muscle | origin | insertion | innervation | action |
tibialis posterior | posterior, proximal tibia interosseous membrane medial surface of fibula | navicular tuberosity (principle) all 3 cuneiforms (plantar surface) bases of 2nd-4th metatarsals cuboid sustentaculum tali of calcaneus | tibial nerve, L5,S1 | stabilizes ankle inversion & adduction of foot prevents hyperpronation while in gait weak plantarflexion of ankle |
gastrocnemius | medial head: just above medial condyle of femur lateral head: just above lateral condyle of femur | calcaneus via lateral portion of calcaneal tendon | tibial nerve, S1,2 | plantarflex the ankle knee flexion (when not weight bearing) stabilizes ankle & knee when standing |
soleus | upper fibula soleal line of tibia | : calcaneus via medial portion of calcaneal tendon | tibial nerve, S1,2 | plantarflex the foot |
plantaris | above the lateral head of gastrocnemius on femur | calcaneus, medial to calcaneal tendon, or blending with the calcaneal tendon | tibial nerve, S1,2 | |
popliteus | lateral femoral condyle arcuate popliteal ligament lateral meniscus knee joint capsule | posterior tibial surface above the soleal line | tibial nerve, L5,S1 | insertion fixed: laterally rotates femur on tibia & unlocks knee origin fixed: medially rotates tibia on femur & unlocks knee |
flexor hallicus longus | posterior, inferior 2/3 of fibula interosseous membrane crural fascia & posterior intermuscular septum | plantar surface of distal phalanx of hallux | tibial nerve, L5,S1,2 | flexes big toe (hallux) weak plantarflexion of the foot weak inversion & adduction of foot |
flexor digitorum longus | posterior surface of tibia crural fascia | plantar surface of bases of the 2-5th distal phalanges | tibial nerve, L5,S1 | primarily flexes 2nd - 5th toes weak plantarflexor weak inversion & adduction of foot |