Deep fibular nerve

At a glance

English

Deep fibular nerve

Latin (TA2)

Nervus fibularis profundus

System

Nerve

Region

Lower limb

Side

Paired, left and right

About the deep fibular nerve

The deep fibular (deep peroneal) nerve serves the anterior, extensor compartment of the leg and of the short extensors on top of the foot. It begins where the common fibular nerve divides, lateral to the neck of the fibula and under the upper part of fibularis longus. It is often compared with the posterior interosseous nerve of the forearm, which plays the same role for the extensors there.

From its start the nerve runs downwards and inwards, piercing the anterior intermuscular septum and then extensor digitorum longus, to reach the front of the interosseous membrane. There it meets the anterior tibial artery, lying lateral to it at first, and the two descend together, between tibialis anterior and extensor digitorum longus higher up and between tibialis anterior and extensor hallucis longus lower down. The nerve passes under the extensor retinacula and splits in front of the ankle into a medial and a lateral terminal branch.

In the leg it supplies tibialis anterior, extensor digitorum longus, extensor hallucis longus and fibularis tertius, and gives an articular twig to the ankle. The lateral terminal branch turns outwards across the tarsus deep to extensor digitorum brevis, supplying that muscle and extensor hallucis brevis, and swells into a small pseudoganglion from which fine twigs go to the tarsal joints and the joints at the bases of the middle toes. The medial terminal branch follows the dorsalis pedis artery to the first intermetatarsal space, sends a twig to the first dorsal interosseous and the great toe's metatarsophalangeal joint, and ends as two dorsal digital nerves for the facing sides of the first and second toes.

Loss of this nerve, as in lateral knee trauma or compartment syndrome of the anterior leg, causes foot drop, because the foot can no longer be pulled up. Diabetes, poor blood supply and inflammation can also affect it. Sensory loss is limited to the first web space, which is a useful test. At the ankle it can be compressed beneath the extensor retinaculum or by tight shoe straps (anterior tarsal tunnel syndrome), giving pain and tingling between the first two toes; releasing the tissue that presses on it relieves this.

Course and supply

Arises from

The common fibular nerve, at its division lateral to the neck of the fibula beneath fibularis longus.

Ends in

Medial and lateral terminal branches at the ankle; the medial ends as dorsal digital nerves to the adjacent sides of the first and second toes.

Supplies

Motor to tibialis anterior, extensor digitorum longus, extensor hallucis longus, fibularis tertius, extensor digitorum brevis and extensor hallucis brevis; sensory to the first web space and the ankle and tarsal joints.