peroneal), and the recurrent tibial.
(a) Muscular, to the short head of the biceps.
(b) Articular, one or two branches to the knee-joint.
(c) Recurrent tibial, supplying the upper part of the tibialis anticus, the superior tibio-fibular joint, and the knee-joint.
(d) Cutaneous, two in number, a lateral cutaneous branch, and the ramus communicans fibularis. The former innervates the skin over the lateral aspect of the upper two thirds of the back of the leg. The communicans fibularis joins the communicans tibialis of the internal popliteal to form the lateral or short saphenous. This nerve, in company with the short saphenous vein, passes downwards, behind the lateral malleolus to terminate on the lateral side of the little toe. It is distributed to the skin of the lower third of the back of the leg, together with the lateral aspect of the foot and little toe. Articular twigs are furnished to the ankle and tarsal joints.
(e) Anterior tibial. (f) Musculo-cutaneous.