Peroneal & Tibial Nerves - Essentials

Peroneal & Tibial Nerves - Essentials

Peroneal and tibial nerves anatomy and innervation

Relevant anatomy

• Femur
• Fibula
• Tibia
• Ankle
  • The medial malleolus, medially.
  • The lateral malleolus, laterally.
• Sciatic nerve (L4–S3)
  • Passes down the posterior thigh and proximal to the popliteal fossa, it unbundles into the common peroneal nerve and tibial nerve.

Peroneal and Tibial Nerves: Key Anatomy & Innervation

Common peroneal nerve

• Passes inferolaterally through the popliteal fossa.
• Wraps around the fibular neck and then splits into the deep peroneal nerve and superficial peroneal nerve.

Deep peroneal nerve

• Innervates the muscles of the anterior leg and dorsum of the foot.
  • Tibialis anterior overlies it.
  • Extensor digitorum longus (EDL) lies underneath it.

Superficial peroneal nerve

• Innervates the muscles of the lateral leg.
  • Peroneus longus overlies the superficial peroneal nerve.

Tibial nerve

• Continues straight down the posterior leg.
• Innervates the muscles of the posterior leg and plantar foot.
  • Tibialis posterior lies underneath it.

Key compression sites

• Peroneal nerve
  • The fibular neck: the continuation of the head of the fibula (the top of the lateral leg bone).
  • Causes foot drop.

• Tibial nerve
  • The popliteal fossa: the depression behind the knee.
  • The tarsal tunnel, which is the medial entry zone of the tibial nerve through the ankle into the foot.
  • Causes difficult raising up on the ball of the foot.
  • The medial malleolus and medial calcaneus form the superior and inferior boundaries of the tarsal tunnel and the flexor retinaculum forms its roof.

Sural sensory nerve

• Passes posterior to the lateral malleolus of the fibula.
• Sensory branches of the tibial and peroneal nerves merge to form the sural sensory cutaneous nerve, which is a commonly tested nerve in electrodiagnostics and can be palpated along the lateral malleolus.
• Most often compressed at the lateral malleolus.