<prompt> Central muscle relaxants act by -Decreased nerve conductionInhibits spinal polysynaptic reflexesBlock conduction across NM junctionCNS depression  <response>: Ans. is b i.e., Inhibits spinal polysynaptic reflexes Centrally acting muscle relaxants selectively depress spinal and supraspinal polysynaptic reflexes involved in the regulation of muscle tone without significantly affecting monosynaptic mediated stretch reflex. 