Posterior Fascial Compartment of Leg

• Gastrocnemius

  Origin: Lateral head from lateral condyle of femur and medial head from above medial condyle

  Insertion: Via tendo calcaneus into posterior surface of calcaneum

  Nerve: Tibial nerve

  Action: Plantarflexes foot at ankle joint; flexes knee joint
• Plantaris

  Origin: Lateral supracondylar ridge of femur

  Insertion: Posterior surface of calcaneum

  Nerve: Tibial nerve

  Action: Plantarflexes foot at ankle joint; flexes knee joint
• Soleus

  Origin: Shafts of tibia and fibula

  Insertion: Via tendo calcaneum into posterior surface of calcaneum

  Nerve: Tibial nerve

  Action: Together with gastrocnemius and plantaris is powerful plantarflexor of ankle joint; provides main propulsive force in walking and running
• Popliteus

  Origin: Lateral surface of lateral condyle of femur

  Insertion: Posterior surface of shaft of tibia above soleal line

  Nerve: Tibial nerve

  Action: Flexes leg at knee joint; unlocks knee joint by lateral rotation of femur on tibia and slackens ligaments of joint
• Flexor digitorum longus

  Origin: Posterior surface of shaft of tibia

  Insertion: Bases of distal phalanges of lateral four toes

  Nerve: Tibial nerve

  Action: Flexes distal phalanges of lateral four toes; plantarflexes foot at ankle joint; supports medial and lateral longitudinal arches of foot
• Flexor hallucis longus

  Origin: Posterior surface of shaft of fibula

  Insertion: Base of distal phalanx of big toe

  Nerve: Tibial nerve

  Action: Flexes distal phalanx of big toe; plantarflexes foot at ankle joint; supports medial longitudinal arch of foot
• Tibialis posterior

  Origin: Posterior surface of shafts of tibia and fibula and interosseous membrane

  Insertion: Tuberosity of navicular bone and other neighboring bones

  Nerve: Tibial nerve

  Action: Plantarflexes foot at ankle joint; inverts foot at subtalar and transverse tarsal joints; supports medial longitudinal arch of foot