Tibialis posterior muscle

The tibialis posterior is located in the deep posterior compartment of the leg. Its tendon runs through the flexor retinaculum (a.k.a. tarsal tunnel), making it the "Tom" in the Tom, Dick and very nervous Harry acronym for tendons passing through the tunnel.

Action: inversion and plantarflexion ankle

Innervation: tibial n.

Origin: tibia, fibula, and interosseous membrane

Insertion: navicular (tarsal) bone