Tibialis Posterior
Origin = Upper two-thirds of the tibia, posterior surface; upper two-thirds of the fibula, medial surface; and adjacent portions of th einterossius membrane.
Insertion = Navicular, calcaneus, cuboid, the three cuneiforms, and the bases of the second third and fourth metatarsals.
Action = Plantar flexion of the ankle joint; inversion of the midtarsal joint.