- We propose significant simplifications in muscle modeling and simulation to facilitate real-time anatomical skin deformation for full-body articulated characters. The muscle shape is a function of an animated quadratic Bézier action curve and control rings derived from it. The action curve is uniformly sampled to derive control rings driven by a scaled sinusoidal equation to model fusiform shapes. A single spring is attached between the central control point and the midpoint vector between the extreme control points of the Bézier action curve. Care is taken to stabilize local coordinates for each muscle vertex to enable glitch-free skin deformation. The character's polygonal mesh is smooth-skinned using a twolayered approach: first to the joints, and then to the muscle vertices. Lastly we show how different prominent muscles can be reasonably approximated with the proposed fusiform model. A typical 4000-vertex character skinned with sixty four 72-vertex muscles is able to run ...