[TA] the disc that holds together the distal ends of the radius and ulna; it is attached by its apex to a depression between the styloid process and the distal surface of the head of the ulna, and by its base to the ridge separating the ulnar notch from the carpal surface of the radius. SYN: discus articularis radioulnaris distalis [TA], radioulnar disc, radioulnar articular disc, triangular cartilage, triangular disc of wrist, triquetrous cartilage (1).