A retinaculum is a band of thickened deep fascia around tendons that holds them in place. It is not part of any muscle and primarily functions to stabilize tendons. The term retinaculum is Neo-Latin, derived from the Latin verb retinere. Specific retinacula include:In the wrist: Flexor retinaculum of the hand Extensor retinaculum of the hand In the ankle: Flexor retinaculum of foot Superior extensor retinaculum of foot Inferior extensor retinaculum of foot Superior fibular retinaculum Inferior fibular retinaculum In the knee: Lateral retinaculum Medial patellar retinaculum