Tarsal tunnel anatomy

The tarsal tunnel syndrome is caused by entrapment of the posterior tibial nerve beneath the flexor retinaculum on the medial side of the ankle. Entrapment may also include the two branches, the medial and lateral plantar nerves. Note that the bifurcation of the tibial nerve, which is depicted occurring proximal to the retinaculum in the diagram above, can occur more distally in the region of the retinaculum.