CG Papers and Abstracts Dealing with Muscles / Skin Deformation by Christopher Evans: http://chrisevans3d.com/reference.htm
Basic concepts behind the muscle rigs by Peter Shipkov : http://petershipkov.com/development/muscles/tutorial.htm
Some resource and reference video on muscular anatomy :
http://www.youtube.com/watch?v=9WFiE-jDZ0g&feature=related
http://www.youtube.com/watch?feature=endscreen&v=Xu4Htf2Ds9w&NR=1
http://www.youtube.com/watch?v=mcZ8OVTsi7E&feature=related
http://www.youtube.com/watch?v=qmOxpS18KOQ&feature=related
http://www.youtube.com/watch?v=g8Krn9dIabk&feature=related
http://www.youtube.com/watch?v=o9Rayocdgyc&feature=related
http://www.youtube.com/watch?v=OSelrhJzKJ4&feature=related
http://www.youtube.com/watch?v=hNnZDGihJDs&feature=related
http://www.youtube.com/watch?v=Os2zuEuGCIw&feature=related