The flexor retinaculum of the ankle is a strong obliquely oriented band in the crural fascia on the medial aspect of the ankle region. It attaches to the medial malleolus and then angles obliquely down and back to blend with the fascia over the dorsum of the heel. It passes superficial to grooves on the tibia and calcaneus to form fibro-osseous tunnels for the muscles of the deep posterior crural compartment and the posterior tibial vessels – the tibialis posterior, the flexor digitorum longus, the tibial artery and vein, and the flexor hallucis longus, from anterior to posterior respectively.

Retinaculum musculorum flexorum pedis