Hi. sorry I haven't seen your reply. This forum moves too fast :) The image was from Anatomy Tools. It's a reference bust. http://www.anatomytools.com/bust-male-p137.php
Going of what DireWolf said, you don't need to focus on the muscles right now. Try to get a good bust first, and get the details that are specific to his character i.e the ears,chin, etc.