Originally Posted by julian
may I ask you a favor.
Could you provide a verbal definition of radial deviation?
The picture above does NOT say whether it is a planar movement or NOT.
If you can address this issue it would nice as well
a possible definition of ulnar deviation from Wikipedia below
Ulnar deviation is also a physiological movement of the wrist, where the hand including the fingers move towards the ulna. Ulnar deviation is a disorder in which flexion by ulnar nerve innervated muscles is intact while flexion on the median nerve side is not.
Radial deviation is movement of the wrist, where the hand moves towards the radius (bone of the forehand).
BTW, the question about planar motion is very difficult. Brian Gordon wrote somewhere that wrist motions are very complicated thatís why so far nobody was able to create math model of the wrist motions.
IMO, if the wrist is near neutral position, from the wrist flexion/extension standpoint, the wrist deviations can move in plane. If there is a lot of wrist flexion or extension the motion would be restricted and more complicated.