Weizhong (BL40): Command Point for Lower Back Pain and Blood Stasis in TCM

Introduction to Weizhong

Weizhong (委中, BL40), meaning “Bend Center,” is located at the midpoint of the popliteal crease (the back of the knee). It is one of the most celebrated points in all of acupuncture — the classical “Command Point” for the lower back (腰背委中求).

The TCM saying “Yao Bei Wei Zhong Qiu” (腰背委中求) — “For problems of the lower back, seek Weizhong” — has been taught to acupuncture students for centuries. This single point, situated far from the lower back, can dramatically relieve acute lumbar pain through the Bladder meridian’s long pathway along the spine.

Location

Anatomical location: At the midpoint of the popliteal crease (the horizontal crease at the back of the knee), between the two tendons (biceps femoris and semimembranosus).

How to Find It

1. Sit or lie on your stomach
2. Bend the knee slightly
3. Find the horizontal crease at the back of the knee
4. The point is at the exact center of this crease
5. You may see or feel a visible vein — this is relevant for bloodletting therapy

Detail	Description
Meridian	Bladder (Foot Taiyang)
Point type	He-Sea point, Earth point, Command Point for the lower back
Region	Knee/posterior leg
Depth	1-1.5 cun perpendicular insertion

Key Functions

1. Treats Lower Back Pain (腰背痛)

Weizhong’s most famous and clinically important function:

• Acute lower back sprain — sudden onset, often from lifting or twisting
• Chronic lower back pain — dull, aching, worse with fatigue
• Sciatica — pain radiating down the leg along the Bladder channel
• Stiff lower back — difficulty bending forward or backward

2. Moves Blood and Removes Stasis (活血化瘀)

Weizhong is an important point for blood stasis:

• Bloodletting (pricking the visible veins) removes stagnant Blood from the channel
• Especially effective for acute lumbar sprain with vascular engorgement
• The released blood is often dark — indicating stasis

3. Clears Heat and Cools Blood (清热凉血)

The He-Sea point of the Bladder meridian clears heat:

• Heat in the Blood — skin rashes, eruptions
• Sunstroke — heat affecting the body
• Acute urinary symptoms — dark, burning urine

4. Relaxes Tendons and Muscles (舒筋活络)

• Knee pain and stiffness
• Leg cramps and spasms
• Hamstring tightness
• Calf pain

Clinical Applications

Acute Lower Back Sprain — The Classic Application

This is Weizhong’s strongest clinical use:

Acupressure technique:

1. The patient stands or sits
2. Press firmly on Weizhong with both thumbs
3. While pressing, have the patient slowly bend forward and then straighten up
4. Repeat 5-10 times
5. The movement combined with pressure helps unblock the channel

Bloodletting (practitioner only):

1. Identify engorged veins at the back of the knee
2. Sterilize the area
3. Prick with a sterile lancet
4. Allow 5-10 drops of dark blood to flow
5. Apply pressure and clean
6. Often provides immediate dramatic relief for acute sprain

Chronic Lower Back Pain

• Combined with local back points like Dachangshu (BL25) and Shenshu (BL23)
• Acupressure at Weizhong can be used daily as self-care

Sciatica

• Pain that follows the Bladder channel down the posterior leg
• Combined with Kunlun (BL60) for a powerful distal point pair

Common Point Combinations

Combination	Purpose
Weizhong (BL40) + Shenshu (BL23)	Lower back pain — distal + local
Weizhong (BL40) + Kunlun (BL60)	Acute lower back sprain, sciatica
Weizhong (BL40) + Dachangshu (BL25)	Chronic lumbar pain
Weizhong (BL40) + Yanglingquan (GB34)	Leg pain and spasms
Weizhong (BL40) + Chengshan (BL57)	Calf pain, hamstring tension

Acupressure for Self-Care

Daily Lower Back Maintenance

1. Sit on the floor with legs extended
2. Reach forward and press the center of the back of each knee with your thumbs
3. Apply firm circular pressure for 2-3 minutes per side
4. Combine with gentle forward bends to stretch the Bladder channel
5. Repeat 2-3 times daily

For Acute Back Pain

1. Stand with feet shoulder-width apart
2. Have a partner press Weizhong firmly on both sides
3. Slowly bend forward as far as comfortable while pressure is maintained
4. Straighten up slowly
5. Repeat 5-10 times — pain often decreases with each repetition

The “Four Command Points” of TCM

Weizhong is one of the famous Four Command Points (四总穴) taught to every acupuncture student:

Point	Command	Saying
Zusanli (ST36)	Stomach/Abdomen	”肚腹三里留”
Weizhong (BL40)	Lower Back	”腰背委中求”
Lieque (LU7)	Head/Nape	”头项寻列缺”
Hegu (LI4)	Face/Mouth	”面口合谷收”

Precautions

• Bloodletting should only be performed by trained practitioners with sterile equipment
• Do not needle deeply — the popliteal fossa contains the popliteal artery and nerve
• Avoid strong pressure on the back of the knee in patients with deep vein thrombosis
• Knee injuries — avoid direct pressure over acute trauma
• Pregnancy — use gentle pressure only

Key Takeaways

• Weizhong (BL40) is the Command Point for the lower back — “For lower back problems, seek Weizhong”
• Located at the center of the back of the knee crease
• Bloodletting at Weizhong provides dramatic relief for acute lower back sprain
• One of the Four Command Points of acupuncture, taught to every student
• Easy to use for self-acupressure combined with gentle bending movements

Disclaimer: This article is for educational purposes only. Bloodletting must be performed by qualified practitioners only. Consult a licensed acupuncturist for professional treatment.

Related Articles

• Kunlun (BL60): Key Point for Back Pain
• Zusanli (ST36): The King of Acupoints
• Hegu (LI4): The Universal Pain Point
• Understanding Pain in TCM