There are three radioulnar joints. The proximal joint involves the convex head of the radius rotating with the stable concave ulna. The middle joint involves the radial and ulnar shafts stabilized with an interosseous membrane - it is not palpable from the bodyís surface. The distal joint involves the concave distal radius articulating with the convex distal ulna.
With the patient relaxed, gently wrap the fingers and thumb around the head of the radius. Palpate the rotating radial head as it articulates with the stationary proximal ulna as the patient is guided to pronate and supinate the forearm.