Tibialis Posterior

 Anatomy and Function

Origion	Proximal posterolateral aspect of the tibia. Proxmial posteromedial aspect of the fibula and the interosseous membrane.
Mid portion	Situated in the deep posterior compartment of the lower leg and runs proximal to the medial malleoli where it is secured by the flexor retinaculum.
Insertion	The major insertion is onto the navicula and the plantar slip attatches to the medial cuniform
Innervation	Tibial Nerve (L4-S3)
Function	To plantarflex and invert the ankle. It also plays an important role in stabilising the medial longitudinal arch.