It is an alternative route for the mediation of voluntary movement. It is responsible for large muscle movement such as the arms and the legs as well as for fine motor control. It facilitates the extension and inhibits the flexion in the upper extremities.
It is small and rudimentary in humans. In some other primates, however, experiments have shown that over time, the rubrospinal tract can assume almost all the duties of the corticospinal tract when the corticospinal tract is lesioned.