Carpal tunnel

The carpal tunnel is formed posteriorly and laterally by the bones (carpals) of the wrist, and anteriorly is completed by a thick band of connective tissue, the transverse carpal ligament (= flexor retinaculum).  9 muscle tendons and 1 nerve pass through the tunnel on their way from the forearm into the hand; 4 tendons of flexor digitorum superficialis, 4 tendons of flexor digitorum profundus, tendon of the flexor pollicis longus, and the median n.  The tunnel is inelastic, so any inflammation within the carpal tunnel compresses the median n. and gives rise to the symptoms of carpal tunnel syndrome.