Tibial Nerve Anatomy

The tibial nerve is the workhorse of the posterior leg and foot: it plantarflexes the ankle, flexes the toes, inverts the foot and gives the sole its sensation — so it is the nerve you assess in a knee dislocation, a posterior-leg or popliteal injury, and any patient with sole symptoms. Its exam value clusters at two sites: the popliteal fossa (where it is the most superficial of the bundle and at risk with the popliteal artery in knee dislocation) and the tarsal tunnel behind the medial malleolus (where it and its plantar branches are compressed or entrapped). Hold three ideas together — the course (sciatic → popliteal fossa → deep posterior compartment → tarsal tunnel → plantar nerves), the deficit (loss of plantarflexion/toe flexion and an insensate sole), and the entrapments (tarsal tunnel syndrome, Baxter's nerve, jogger's foot).

• Plantarflexion (gastrocnemius-soleus - "tiptoe"), inversion (tibialis posterior) and toe flexion (FDL/FHL) all depend on the tibial nerve.
• Sensory: the sole of the foot (medial plantar - medial sole and medial 3.5 toes; lateral plantar - lateral sole and lateral 1.5 toes), the heel (medial calcaneal), and a contribution to the sural nerve (posterolateral leg/lateral foot).

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Beyond tarsal tunnel syndrome, three practical points round out the foot-and-ankle examiner's expectations.

• Posterior tibial nerve block. The tibial nerve is blocked behind the medial malleolus, just posterior to the posterior tibial artery, as part of an ankle block for forefoot and sole surgery — it is the component that anaesthetises the sole. Knowing its position relative to the artery (nerve posterior to the pulse) is the practical landmark.
• Jogger's foot (medial plantar nerve entrapment). The medial plantar nerve can be entrapped at the knot of Henry (where FDL and FHL tendons cross) or under the abductor hallucis, classically in runners with a valgus/pronated foot — producing medial arch/sole burning and altered sensation of the medial sole and medial toes.
• Baxter's nerve revisited. The first branch of the lateral plantar nerve (Baxter's / inferior calcaneal nerve) is entrapped between abductor hallucis and quadratus plantae and is a frequently-missed cause of chronic plantar heel pain that mimics plantar fasciitis — suspect it when heel pain is refractory or associated with abductor digiti minimi wasting.
• Proximal entrapment at the soleal sling. The tarsal tunnel is the distal entrapment, but the tibial nerve can also be compressed proximally where it passes deep to the tendinous arch of soleus (the "soleal sling") as it enters the deep posterior compartment — proximal/high tibial neuropathy. This produces calf pain with plantar paraesthesia and a Tinel sign high in the popliteal/proximal-calf region rather than behind the medial malleolus, and is a recognised (often exertional) cause of posterior-leg and sole symptoms that a medial-ankle examination will miss — so localise the level of the Tinel sign and consider the soleal sling when tarsal-tunnel signs are absent.

Global Practice Picture

Tibial nerve anatomy underpins management of tarsal tunnel syndrome, plantar heel pain (Baxter's nerve), posterior leg compartment and popliteal injuries, and the assessment of the insensate foot. The internationally consistent principles are: know the tarsal tunnel contents and plantar division, diagnose tarsal tunnel syndrome clinically with electrodiagnostic/imaging support, and treat the underlying cause.

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