The aim of this study is to provide anatomical information of Fengchi (GB20) including applicable needling depth and related physiological effect. Methods: The contents about GB20 were extracted from literature. Then we investigated the clinical effect and needling feature (depth/angle) of GB20, searching on-line databases like 'Oasis', 'RISS', 'DBpia', Pubmed'. Results: According to the classic text, the needling depth of GB20 is 9.3-46.5 mm, When acupuncture is applied at that level, stimulatable anatomical structures were skin, semispinalis capitis, rectus capitis posterior minor, rectus capitis posterior major, greater occipital nerve, third occipital nerve, suboccipital nerve, posterior atlanto-occipital membrane, occipital artery and vein, vertebral artery.
Conclusion:In applying GB20 for acupuncture treatments, peripheral disorders are treated by stimulating the semispinalis capitis, the greater occipital nerve, the third occipital nerve, and central disorders are treated by stimulating the rectus capitis posterior minor, the rectus capitis posterior major, the suboccipital nerve.