Deep Fibular Nerve: Course, Supply and Clinical Anatomy

By Dr Richard Miller, MBChB FRCS · Reviewed 1 October 2026

The deep fibular nerve is a terminal branch of the common fibular nerve that runs down the anterior compartment of the leg onto the dorsum of the foot. It supplies the ankle and toe extensors, including tibialis anterior, and the skin of the first web space, and travels with the anterior tibial artery on the interosseous membrane.

Deep Fibular Nerve · key facts

Origin: Common fibular nerve at the fibular neck (L4–S1 fibres)
Course: Anterior compartment on the interosseous membrane, under the extensor retinacula, onto the dorsum of the foot
Motor supply: Tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis tertius, extensor digitorum brevis, extensor hallucis brevis
Sensory supply: First web space: adjacent sides of the great and second toes
Branches: Muscular, articular to ankle, medial and lateral terminal branches
Key relations: Anterior tibial artery; between tibialis anterior and the long extensors
Injury: Foot drop without eversion loss; numb first web space

Course

The deep fibular nerve runs from the neck of the fibula, through the anterior compartment of the leg, to the dorsum of the foot, where it ends in the first web space.

Origin

It arises from the common fibular (peroneal) nerve between fibularis longus and the neck of the fibula. It passes forward through the anterior intermuscular septum and the upper part of extensor digitorum longus to enter the anterior compartment.

In the leg

The nerve joins the anterior tibial artery in the upper leg and descends with it on the interosseous membrane and then on the front of the lower tibia. It lies first between tibialis anterior and extensor digitorum longus, and lower down between tibialis anterior and extensor hallucis longus. The nerve approaches the artery from its lateral side, lies in front of it in the middle of the leg, and is lateral to it again at the ankle.

At the ankle and foot

It passes deep to the extensor retinacula midway between the malleoli, between the tendons of extensor hallucis longus and extensor digitorum longus. Just above or at the ankle it divides into two terminal branches. The lateral branch turns laterally under extensor digitorum brevis and supplies it. The medial branch continues forward on the dorsum of the foot, lateral to the dorsalis pedis artery, and pierces the deep fascia to supply the skin of the first web space.

Branches and distribution

The deep fibular nerve supplies all four muscles of the anterior compartment, the short extensors on the dorsum of the foot, and one small patch of skin.

Level	Motor	Sensory and articular
Leg	Tibialis anterior, extensor digitorum longus, extensor hallucis longus, fibularis tertius	Ankle joint
Lateral terminal branch	Extensor digitorum brevis, extensor hallucis brevis	Tarsal and metatarsophalangeal joints
Medial terminal branch	Sometimes twigs to the first dorsal interosseous	Skin of the first web space and adjacent sides of the great and second toes

Together these muscles dorsiflex the ankle, extend the toes and, through tibialis anterior, invert the foot. The skin of the first web space is the only reliable place to test deep fibular sensation, because the rest of the dorsum of the foot belongs to the superficial fibular and sural nerves.

Relations

The deep fibular nerve is the companion nerve of the anterior tibial artery and its continuation, the dorsalis pedis artery.

Upper leg: deep in the gap between tibialis anterior medially and extensor digitorum longus laterally, on the interosseous membrane.
Lower leg: between tibialis anterior and extensor hallucis longus, in front of the tibia.
Ankle: under the superior and inferior extensor retinacula, between the tendons of extensor hallucis longus medially and extensor digitorum longus laterally, with the artery on its medial side.
Foot: the medial branch lies lateral to the dorsalis pedis artery; extensor hallucis brevis crosses over both.

Clinical relevance

Deep fibular nerve injury causes foot drop with preserved eversion and numbness confined to the first web space.

Anterior compartment syndrome

The nerve runs in a tight osteofascial compartment bounded by the tibia, fibula, interosseous membrane and deep fascia. After a tibial fracture, crush injury or revascularisation, swelling raises the compartment pressure and compresses the nerve and artery. Pain out of proportion to the injury and pain on passive plantarflexion of the toes come first; numbness of the first web space is an early neurological sign. Treatment is urgent fasciotomy.

Anterior tarsal tunnel syndrome

Compression of the nerve under the inferior extensor retinaculum, from tight boot laces or ski boots, osteophytes of the talonavicular joint or swelling, causes pain on the dorsum of the foot and numbness of the first web space.

Isolated lesions

A deep fibular lesion weakens dorsiflexion and toe extension but spares eversion, because fibularis longus and brevis are supplied by the superficial fibular nerve. This separates it from a common fibular nerve palsy, in which eversion is also lost.

Regional anaesthesia

At an ankle block the deep fibular nerve is injected just lateral to the dorsalis pedis pulse, between the extensor hallucis longus and extensor digitorum longus tendons.

How it is examined

On a cadaveric spotter, in an OSPE and in MRCS Part B anatomy.

On a leg prosection, a pin on the nerve lying beside the anterior tibial artery on the interosseous membrane is the deep fibular nerve. The nerve in the lateral compartment among the fibular muscles is the superficial fibular nerve.
At the ankle, the nerve between the extensor hallucis longus and extensor digitorum longus tendons, next to the dorsalis pedis artery, is the deep fibular nerve.
Expect the sensory question: which nerve supplies the first web space (deep fibular) and why it is tested in suspected anterior compartment syndrome.
Classic look-alike: a small muscle belly on the lateral dorsum of the foot is extensor digitorum brevis, supplied by the lateral branch of the deep fibular nerve, not by the superficial fibular nerve.
Be ready to contrast deep and common fibular palsies: eversion is spared in the first and lost in the second.

Key points

The deep fibular nerve arises from the common fibular nerve at the neck of the fibula.
It runs with the anterior tibial artery on the interosseous membrane in the anterior compartment.
It supplies tibialis anterior, the long and short toe extensors and fibularis tertius.
Its only cutaneous territory is the first web space.
Anterior compartment syndrome compresses it early, causing first web space numbness.

Common questions

What does the deep fibular nerve supply?

The deep fibular nerve supplies the muscles of the anterior compartment of the leg: tibialis anterior, extensor hallucis longus, extensor digitorum longus and fibularis tertius. On the dorsum of the foot it supplies extensor digitorum brevis and extensor hallucis brevis. Its sensory supply is limited to the skin of the first web space, between the great and second toes, plus articular twigs to the ankle and foot joints.

What is the difference between the deep and superficial fibular nerves?

Both are terminal branches of the common fibular nerve at the fibular neck. The deep fibular nerve runs in the anterior compartment, supplies the dorsiflexors and toe extensors, and has sensory supply only to the first web space. The superficial fibular nerve runs in the lateral compartment, supplies fibularis longus and brevis, which evert the foot, and supplies most of the skin of the dorsum of the foot.

Why is the first web space numb in anterior compartment syndrome?

The first web space is supplied only by the deep fibular nerve, which runs through the anterior compartment of the leg. When pressure rises in that closed compartment, the nerve is compressed and its fibres stop conducting, so sensation between the great and second toes fades. Because this skin has no other supply, numbness here is a sensitive early sign that the compartment needs decompression.

References

Gray's Anatomy: The Anatomical Basis of Clinical Practice. Standring S (ed). Elsevier. 42nd edition, 2020.
Moore's Clinically Oriented Anatomy. Moore KL, Dalley AF, Agur AMR. Wolters Kluwer. 9th edition, 2022.
Last's Anatomy: Regional and Applied. Elsevier.