A fundamental problem in the field of motor neuroscience is to understand how our brain generates appropriate motor commands for precise movements effortlessly. The problem seems difficult since there are infinitely many possible trajectories and our musculo-skeltal system is generally redundant. We focus on the motor command representation and show that a simple strategy can solve the problem for a planar two-joints arm model. We also discuss the emergence of the muscle synergies, which may enable us to make natural motor behaviors with smaller degrees of freedom.