The tarsal tunnel is a narrow space on the inside ( medial aspect) of the ankle. There is a thick band (flexor retinaculum) that protects the structures within the tunnel. The structures include tendons, veins, the tibial nerve, and the posterior tibial artery. Tarsal tunnel syndrome is when the tibial nerve becomes entrapped along its course to the bottom of the foot. This can lead to burning pain in the heel along with tingling, and or numbness. Pain tends to worsen with prolonged stance and ambulation. Causes include flatfeet, abnormal structure or mass within the tunnel ( cyst or varicose veins), some systemic disease, and generalized inflammation or swelling.