Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

Leg Compartments

• The leg contains four compartments: anterior, lateral, superficial posterior, and deep posterior.
• The extensor digitorum longus lies in the anterior compartment of the leg.

Muscles of the Anterior Compartment

• Tibialis anterior.
• Extensor hallucis longus.
• Extensor digitorum longus.
• Peroneus tertius.
• All muscles in the anterior compartment are supplied by the deep peroneal (deep fibular) nerve.

Origin

• Lateral condyle of the tibia.
• Upper three-fourths of the anterior surface of the fibula.
• Interosseous membrane.

Insertion

• Divides into four tendons.
• Inserts into the middle and distal phalanges of the lateral four toes.

Course of Tendons

• The tendon forms above the superior extensor retinaculum.
• Passes under the superior and inferior extensor retinacula.
• Divides into four tendons distal to the retinaculum.

Function

• Dorsiflexion of the ankle.
• Extension of the lateral four toes.

Innervation

• Deep peroneal (deep fibular) nerve.

Important Sensory Landmark

• Injury to the deep peroneal nerve causes numbness in the first web space of the foot.

Relation to the Anterior Tibial Artery

• Anterior tibial artery enters anterior compartment through the interosseous membrane.
• Proximally it runs between tibialis anterior (medial) and extensor digitorum longus (lateral).
• Distally the artery runs between extensor hallucis longus (medial) and extensor digitorum longus (lateral).

Arrangement of Structures at the Anterior Ankle

• Mnemonic: ‘Tom Has A Very Nice Dog’.
• T – Tibialis anterior.
• H – Extensor hallucis longus.
• A – Anterior tibial artery.
• V – Vein.
• N – Deep peroneal nerve.
• D – Extensor digitorum longus.