Overview
The tarsal tunnel is a fibro-osseous space located on the posteromedial aspect of the ankle, which acts as a passageway for neurovascular and tendinous structures to travel between the posterior compartment of the leg and foot.
Borders
- Roof: Flexor retinaculum (laciniate ligament)
- Floor: Medial surfaces of the tibia, talus and calcaneus
Contents
Medial to lateral (as well as anterior to posterior) order within the tunnel:
- Tibialis posterior tendon
- Flexor digitorum longus (FDL) tendon
- Posterior tibial artery and veins
- Tibial nerve – divides into the medial and lateral plantar nerves within the tunnel
- Flexor hallucis longus (FHL) tendon
The posterior tibial nerve passes between the FDL and FHL muscles before it bifurcates in the tarsal tunnel, forming the medial and lateral plantar nerves.
Normal Variants
- Flexor retinaculum absent or indistinguishable from crural fascia1
- Variable level of bifurcation of the tibial nerve either in, proximal or distal to the tarsal tunnel
- Variable level of bifurcation of the posterior tibial artery in the tarsal tunnel
- Lateral plantar nerve (LPN) and abductor digiti minimi (ADM) nerve share same origin
Mnemonic
The well-known mnemonic Tom, Dick And Very Very Nervous Harry follows the medial to lateral order of structures:
- Tom – Posterior tibialis tendon
- Dick – Flexor digitorum longus tendon
- And – Posterior tibial artery
- Very (x2) – Posterior tibial vein x 2
- Nervous – Tibial nerve
- Harry – Flexor hallucis longus tendon
Relevant Pathologies
- Tarsal tunnel syndrome
References