The tarsal tunnel is a fibro-osseous space located on the posteromedial aspect of the ankle.
It acts as a passageway for tendons, nerves and vessels to travel between the posterior leg and the foot.
In this article, we shall look at the anatomy of the tarsal tunnel – its borders, contents, and clinical relevance.
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Borders
The tarsal tunnel is formed by a bony floor and connective tissue roof.
The floor is a concave surface formed by the medial aspect of the tibia, talus and calcaneus.
It is converted into a tunnel by the flexor retinaculum, which spans obliquely between the medial malleolus and the medial tubercle of the calcaneus to form the roof. The flexor retinaculum is continuous with the deep fascia of the leg and foot.
Fig 1
The roof of the tarsal tunnel is formed by a flexor retinaculum extending from the medial malleolus to the medial tubercle of the calcaneus.
Contents
The tarsal tunnel acts as a passageway for tendons, nerves and vessels to travel between the posterior leg and the foot. Its contents (anterior to posterior) are:
- Tibialis posterior tendon
- Flexor digitorum longus tendon
- Posterior tibial artery and vein
- Tibial nerve
- Flexor hallucis longus tendon
- The mnemonic Tom, Dick and a Very Nervous Harry can be used to aid recall of these structures.
The tunnel is divided into four fibrous compartments – one containing the neurovascular structures and the other three containing the muscle tendons.
Clinical Relevance
Tarsal Tunnel Syndrome
Tarsal tunnel syndrome refers to entrapment and compression of the tibial nerve as it passes through the tarsal tunnel.
Patients may experience altered sensation in the sensory distribution of the tibial nerve – the sole of the foot.
The motor function of the nerve can also be affected in severe disease, causing weakness and wasting of the intrinsic foot muscles.
Management can be conservative or surgical:
- Conservative: Physiotherapy, NSAIDs, corticosteroid injections
- Surgical: Tarsal tunnel release (cutting through the flexor retinaculum to decompress the tunnel)
Fig 2
Tarsal tunnel syndrome is caused by compression of the tibial nerve as it passes through the tarsal tunnel