AbstractMedical simulators play an important role in helping the development of prototype prostheses, pre-surgical planning and in a better understanding of the mechanical phenomena involved in muscular activity. This article focuses in modeling and simulating the activity of the jaw muscular system. The model involves the use of three-dimensional bone models and muscle modeling based on Hill type actuators. Ligament restrictions to mandible movement were taken into account in our model. Data collected from patients were used to partially parameterize our model so that it could be used in medical applications. In addition, the simulation of muscles employed a new methodology based on insertion curves, with many lines of action for each group of muscles. A simulator was developed, which allowed real time visualization of individual muscle activation under each correspondent simulation time. The model derived trajectory was then compared to the assembled data, remaining mostly within the convex hull of the mandible motion curves captured. Furthermore, the model accurately described the desired border movements.