Which band of tissue forms the roof over the carpal tunnel?

• A. Flexor retinaculum
• B. Extensor retinaculum
• C. Palmar aponeurosis
• D. Annular ligament

Answer: (A)

The roof of the carpal tunnel is formed by the flexor retinaculum, a thick transverse band of deep fascia that spans the carpal bones on the palm side. This sturdy ligament converts the carpal bones into a tunnel, guiding the flexor tendons and the median nerve as they pass into the hand. The extensor retinaculum runs along the back of the wrist, covering the extensor tendons, so it isn’t the roof of the carpal tunnel. The palmar aponeurosis sits in the palm itself, and the annular ligaments are associated with finger pulleys, not the carpal tunnel boundary. Understanding this boundary helps explain why compression under the flexor retinaculum can lead to carpal tunnel syndrome.