Tibial Nerve Anatomy Animation _ Origin, course, Branches, Tarsal tunnel syndrome _ USMLE Step 1 480

Tibial Nerve Overview

  • Origin: Derived from the ventral divisions of the ventral rami of L4 to S3 spinal nerves.

  • Relationship: Component of the sciatic nerve.

Anatomy

  • Location: Arises as a terminal branch of the sciatic nerve at the back of the thigh, at the junction of the upper 2 thirds and lower 1 third of the thigh.

  • Pathway: Enters the popliteal fossa.

    • Position in Fossa: Lies lateral to the popliteal vessels, becomes superficial at the knee crossing to the medial side of the artery.

    • Branches: Gives rise to the sural nerve in the popliteal fossa.

Sural Nerve

  • Anatomy: Joined by a sural communicating nerve from the common peroneal nerve.

  • Function: Supplies skin on:

    • Lower part of the back of the leg

    • Lateral border and adjoining part of the dorsum of the foot

    • Lateral side of the little toe

Passage through the Leg

  • Compartment Entry: Enters the posterior compartment of the leg by passing deep to the tendon arch of the soleus.

  • Position Relative to Artery: Initially medial to the posterior tibial artery, then crosses from medial to lateral, eventually running alongside the lateral side of the artery.

  • Branches: Gives off medial calcaneal branches just above the flexor retinaculum.

  • Termination: Divides into medial and lateral plantar nerves deep to the flexor retinaculum.

Innervation

Motor Innervation

  • Muscles Innervated:

    • In the popliteal fossa: plantaris, gastrocnemius, popliteus

    • In the leg: soleus, flexor digitorum longus, tibialis posterior, flexor hallucis longus

Sensory Innervation

  • Branches:

    • Medial Calcaneal Branches: Pierces flexor retinaculum to supply skin of the heel.

    • Sural Nerve: Supplies skin on the lower lateral part of the leg and foot, including the little toe.

Clinical Correlations

Tibial Nerve Injury

  • Causes: Commonly injured by lacerations in the popliteal fossa or posterior dislocation of the knee joint.

Symptoms of Injury

Motor Symptoms

  • Foot Position: Dorsiflexed and averted due to paralysis of posterior leg muscles.

  • Loss of Prominence: Of the calf and tendocalcaneus due to paralysis of gastrocnemius and soleus.

  • Plantarflexion Loss: Due to paralysis of ankle flexors, causing inability to stand on toes.

Sensory Symptoms

  • Loss of Sensation: In the sole and plantar aspects of the toes, including dorsal aspects of their distal phalanges.

Tarsal Tunnel Syndrome

  • Definition: Compression of the tibial nerve in the osseofibrous tunnel under the flexor retinaculum of the ankle.

  • Symptoms: Pain and paresthesia in the sole of the foot, often worsens at night.

Conclusion

  • The tibial nerve is essential for both motor and sensory functions in the leg and foot, and its injuries can lead to significant impairments.