Tibialis Posterior: The tibialis posterior is central of all the leg muscles and is placed in the deep posterior compartment of the leg.It is the fundamental stabilizing muscle of the lower leg.
Origin: Proximal two-thirds of the posterior surfaces of the tibia and the fibula and the interosseous membrane.
Insertion: The tibialis posterior muscle separates into two sheets later crossing inferior to the plantar calcaneonavicular ligament; the superficial slip inserts on the tuberosity of the navicular and sometimes medial cuneiform bone; deeper slip distributes again into slips inserting on plantar surfaces of metatarsals 2 – 4 and second cuneiform bone.
Function: Key invertor of the foot; further adducts foot, plantar flexes ankle joint, and assists to supinate the foot.
Nerve Supply: Tibial nerve (L4, L5).