Tibial nerve

At a glance

English

Tibial nerve

Latin (TA2)

Nervus tibialis

System

Nerve

Region

Lower limb

Side

Paired, left and right

About the tibial nerve

The tibial nerve carries fibres from L4 to S3 and continues the line of the sciatic nerve straight down the back of the limb. It serves the posterior, flexor compartment of the leg and, through its plantar branches, the sole of the foot.

In the popliteal fossa it runs vertically from the upper to the lower angle, the most superficial of the three main structures; the popliteal vein lies deep to it and the artery deeper still, and it crosses them from their lateral to their medial side. Here it gives off articular nerves to the knee: superior medial, middle and inferior medial genicular nerves. Its muscular branches go to both heads of gastrocnemius, plantaris, soleus and popliteus; the nerve to popliteus winds round the lower border of that muscle to enter its deep surface and also sends fibres to tibialis posterior, the tibiofibular joints, the tibia and the interosseous membrane. The medial sural cutaneous nerve also leaves in the fossa and joins the sural nerve lower down.

At the lower angle the nerve passes under the tendinous arch of soleus into the deep compartment of the calf, where it descends with the posterior tibial vessels on tibialis posterior and then on the back of the tibia. It supplies the deep calf muscles: tibialis posterior, flexor hallucis longus, flexor digitorum longus and the deep part of soleus. Behind the medial malleolus, halfway between it and the heel, it passes under the flexor retinaculum in the tarsal tunnel, gives medial calcaneal branches to the skin of the heel and a twig to the ankle joint, and divides into the medial and lateral plantar nerves.

Its deep course protects it, so injury is uncommon and usually follows direct trauma, a knee dislocation or a long period of compression. Loss above the calf muscles prevents plantar flexion and toe flexion, so the person cannot rise onto tiptoe, and weakens inversion, which survives only feebly through tibialis anterior. The ankle jerk is lost and the sole is numb. Compression in the tarsal tunnel, from swelling, a ganglion or overpronation, gives burning pain and tingling in the sole. The pulse of the posterior tibial artery beside the nerve behind the medial malleolus is a useful landmark for blocking it.

Course and supply

Arises from

The sciatic nerve's medial terminal division (L4-S3), at the apex of the popliteal fossa.

Ends in

Divides under the flexor retinaculum, where abductor hallucis arises, into the medial and lateral plantar nerves.

Supplies

Motor to the posterior leg muscles (plantar flexors of the ankle and long toe flexors) and through its plantar branches to the intrinsic muscles of the sole; sensory to the heel, the sole and, via the sural nerve, the lower calf and outer foot.