Tarsal Tunnel Syndrome
What Is the Tarsal Tunnel? 
The tarsal tunnel is a narrow space that lies on the inside of the ankle next to the ankle bones. The tunnel is covered with a thick ligament (the flexor retinaculum) that protects and maintains the structures contained within the tunnel-arteries, veins, tendons and nerves. One of these structures is the posterior tibial nerve, which is the focus of tarsal tunnel syndrome.

What Is Tarsal Tunnel Syndrome?
Tarsal tunnel syndrome is a compression, or squeezing, on the posterior tibial nerve that produces symptoms anywhere along the path of the nerve running from the inside of the ankle into the foot.

Tarsal tunnel syndrome is similar to carpal tunnel syndrome, which occurs in the wrist. Both disorders arise from the compression of a nerve in a confined space.