[Muscle as a system with parametric excitation].

A mechanical model for oculorotatory muscle consisting of a neurally controlled Voigt element in parallel with a mass and in series with a passive elastic element, is proposed. The magnitude of each element without the mass and the series elasticity is shown as a function of length and the viscosity as a function of velocity. The non-linear Voigt element is shown as a time-varying element to describe the activation of muscle. The characteristics resulting from the mathematical development agree well with the experimental data published for the operating range.