- Posterior compartment of the lower leg
- General overview
- Divided into superficial and deep layers
- Innervated by the tibial nerves
- Supplied by the posterior tibial artery and peroneal (fibular) artery
- Functions include plantarflexion of the ankle, flexion of the toes, and inversion of the foot
- Superficial muscle group
- Gastrocnemius
- Origin: medial and lateral femoral condyles
- Insertion: calcaneus via the Achilles tendon
- Function: plantarflexion and knee flexion
- Innervation: tibial nerve
- Soleus
- Origin: posterior surface of tibia and fibula (soleal line)
- Insertion: calcaneus via the Achilles tendon
- Function: postural plantarflexion
- Innervation: tibial nerve
- Plantaris
- Origin: lateral supracondylar line of femur
- Insertion: calcaneus via a long thin tendon
- Function: weak plantarflexion, vestigial
- Innervation: tibial nerve
- Deep muscle group
- Popliteus
- Origin: lateral femoral condyle
- Insertion: posterior tibia above the soleal line
- Function: unlocks the knee (medial rotation of tibia)
- Innervation: tibial nerve
- Flexor hallucis longus (FHL)
- Origin: posterior fibula
- Insertion: distal phalanx of the great toe
- Function: flexes great toe, assists in plantarflexion
- Innervation: tibial nerve
- Flexor digitorum longus (FDL)
- Origin: posterior tibia
- Insertion: distal phalanges of lateral four toes
- Function: flexes toes, assists in plantarflexion
- Innervation: tibial nerve
- Tibialis posterior
- Origin: posterior tibia, fibula, and interosseous membrane
- Insertion: navicular, cuneiforms, cuboid, and bases of metatarsals 2–4
- Function: plantarflexion and inversion, supports medial arch
- Innervation: tibial nerve
- Neurovascular supply
- Tibial nerve
- Branch of the sciatic nerve
- Runs between superficial and deep layers
- Supplies all posterior compartment muscles
- Passes through the tarsal tunnel into the foot
- Posterior tibial artery
- Continuation of the tibioperoneal trunk
- Travels with the tibial nerve
- Gives off the peroneal artery and plantar branches
- Peroneal artery
- Branch of the posterior tibial artery
- Runs along the fibula
- Supplies the lateral compartment via perforating branches
- Tarsal tunnel
- Medial ankle passageway formed by the flexor retinaculum
- Contents from anterior to posterior:
- Tibialis posterior
- Flexor digitorum longus
- Posterior tibial artery
- Tibial nerve
- Flexor hallucis longus
- Mnemonic: Tom, Dick, And Nervous Harry
