Figure 1. Carpal tunnel. Longitudinal 5-12-MHz US scan obtained in an asymptomatic 42-year-old man shows the hypoechoic median nerve (MN), which lies just underneath the flexor retinaculum (arrowheads) and superficial to the hyperechoic flexor tendons (FT). Note that the nerve angles away from the transducer on entering the tunnel. L = lunate, R = distal radius.