Sural nerve

At a glance

English

Sural nerve

Latin (TA2)

Nervus suralis

System

Nerve

Region

Lower limb

Side

Paired, left and right

About the sural nerve

The sural nerve takes its name from the sura, the calf. It is a cutaneous nerve with no motor fibres, made by the union of two branches from the popliteal fossa: the tibial nerve's medial sural cutaneous branch and the common fibular nerve's sural communicating branch, which usually leaves the lateral sural cutaneous nerve or the common fibular nerve itself. Where and how these branches join, and how much each contributes, varies a good deal, and can differ between a person's two legs.

The medial sural cutaneous nerve leaves the tibial nerve in the fossa and runs down in the groove between the two heads of gastrocnemius, beneath the deep fascia. About the middle of the calf it pierces the fascia, and there or lower it is joined by the fibular communicating branch to form the sural nerve proper.

From mid-calf downwards the nerve lies close beneath the skin with the small saphenous vein, following a line from the middle of the back of the knee to just behind the lateral malleolus. It passes behind and below the malleolus, near the sheath of the fibular tendons, and continues forwards along the lateral edge of the foot as the lateral dorsal cutaneous nerve, ending near the base of the fifth metatarsal and the outer side of the little toe. It supplies the skin of the lower back and outer side of the leg, the lateral heel and ankle, and the lateral border of the foot and fifth toe, and links with the intermediate dorsal cutaneous branch of the superficial fibular nerve.

Because removing it leaves only a small numb patch on the outside of the foot, this nerve is the usual site for nerve biopsy and the commonest donor for nerve grafts elsewhere. It is affected early in many length-dependent peripheral neuropathies, which makes it a standard nerve for conduction studies, and occasionally it is selectively involved in inflammatory or vasculitic disease. A sural mononeuropathy is unusual and most often follows trauma, Achilles tendon surgery or a ganglion; it gives tingling or burning along the outer foot. Its superficial course behind the lateral malleolus makes it easy to block for foot and ankle surgery.

Course and supply

Arises from

Formed in the calf where the tibial nerve's medial sural cutaneous branch meets the sural communicating branch (common fibular).

Ends in

Continues behind the lateral malleolus as the lateral dorsal cutaneous nerve along the outer border of the foot to the fifth toe.

Supplies

Purely sensory to the skin of the lower posterolateral leg, lateral heel and ankle, and the lateral side of the foot and little toe.