Baihuanshu 白環兪
Sacrum, 1.5 cun out from the median sacral crest, level with the fourth posterior sacral foramen.
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Sacrum · Gluteus maximus muscle
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On this page
1Where is Baihuanshu?
Sacrum, 1.5 cun out from the median sacral crest, level with the fourth posterior sacral foramen.
It is 1.5 cun beside the sacral hiatus and level with Xialiao (BL34).
Sacrum · Gluteus maximus muscle
2How do I find it on my body?
- Find the bony point under the dimple above each buttock: the posterior superior iliac spine.
- A line joining the lower edges of the two spines crosses the midline at the S2 spinous process.
- Midway from the posterior superior iliac spine to the S2 spinous process, feel for a dip: the second posterior sacral foramen (Ciliao, BL32).
- Move down from the second foramen: the second dip you meet is the fourth posterior sacral foramen. It is level with the sacral hiatus, between the two sacral horns just above the coccyx.
- At that height, press 1.5 cun out from the bony ridge down the middle of the sacrum (median sacral crest). This is half the 3-cun midline-to-shoulder-blade width.
A cun is a body-scaled unit of length. The precise way is to divide a bone length into equal parts (proportional bone cun); finger widths are a quick estimate.
- median sacral crest
- The bumpy vertical ridge down the middle of the back of the sacrum. It is made from the spinous processes of the sacral bones that fused together.
- sacral hiatus
- The opening at the lower back end of the sacrum where the bone does not close. You feel it as a small dip just above the top of the cleft between the buttocks.
- spinous process
- The bony spike sticking backward from the middle of each spine bone. The row of bumps you feel down the middle of the back is these, and they serve as the counting marks for back points.
- gluteus maximus
- The large, thick muscle that forms the buttock. It swings the leg back and gives power for climbing stairs and standing up.
3Before you press
- Do not press this point during pregnancy.
- Points over the low back and sacrum are traditionally avoided in pregnancy (WHO acupuncture safety guidelines, 1999).
- Avoid broken or swollen skin and press only to a comfortable level.
- Acupressure is not a substitute for medical care.
4How has it been used traditionally?
- The lowest point of the 1.5-cun back line; the name means 'white ring shu'.
From traditional texts — not a claim of effect.
?FAQ
Where exactly is Baihuanshu?
Sacrum, 1.5 cun out from the median sacral crest, level with the fourth posterior sacral foramen. It is 1.5 cun beside the sacral hiatus and level with Xialiao (BL34).
How do I find Baihuanshu?
Find the bony point under the dimple above each buttock: the posterior superior iliac spine. A line joining the lower edges of the two spines crosses the midline at the S2 spinous process. Midway from the posterior superior iliac spine to the S2 spinous process, feel for a dip: the second posterior sacral foramen (Ciliao, BL32). Move down from the second foramen: the second dip you meet is the fourth posterior sacral foramen. It is level with the sacral hiatus, between the two sacral horns just above the coccyx. At that height, press 1.5 cun out from the bony ridge down the middle of the sacrum (median sacral crest). This is half the 3-cun midline-to-shoulder-blade width.
Can I press it during pregnancy?
Do not press this point during pregnancy.
What should I watch out for?
Do not press this point during pregnancy. Points over the low back and sacrum are traditionally avoided in pregnancy (WHO acupuncture safety guidelines, 1999). Avoid broken or swollen skin and press only to a comfortable level. Acupressure is not a substitute for medical care.
Sources
- Location: WHO Standard Acupuncture Point Locations in the Western Pacific Region (2008), p. 114
- Standard comparison: Chinese national standard GB/T 12346-2021 (Nomenclature and location of meridian points), p. 18 — same location
- Korean anatomical terms: KMLE medical dictionary
- Traditional-use cross-check: AcuAtlas dataset (CC BY 4.0)
- Classical record: Zhenjiu Jiayi Jing vol. 3, sec. 8
- Safety: WHO Guidelines on Basic Training and Safety in Acupuncture (1999), p. 20 — lumbosacral points in pregnancy
- 3D: computed on Z-Anatomy (CC BY-SA 4.0) · BodyParts3D © DBCLS
Positions computed from the WHO standard locations (2008) on Z-Anatomy (CC BY-SA 4.0) · BodyParts3D © DBCLS. For reference only — not a substitute for diagnosis or treatment. See a clinician if you are unwell.