Bladder Meridian
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BL-37
Needle Depth
1.0–2.0 cun
Needle Angle
90° (Perpendicular)
Body Area
Thigh — Posterior
Location
6 cun below Chenfu BL-36, on the line joing Chengfu BL-36 and Weizhong BL-40.
Main Actions
- Strengthens the lower back
Indications
Commentary
Like Chengfu BL-36, Yinmen BL-37 is also indicated for lower back pain that spreads down the Channel to the buttock and legs. It is even more frequently used for this disorder.
Direct moxibustion can also be applied on top to enhance the effect.
Classical Sources
Zhenjiu Jiayi Jing (针灸甲乙经 - The Systematic Classic of Acupuncture and Moxibustion): "Six cun below Chengfu (BL-36), between the two tendons." This earliest reference establishes the standard location of the point on the posterior thigh.
Leijing Tuyi (类经图翼): Added the specification "between the two tendons on the popliteal region," clarifying the anatomical landmark between the hamstring muscles.
Classical Indications: Traditional texts record the main indications as "lumbar pain, swelling of the outer thigh, and scrotal distension," indicating its use for pain conditions of the lower back and leg.
How to Locate
First locate Chengfu BL-36 in the middle of the gluteal crease and Weizhong BL-40 in the middle of the popliteal crease. Draw an imaginary line between these two points. Yinmen BL-37 is located on this line, 6 cun below BL-36 and usually 8 cun above BL-40.
Caution
The sciatic nerve lies directly beneath this point at the deep level. While not classified as a dangerous point, practitioners should be aware that deep needling may contact the sciatic nerve, which can produce strong electric sensations. This is generally therapeutic but may be uncomfortable for sensitive patients. Use appropriate needle depth and avoid aggressive manipulation if the patient reports sharp shooting pain. The area contains deep femoral artery and vein perforating branches laterally.
Needle Angle
90° (Perpendicular)
Depth Category
Deep
Standard Depth
1.0–2.0 cun
Needling Directions
Vertically 0.5–2 cun.
Expected Deqi Sensation
Local distension and soreness in the posterior thigh. Deqi often radiates downward along the posterior leg following the pathway of the sciatic nerve, sometimes reaching the calf or foot. An electric or lightning-like sensation traveling down the leg is common and indicates strong needle response.
Moxibustion
Recommended
Duration: 10–15 minutes
Cupping
Recommended
Bloodletting
N/A
Gua Sha
Recommended
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