This is an account of a large amount of research work on the cerebrospinal, sympathetic and autonomic innervation of muscle, all correlated with the investigations of other workers, which are subjected to a critical review. Chemical and pharmacologic investigations are reported as well as histologic studies and physiologic experiments. The chief practical application of interest to practicing physicians relates to the muscular atrophies. In a general way, so-called spinal muscular atrophy, including amyotrophic lateral sclerosis and neuritic muscular atrophy (Charcot-Marie type) are related to the cerebrospinal motor system, while it is claimed that in muscular dystrophy the sympathetic and autonomic innervation is at fault. The author has found that benefit has been obtained from treatment with atropine and pilocarpine, provided the motor nerve endings have remained intact.