Which point is located between the radius and ulna, 2 cun proximal to SJ-4?

The point that is located between the radius and ulna, 2 cun proximal to SJ-4, corresponds to SJ-5. This acupuncture point, known as "Waiguan," is situated on the posterior aspect of the forearm in an area where both the radius and ulna can be palpated. It is considered part of the Sanjiao (Triple Burner) channel.

The significance of SJ-5 lies in its role as a known junction point and its effectiveness in addressing various conditions. It is used to promote the circulation of Qi and relieve pain, particularly in the arm and shoulder area. Additionally, SJ-5 has a noted influence on expelling exterior pathogens and is often utilized in the treatment of conditions like headaches and fever.

The other options, although related to the Sanjiao channel, are situated either at different distances from SJ-4 or in different anatomical locations, making them incorrect in terms of the specific criteria of this question. Understanding the precise anatomical relationships and locations of acupuncture points is crucial for effective clinical practice and accurate treatment.