What type of point is BL-40 categorized as?

BL-40, also known as "Weizhong" or "Middle of the Crook," is categorized as a He Sea point. He Sea points are traditionally located on the lower part of the body and are associated with the management of organ function, particularly in relation to digestion and absorption, as well as influencing fluids in the body. In the case of BL-40, it is positioned at the back of the knee, which aligns with the characteristics of He Sea points being situated at the joint areas, and it helps in the control of the bladder and the lower jiao (lower abdomen), which plays a crucial role in fluid metabolism.

Each category of acupuncture points serves a specific purpose based on their location and the organs they relate to. He Sea points are known for their ability to influence the qi (energy) and blood in the lower regions, and they are integral for treating various conditions such as stagnation and excess. Therefore, BL-40's classification as a He Sea point is essential in understanding how it can be utilized in acupuncture for specific therapeutic effects, particularly in treating issues related to the bladder, lower back pain, and knee problems.