One word... morph targets...

er... :blushing: that's two words... but anyway...

Bones are a cumbersome way to make mouth movements (other than the obviously cartoonish "jaw drop" that we see in Tex Avery stuff).  Using C5Pro I create morph targets in the vertex modeller (using the morph tab) for the phenomes and let the software build the sliders.  The manual does an adequate job of explaining the basics so I won't go into details.  The nice thing is that you can combine phenomes with the sliders and make permutations that you hadn't thought of (or reduce the number of phenomes that you need by setting 50% of, say, "oo" to be "oh", etc).

Hope that helps...

Ken