The pyramidal system was the primary pathway for voluntary movement. The extrapyramidal system is another motor system that is important for control of movements. Neuronal activity for this motor system begins in the cerebral cortex and ultimately exerts an influence on the lower motor neurons. The pathways are indirect, as opposed to the direct pathways of the pyramidal system. The long axons of the corticospinal tract and corticobulbar tract make only one synapse with the lower motor neuron, so the pyramidal system is called monosynaptic. The extrapyramidal system, however, is polysynaptic.The major extrapyramidal nuclei are the basal ganglia. Remember that the basal ganglia is composed of the Globus Pallidus, Putamen, and Caudate Nucleus. Together, the Globus Pallidus and Putamen are called the Lenticular Nucleus. Together, all three are called the Corpus Striatum. Other structures related to the extrapyramidal system include the substantia nigra, red nucleus, subthalamic nucleus, and reticular formation of the mesencephalon. The cerebellum is also thought of as contributing to the extrapyramidal system.The extrapyramidal system works by modifying neural impulses that originate in the cerebral cortex. Impulses generated at the primary motor strip are sent via the extrapyramidal fibers to the basal ganglia. In a complex network of pathways, the structures of the basal ganglia modify impulses and send information to each other. Some fibers will then be directed down to synapse with the lower motor neurons. Other fibers are routed through the thalamus and back up to the cortex.