Muscles of the leg (Posterior view) (English)

The posterior compartment of the leg can be divided into superficial and deep parts by the transverse intermuscular septum. The superficial muscles of the posterior leg include the gastrocnemius, soleus and plantaris. The large gastrocnemius and soleus collectively form the triceps surae muscle which is a powerful plantar flexor of the foot at the ankle joint. A large shared common tendon, the calcaneal tendon (a.k.a. Achilles tendon), extends from the muscle bellies of the triceps surae muscle to insert onto the posterior aspect of the calcaneus. The plantaris muscle has a short belly and a long tendon which extends along the posterior leg to also insert onto the posterior calcaneus. This muscle contributes to proprioception during plantarflexion of the ankle joint. The deep muscles of the posterior leg comprise four muscles: the popliteus, flexor digitorum longus, flexor hallucis longus, and tibialis posterior. The short popliteus muscle acts on the knee joint, while the rest of the deep muscles of the posterior leg contribute to plantarflexion of the foot at the ankle joint, in addition to other individual functions. The flexor digitorum longus and flexor hallucis longus muscles also contribute to flexion of the toes at the metatarsophalangeal and interphalangeal joints.