Tibial nerve lesions

The tibial nerve provides motor innervation to the muscles of the posterior compartment of the leg (superficial and deep). It provides sensory innervation to the posterior aspect of the leg (via the sural nerve) and the sole of the foot.

Injury typically results in:

• Loss of plantar flexion of the foot and toes
• Weakened inversion of the foot
• Sensory loss over the posterior leg and sole of the foot

The tibial nerve is generally well protected by surrounding muscle but is most vulnerable in the popliteal fossa.

Anatomy

Course of the tibial nerve

• Arises from the sciatic nerve in the lower third of the thigh
• Derived from anterior divisions of L4–S3
• Travels through the popliteal fossa:
  • Initially lateral to the popliteal artery
  • Passes posterior to it at the knee
  • Then medial to it at the level of the popliteus
• Vein lies between nerve and artery throughout
• Continues into the posterior leg deep to soleus
• Descends lateral to the posterior tibial artery
• At the ankle, passes posterior to the medial malleolus under the flexor retinaculum

Structures deep to the flexor retinaculum (anterior to posterior):

Mnemonic: Tom, Dick And Very Naughty Harry

• Tibialis posterior
• Flexor digitorum longus
• Posterior tibial artery
• Venae comitantes
• Tibial nerve
• Flexor hallucis longus

Tibial nerve innervations

In the popliteal fossa

Motor:

• Soleus
• Gastrocnemius
• Popliteus
• Plantaris

Sensory:

• Knee joint
• Medial sural cutaneous nerve → joins peroneal communicating nerve → sural nerve → supplies lateral foot to the 5th toe

Below the popliteal fossa

Motor:

• Flexor digitorum longus
• Flexor hallucis longus
• Tibialis posterior

Sensory:

• Ankle joint
• Medial calcaneal nerve → medial heel and plantar surface

Terminal branches at ankle

Medial plantar nerve

Motor:

• Abductor hallucis
• Flexor digitorum brevis
• Flexor hallucis brevis
• 1st lumbrical

Sensory:

• Medial sole and medial 3½ toes (including nail beds)

Lateral plantar nerve

• Runs with lateral plantar artery
• Divides at 5th metatarsal into superficial and deep branches

Main trunk motor:

• Quadratus plantae
• Abductor digiti minimi

Main trunk sensory:

• Lateral sole

Superficial branch:

• Motor: flexor digiti minimi brevis, 4th interosseous
• Sensory: lateral 1½ toes (including nail beds)

Deep branch:

• Adductor hallucis
• 2nd–4th lumbricals
• 1st–3rd interossei

Pathology

Causes of tibial nerve lesions

1. Trauma
   • Direct trauma to popliteal fossa or medial malleolus
   • Knee dislocations
2. Neuropraxias
   • Posterior leg compartment syndrome
3. Mass lesions
   • Tumours
   • Abscesses
4. Neuropathies
   • Mononeuropathies from systemic disease (rarely affects tibial nerve)

Clinical assessment

Investigations

Blood tests

• FBC
• U&Es / glucose
• CRP
• ESR
• Others (e.g. lead levels)

Imaging

• CT / MRI: to delineate compressive lesions or visualise the nerve

Nerve conduction studies

• Confirm diagnosis
• Exclude generalised disease
• Determine prognosis

Management

1. Treat underlying cause
2. Neuropraxia
   • Fasciotomy for compartment syndrome
3. Occupational therapy
   • Splints and aids
4. Physiotherapy
   • Recovery and prevention of complications

Disposition

Depends on:

• Cause of lesion
• Symptom severity
• Acute vs chronic presentation

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Appendix 2

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References

Publications

• Brazis PW, Masdeu JC, Biller J. Localization in Clinical Neurology. 8e 2021
• Fuller G. Neurological Examination Made Easy. 6e 2019
• O’Brien M. Aids to the Examination of the Peripheral Nervous System. 6e 2023

FOAMed

• Coni R. Neuro 101: Peripheral Nervous System. LITFL
• Nickson C. Myotomes and Differentiating Nerve Lesions. LITFL