Numerous experiments reported in the biomechanical literature have shown that soft tissues are highly nonlinear viscoelastic materials. Attempts to model their mechanical behaviour have led to different kinds of mathematical relationships depending on the approach adopted. The use of these models for the realistic simulation of skeletal soft tissues requires basic knowledge of the theory of nonlinear mechanics as well as knowledge of the associated incremental finite element methods. Although many documents have been published in these different areas, few of them give enough details to understand how the models are related to the underlying mechanical theory and how incremental methods are applied to achieve finite element simulations. This report has been developed, as part of the European Esprit project CHARM, to provide an overview of the available models in light of theoretical mechanics and finite element methods, for the realistic simulation of the human muscles, tendons and skin.