A retinaculum (pl.: retinacula) is a band of thickened deep fascia around tendons that holds them in place.^[1] It is not part of any muscle and primarily functions to stabilize tendons. The term retinaculum is Neo-Latin,^[2] derived from the Latin verb retinere (to retain). 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