Near the ankle, the tendon of the tibialis posterior is crossed superficially by the tendon of the flexor digitorum longus muscle and lies medial to this tendon in the groove on the posterior surface of the medial malleolus. The tendon curves forward under the medial malleolus and enters the medial side of the foot. It wraps around the medial margin of the foot to attach to the plantar surfaces of the medial tarsal bones, mainly to the tuberosity of the navicular and to the adjacent region of the medial cuneiform.