Determination of safe zone for median nerve in carpal tunnel using anatomical landmarks

Carpal tunnel release, though common, carries a risk of iatrogenic median nerve injury, making it important to determine its safe zone within the tunnel using consistent palpable. In this study, 40 formalin-fixed upper limbs were dissected, and distances from the radial styloid process (RSP), palmaris longus tendon (PLT), and the medial-most point of the lower end of the ulna (LBU) to the median nerve (MN) were measured. The MN was consistently medial to the PLT and deep to the flexor retinaculum, with a mean RSP-MN distance of 28.48 mm, showing significant side differences (p = 0.001). A positive correlation between RSP-PLT and RSP-MN distances (r = 0.410, p = 0.016) confirmed the PLT as a useful landmark, while RSP and LBU served as reliable alternatives when PLT was absent. Thus, we show the clinical value of these anatomical landmarks in minimizing nerve injury during carpal tunnel procedures.