Tarsal tunnel

The tarsal tunnel is a fibro-osseous canal found in the medial aspect of the ankle.

Gross anatomy

Boundaries

• roof: flexor retinaculum
  • from the tip of the medial malleolus to the medial calcaneal process and plantar aponeurosis
• floor: medial surfaces of the tibia, talus and calcaneus ^{1, 2}

Contents

From anterior to posterior: 

• tibialis posterior tendon
• flexor digitorum longus tendon
• posterior tibial neurovascular bundle
  • posterior tibial artery and vein
  • tibial nerve: divides into the medial and lateral plantar nerves within the tunnel
• flexor hallucis longus tendon

A mnemonic to remember the order is Tom, Dick and Very Nervous Harry or Tom Doth Vex All Nervous Housemaids.

The tarsal tunnel is divided by fibrous septae joining the flexor retinaculum to the calcaneus, forming four separate compartments - one for each of the tendons and one for the neurovascular bundle ^1-3. 

It is continuous distally with plantar aponeurosis and proximally with the deep fascia of the leg. 

Variant anatomy

• 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 

Related pathology

• tarsal tunnel syndrome