Explanation:
The transverse carpal ligament forms the roof of the carpal tunnel and spans from the scaphoid tubercle and trapezium laterally to the pisiform and hook of hamate medially. Beneath this ligament pass the median nerve and nine flexor tendons. Thickening or increased pressure within the tunnel can compress the median nerve, resulting in carpal tunnel syndrome. Surgical decompression involves division of the transverse carpal ligament, which relieves pressure within the tunnel and improves nerve function. Reference: Phalen GS, 'The carpal-tunnel syndrome: clinical evaluation of 598 hands', Clinical Orthopaedics and Related Research (1972).