Trying to recreate this forearm motion

[saqademus]

Hi,


For a university project I have to exactly recreate the twist of the forearm. I've been taking tutorial classes and vids but they dont seem to prepare me for this task.


Could somebody please explain - ideally in a step by step process - how to do it?


Here is the pronation of the forearm I am trying to replicate:


[url]http://www.youtube.com/watch?v=pogIgxdMuFQ&context=C4784 f7fADvjVQa1PpcFPOZFZznwZQ3W91YwInJwZ1sT9mp1RiyOY [/url]=


Note: The drawing/shape isnt important; just the motion/mechanism!


Also notice how the radius (outer forearm bone) rotates in the socket on its axis but the ulna remains fairly rigid (at the elbow end anyway)


Thanks


-saqademus