Abstract:Based on the analysis of 53 cases of derangement of Lumbar facet joints,and the cause of Lumbago,the disease was classified into two types:the peri-articular and the intraarticular type.Through microanatomical observation of 100 posteromedial branch of Lumbar spinal nerve from 10 cadavers,it was shown that the facet joints were chiefly innervated by posteromedial branch.They were compressed by multiple factors along their course and passage.The pathogenesis and principle of manipulative therapy of the ailment were explored based on the neuroanatomical and physiological data.