This document discusses the extrapyramidal system and extrapyramidal disorders. It begins by defining the extrapyramidal system and its anatomy, which includes structures like the basal ganglia and brainstem nuclei. It then covers topics like the classification, features, etiology, and pathophysiology of extrapyramidal disorders. Specific disorders discussed in more detail include Parkinson's disease and Huntington's disease. The key features, diagnoses, differential diagnoses, treatment approaches, and pathologies of these two conditions are summarized.