족태양방광경 (BL)   >   BL30 백환수 (白環兪)
부위
엉치부위, 넷째 뒤엉치뼈구멍(the 4th posterior sacral foramen)과 같은 높이, 정중엉치뼈능선(median sacral crest)에서 가쪽으로 1.5寸.

In the sacral region, at the same level as the fourth posterior sacral foramen, 1.5 B-cun lateral to the median sacral crest.
Note: 1.5 B-cun lateral to the sacral hiatus, at the same level as BL34.
침구법
- 直刺 0.5～1寸
- 斜刺 0.7～1寸