The creation of computer-animated human faces is a long-standing and challenging problem since the early 1970s. There are numerous approaches to facial animation, but to this day no general-purpose system exists that solves the problem in a manner satisfying the needs of all practical applications. An obvious approach to achieve generality is the simulation of the inner workings of a real face. The ultimate goal is to have the full range of conformation and expressiveness in the face emerge "naturally" through precise modeling of the anatomical structure and accurate simulation of tissue...