The methods of nonlinear systems and control theory were applied to a simple musculoskeletal system with one joint and two muscles in this paper. For this purpose, a nonlinear input-affine state-space model has been developed for this system with a flexor and an extensor muscle taking into account the nonlinear muscle and movement dynamics. Two types of controllers were designed: a linear pole-placement servo designed for the locally linearized model, and a nonlinear controller based on asymptotic output tracking method. It is expected and forward that during a movement with a large range of motion the nonlinearities of the system will be dominant and the nonlinear methods will outperform the linear ones. The output reference tracking properties of the controllers have been investigated by simulation and it has been found that the nonlinear controller gives more accurate tracking with no overshoots than the linear one.