What is a significant risk associated with perpendicular insertion of GB-21 (jianjing) in thin patients?

In the context of acupuncture and the anatomical locations of points, the significant risk associated with perpendicular insertion of GB-21 (Jianjing) in thin patients is the potential to injure the lungs. GB-21 is located at the highest point of the shoulder, midway between the spine and the acromion process. In thin individuals, there may be less subcutaneous fat and muscle tissue to protect the underlying structures, such as the lungs.

Perpendicular insertion at this site can lead to the needle reaching too deep, particularly in those who are slender, resulting in a risk of puncturing the pleura, which can in turn lead to a pneumothorax—a condition where air enters the pleural space and causes lung collapse. Therefore, due to the anatomical proximity and the reduced buffer of soft tissue in thin patients, the risk of lung injury is significant.

While other potential injuries, like those to the trapezius muscle, phrenic nerve, or suprascapular artery, may exist, they are not as directly associated with the perpendicular insertion of this specific point as the risk of lung injury. Understanding the anatomical relationships and variations among patients is crucial in practicing safe acupuncture techniques.