CBD Oil as Muscle Relaxant: So how does it work? Liked we explained briefly, muscle relaxers work by severing neurological communications between the CNS (the brain) and the actual muscles themselves. Spastic signals from the CNS come to a stop, and the muscles relax and shut down. We all know that CBD is an excellent pain modulator within the central nervous system, but does it function at the actual site of muscles as well? Think of painkillers as affecting the brain, and muscle relaxers as affecting actual muscles. Instead of functioning through the CNS by blocking pain transmission at the brain, they function at the actual site of the muscle(s). You can see then, the difference between the function of painkillers and muscle relaxants