Muscles of the Leg Anterior Compartment Tibialis anterior

Muscles of the Leg

Anterior Compartment • • Tibialis anterior muscle Extensor hallucis longus muscle Extensor digitorum longus muscle Fibularis (peroneus) tertius muscle • All supplied by the deep fibular nerve

Tibialis anterior muscle

• L 4, L 5 • DF • Inversion

Extensor Hallucis Longus muscle

• L 5, S 1 • Extends big toe • Assists dorsiflexion of ankle • Weak ankle inversion

Extensor Digitorum Longus muscle

• L 5, S 1 • Extends lateral four toes • Ankle dorsiflexion • Everts the foot at the subtalar joints

Fibularis tertius muscle • Not seen in all people • L 5, s 1 • Ankle eversion at subtalar joint • DF of foot at ankle joint

Lateral Compartment Muscles • Fibularis longus muscle • Fibularis brevis muscle • Both innervated by the superficial fibular nerve, L 5, S 1, • Both have actions of: – Plantar flexion of ankle – Eversion of ankle

Fibularis longus muscle • Common fibular nerve • Superficial fibular nerve

Fibularis brevis muscle

Posterior Leg Muscles • Which nerve? • Superficial posterior muscles – Gastrocnemius muscle – Soleus muscle – Plantaris muscle • Deep posterior muscles – – Popliteus muscle Flexor digitorum longus muscle Flexor hallucis longus muscle Tibialis posterior muscle

Gastrocnemius muscle

• S 1, S 2 • PF ankle • Flexes leg at knee • Inverts the foot at the subtalar joints

Soleus muscle

• S 1, S 2 • PF ankle • Postural muscle • Inverts the foot at the subtalar joints

Plantaris muscle

• S 1, S 2 • Weak PF • Weak knee flexion • Inverts the foot at the subtalar joints

Popliteus muscle

• L 4, L 5, S 1 • Flexes knee • Medially rotates the leg at the knee in open chain • Laterally rotates the femur at the knee in closed chain

Flexor digitorum longus muscle

• L 5, S 1, S 2 • Flexes lateral 4 toes – Primarily distal phalanx • PF ankle • Assists inversion of the foot at the subtalar joints

Flexor hallucis longus muscle

• L 5, S 1, S 2 • Flexes distal phalanx of big toe • PF ankle • Inversion of foot at subtalar joints

• Note relationship of FDL and FHL

Tibialis posterior muscle

• L 4, L 5 • PF • Inverts foot • Supports arch of foot

Muscle Hints • Tibialis *** muscles – Common action: – Common spinal level: • Fibularis *** muscle – Common action:

• All Anterior and Lateral compartment muscles EXCEPT for Tibialis ant. muscle – Common Spinal level: • Superficial Post. Comp. muscles – Common spinal level:

• Toe flexor muscles – Common spinal level – Common actions: • Popliteus muscle – Spinal levels: