Carpal tunnel syndrome: compression neuropathy of the median nerve within the carpal tunnel at the wrist; the commonest peripheral neuropathy of the upper limb.
Formation and Contents of the Carpal Tunnel
Carpal tunnel: formed by the anterior concavity of the carpus (carpal bones) posteriorly and the inelastic flexor retinaculum (transverse carpal ligament) anteriorly.
Contents: nine long flexor tendons (of flexor digitorum superficialis, flexor digitorum profundus and flexor pollicis longus) in their synovial sheaths, and the median nerve.
Aetiology
Causes of compression: tenosynovitis of flexor tendons (idiopathic, the commonest cause), myxedema (thyroxine deficiency), fluid retention in pregnancy, fracture dislocation of the lunate bone, and osteoarthritis of the wrist.