Tibialis posterior

The tibialis posterior (Latin: musculus tibialis posterior) is a long, relatively thin leg muscle. It is the deepest muscle of the posterior compartment of the leg. The tibialis posterior is situated most centrally of all leg muscles and is also the strongest among the posterior compartment muscles. The deep group of the posterior compartment of leg muscles also includes the popliteus, flexor digitorum longus and flexor hallucis longus muscles.

Origin

The tibialis posterior muscle originates from the upper half of the posterior surfaces of the tibia and fibula. Also, it arises from the interosseous membrane of the leg.

Insertion

The tibialis posterior inserts on the tuberosity of the navicular bone, cuboid bone, all cuneiform bones, bases of the second to fourth metatarsal bones and sustentaculum tali of the calcaneus.

Action

The tibialis posterior muscle provides foot plantarflexion at the talocrural (ankle) joint and foot inversion at the subtalar and midtarsal joints. It also supports the medial longitudinal arch of the foot.

Innervation

The tibialis posterior is innervated by the tibial nerve (L4 - L5) - a branch of the sciatic nerve.

Blood supply

The tibialis posterior receives arterial blood supply from the branches of the posterior tibial artery, mainly from the peroneal (fibular) artery.