Bladder meridian
BL-40 (Wěizhōng, 委中) — Supporting Middle
- Meridian
- Bladder (BL)
- Anatomical view
- posterior
- Point classification
- He-sea and Earth point of the Bladder channel; traditional command point for the lumbar back.
- Depth reference
- 0.5-1.0 cun perpendicular only with precise popliteal anatomy; avoid the popliteal vein, artery, and tibial nerve
- Moxibustion
- No direct moxa over the popliteal vessels; no point-specific indirect-moxa recommendation was found
- Reference aliases
- BL40; Weizhong; 委中; Supporting Middle
Anatomical location
At the midpoint of the popliteal crease behind the knee.
Traditional actions
Traditionally clears heat, cools blood, relaxes sinews, and benefits the low back.
Recorded indications
Primary: Reference uses include acute low-back pain, sciatica, knee pain, leg weakness, and heat-related skin eruptions.
Secondary: Secondary uses include abdominal pain, vomiting, and urinary difficulty.
How to read this reference
AcuAtlas separates anatomical location, traditional classification, recorded actions, indications, insertion-depth references, and moxibustion notes because these fields answer different study questions. The location statement is the orientation anchor. The classification and actions describe traditional reference categories, while indications summarize how checked educational sources associate the point with established teaching material. They are not a recommendation to select or stimulate the point.
Depth and moxibustion entries are reproduced as bounded reference notes rather than procedural instructions. Individual anatomy, technique, angle, clinical setting, and local professional standards can change what is appropriate. Review the cited documents and supervised training material before using any technical field. The normalized map coordinate is included only to place the point on the matching AcuAtlas body plate; it is not a substitute for palpation or anatomical assessment.
Sources
References displayed on this page were recorded with the point dataset.
- WHO Standard Acupuncture Point Locations in the Western Pacific Region (2008) BL40, p. 119
- Acupuncture.com Point Locator - Urinary Bladder 40 English name, classification, indications, functions and needling
- TARA Acupuncture Knowledge Base BL 40: special-point role, indications, method, tibial innervation and popliteal vasculature
- WHO Guidelines on Basic Training and Safety in Acupuncture Section II, 5.1-5.2, direct moxa near major vessels and circulatory-system precautions
Frequently asked questions
Where is BL-40 located?
At the midpoint of the popliteal crease behind the knee.
What reference actions and indications are recorded for BL-40?
Traditionally clears heat, cools blood, relaxes sinews, and benefits the low back. The dataset lists these primary indications: Reference uses include acute low-back pain, sciatica, knee pain, leg weakness, and heat-related skin eruptions. Secondary indications are recorded as: Secondary uses include abdominal pain, vomiting, and urinary difficulty.
Is BL-40 safe during pregnancy?
This dataset does not identify BL-40 as one of its five mandatory pregnancy-caution points. That is not a declaration of safety. Pregnancy-related point selection requires individualized assessment by a qualified clinician.