The Tibialis Posterior is located in the deep compartment of the lower leg, and is a key stabilising muscle, supporting the medial arch of the foot.
Proximal postero-lateral aspect of the tibia.
Proximal postero-medial 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.
The major insertion is onto the navicula and the plantar slip attatches to the medial cuniform
Tibial Nerve (L4-S3)
To plantarflex and invert the ankle. It also plays an important role in stabilising the medial longitudinal arch. Tibialis posterior dysfunction can lead to flat feet in adults.| 
Resisted Muscle Test:
Strengthening exercises for Tibialis Posterior:| 
- Drake RL, Vogl W, Mitchell AWM. Gray's Anatomy for Students. 2nd Ed. Philadelphia: Churchill Livingstone Elsevier, 2010.
- nabil ebraheim. Anatomy Of The Tibialis Posterior Muscle - Everything You Need To Know - Dr. Nabil Ebraheim. Available from: https://www.youtube.com/watch?v=9N_eR8Pojuw [last accessed: 25/6/18]
- Sheena Livingstone. Tibialis Posterior Muscle Test. Available from: http://www.youtube.com/watch?v=7cEJD-9aBTk [last accessed 25/6/18]
- PolkStatePTA. Tibialis Posterior. Available from: http://www.youtube.com/watch?v=f-vVv59NNBI [last accessed 25/6/18]
- Physiotutors. Tibialis Posterior Strengthening | Flat Feet Exercise. Available from: https://www.youtube.com/watch?v=XBvfk3zwiiE [last accessed: 25/6/18]