What is flexor retinaculum of the foot?

The flexor retinaculum of the foot, also known as the medial ankle retinaculum or the laciniate ligament, is a fibrous band that connects the tibia and the fibula to the bones of the foot. It is located on the medial (inner) side of the ankle and runs from the medial malleolus (the bony prominence on the inside of the ankle) to the calcaneus bone (heel bone).

The flexor retinaculum forms a tunnel or canal (the tarsal tunnel) for several tendons, nerves, and blood vessels that pass from the leg into the foot. These structures include the posterior tibial nerve, the posterior tibial artery, the posterior tibial vein, and several tendons of the flexor muscles (such as the flexor digitorum longus, the flexor hallucis longus, and the tibialis posterior).

The flexor retinaculum helps to hold these structures in place, prevent them from shifting or rubbing against each other, and provide support to the arch of the foot. However, if the flexor retinaculum becomes tight or inflamed, it can compress or irritate the structures within the tarsal tunnel, causing pain, numbness, tingling, weakness, or other symptoms in the foot and ankle. This condition is known as tarsal tunnel syndrome and often requires medical treatment.