Basic Foot and Ankle Anatomy - Neural and Vascular

Original Editor - Ewa Jaraczewska

Top Contributors - Ewa Jaraczewska, Wanda van Niekerk, Jess Bell, Kim Jackson, Lucinda hampton and Olajumoke Ogunleye

Description

Identification of compression syndromes requires a very good understanding of the anatomy of the nerves and vessels of the foot and ankle. Morton's neuroma, Baxter neuropathy or jogger's heel (Plantar Fasciitis) syndromes are common pathologies requiring a physiotherapist's intervention.

Neural

Tibial nerve

Ankle and Foot

Tibial Nerve

The Tibial nerve originates at L5, S1 and S2 levels together with the common peroneal (fibular ) nerve.

Distribution: popliteal fossa→between two heads of the gastrocnemius→medial border of the Achilles tendon→inferior and posterior to the medial malleolus→separates into calcaneal nerve brunches and medial and lateral plantar nerve→sole of the foot.

• Motor fibres: gastrocnemius, soleus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus.

• Sensory fibres: occasionally supplies the area typically innervated by the deep peroneal nerve.

Plantar Nerve

The plantar nerve originates from the tibial nerve at the medial malleolus. The nerve divides into two branches: medial and lateral. It provides motor and sensory innervation to the foot muscles.

• Medial plantar nerve
  • Motor fibres: abductor hallucis, flexor digitorum brevis, and flexor hallucis brevis muscles.
  • Sensory fibres: sole innervation, 1st, 2nd and 3rd toes, often 4th toe.

• Lateral plantar nerve
  • Motor fibres: abductor and flexor digiti minimi, the adductor hallucis, and the interossei muscles.
  • Sensory fibres: sole innervation, 5th toe, occasionally 4th toe.

Calcaneal Nerve

Nerves of the foot

The calcaneal nerve is a terminal branch of the tibial nerve.

• Medial calcaneal nerve
  • Motor fibres: abductor hallucis
  • Sensory fibres: medial border of the heel.

• Inferior calcaneal nerve (Baxter's nerve): originates from lateral plantar nerve (30%) and medial calcaneal nerve (70%).
  • Motor fibres: flexor digitorum brevis, quadratus plantae, abductor digiti minimi.
  • Sensory fibres: plantar ligament, calcaneal periosteum.

Common Fibular (Peroneal) Nerve

Fibular nerve

The common fibular nerve originates at nerve roots L4, S1, and S2 together with the tibialis nerve.

Distribution: popliteal fossa→medial border of the biceps femoris→lateral head of the gastrocnemius→neck of the fibula→between the attachments of the fibularis longus muscle→divides into superficial and deep fibular nerves.

• Superficial
  • Motor fibres: fibularis longus and brevis
  • Sensory fibres: skin of the anterolateral leg, and dorsum of the foot (except the skin between the first and second toes).

• Deep: occasionally becomes the pure sensory nerve
  • Motor fibres: tibialis anterior, extensor digitorum longus, extensor hallucis longus, extensor digitorum brevis (rarely innervated by the tibial nerve).
  • Sensory fibres: lateral part of the ankle and foot regions, the skin between the first and second toes.

Sural Nerve

The Sural nerve originates from the tibial nerve and cutaneous branches of the common fibular nerve. It is divided into the sural communication nerve and lateral sural cutaneous nerve.

• Sensory fibres: posterior aspect of the distal leg and lateral aspect of the foot.

Vascular

Ankle and Foot

Popliteal Artery

Lower limb arteries

• Distribution: femoral artery→popliteal fossa→between the gastrocnemius and popliteal muscles in the posterior compartment of the leg→between the two heads of the gastrocnemius→divides into anterior and posterior tibial arteries.
• Supply: superficial posterior compartment including gastrocnemius, soleus and plantaris muscles.

Tibial Artery

Anterior tibial artery

Anatomic view of the anterolateral part of the ankle showing the relationship between the anterior tibiofibular ligament and the perforating branch of the peroneal artery (arteries are filled with black latex). 1 Anterior tibiofibular ligament; 2 distal fascicle of the anterior tibiofibular ligament; 3 anterior tubercle of the tibia; 4perforating branch of peroneal artery; 5 triangular region of the talus; 6 anterior malleolar artery;

• Distribution: popliteal fossa→lower border of the popliteus muscle→posterior compartment of the leg→between heads of the posterior tibialis muscle→proximal part of the interosseous membrane→medial to the fibular neck→anterior compartment of the leg→anterior aspect of the interosseous membrane →anterior surface of the tibia→dorsalis pedis artery
• Supply: proximal tibiofibular joint, knee joint, ankle joint, muscles and skin of the anterior compartment of the leg.

Posterior tibial artery

• Distribution: terminal branch of the popliteal artery at the lower margin of the popliteus muscle→posterior compartment of the leg→inferior to the medial malleolus→tubercle of calcaneus→lateral and medial plantar arteries.
• Supply: soleus muscle, popliteus, flexor hallucis longus, flexor digitorum longus and tibialis posterior.

Fibular (Peroneal) Artery

• Distribution: posterior tibial artery, distal to the popliteus muscle→medial side of the fibula→inferior tibiofibular syndesmosis→calcaneal branches.
• Supply: popliteus, soleus, tibialis posterior, and flexor hallucis longus muscles.

Arteries of the foot

Plantar Artery

• Medial and lateral plantar arteries form a plantar arch extending from the 1st to the 5th metatarsal. It joins a deep plantar branch of the dorsalis pedis.
• The medial plantar artery supplies abductor hallucis muscle and flexor digitorum brevis muscle.
• The lateral plantar artery supplies plantar aponeurosis between flexor digitorum brevis and abductor digiti minimi muscles.

Sural Artery

• The sural artery originates from each side of the popliteal artery. It has two branches: lateral and medial.
• Supply: gastrocnemius muscle, soleus muscle and plantaris muscle.

Clinical relevance

1. Inferior calcaneal nerve entrapment (Baxter neuropathy) presents with heel pain and paraesthesia with the abductor digiti minimi muscle weakness.
2. When the common fibular nerve is damaged, the patient may not be able to dorsiflex and evert the foot and extend the digits.
3. Sural artery flap is used for the reconstruction of soft tissue defects around the lower third of the leg, dorsum of the foot, malleoli and hindfoot.

Resources

Anatomy of the Ankle Ligaments: A Pictorial Essay - In this pictorial essay, the ligaments around the ankle are grouped, depending on their anatomic orientation, and each of the ankle ligaments is discussed in detail.