organization of motor subsystems DESCENDING SYSTEMS upper Motor Neurons Motor Cortex BASAL GANGLIA Planning, initiating, and Gating proper initiation directing voluntary movements of movement Brainstem Centers CEREBELLUM Basic movements and Sensory motor postural control coordination Local circuit neurons Re Motor neuron pools flex coordination Lower Motor Neurons SPINAL CORD AND BRAINSTEM CIRCUITS SKELETAL MUSCLES o 2001 Sinauer Associates, Incorganization of motor subsystems