sentences:  The carpal bones that make up the wrist form an arch which is convex on the dorsal side of the hand and concave on the palmar side.The groove on the palmar side, the "sulcus carpi", is covered by the flexor retinaculum, a sheath of tough connective tissue, thus forming the carpal tunnel.On the side of the radius, the flexor retinaculum is attached to the scaphoid bone, more precisely its tubercle, as well as the ridge of trapezium.