Bladder Channel

Weizhong BL-40

Chinese: 委中

Pinyin: Wěi Zhō

Location

At the midpoint of the popliteal crease, between the tendons of biceps femoris and semitendinosus muscle. 

How to locate

First flex the knee slightly in order to reveal the popliteal crease, where Weizhong BL-40 is located at the center. 

Main actions

  1. Cools the blood
  2. Clears Summer-Heat
  3. Removes obstructions from the channel and eases lower back pain
  4. Benefits the Bladder

Indications

Fever Thirst Sciatica Delirium Knee pain Headaches Heat stroke Irritability Lower back pain Red skin rashes Aversion to cold Burning urination Lower back stiffness Feeling of heaviness Epigastrium discomfort

Needling

Vertically 0.5–1.5 cun.

Caution: Popliteal nerve, artery and vein lie deep to this point.

Commentary for Weizhong BL-40

Weizhong is an important point with various functions. 

First of all, it clears Heat and cools Blood, so that it is widely used for skin diseases due to Heat in the Blood. 

It clears Summer-Heat. Therefore it treats Heat stroke that causes vomiting, diarrhoea, fever, delirium, headache, irritability and red skin rashes during summer time. 

It also clears Damp-Heat from the Bladder, so as to treat various unitary symptoms such as burning urination. 

It also removes obstructions from the Channel, so that it is able to relax the sinews and benefit the lower back. In fact, it is one of the most important distal point for any types of lower back pain, but it is more recommended for acute and Excess patterns. Due to BL-40's nature of cooling Blood, it is not recommended to be used for weak patients with severe Deficiency or Coldness symptoms. In these type of back pain cases, Kunlun BL-60 is more suitable. 

As for the location of the lower back pain, BL-40 is more recommended if the ache is either bilateral or unilateral instead of being on the spine. Other typical manifestations are sciatica, lower back stiffness and knee pain.