For your reference on FACS, I just stumbled upon this video. Nearly any anatomically possible facial
expression can be decoded from these AU and there combination.
Facial rig comparison between Standard
Blendshape vs Blendshape Combination System (BCS) by Daniel Pook-Kolb (stargrav.com/bcs.php).
With BCS you can create, combine (Combination-Sculpting) multitude of
facial expression with flexible inbetweening and interpolation to
simulate realistic skin behavior.
Apply here to learn: puppeteerlounge.com/apply
Facebook: facebook.com/puppeteerlounge
Twitter: @puppeteerlounge
P.S. The Gollum character by Weta Digital was based on such a system
for facial articulation. BCS is free for educational purposes.
Check out the research video by Disney which
shows the implementation of 3d scans of human eyes. The dilation of
pupil under different lighting condition is very cool.