Which San Jiao point lies 3 cun proximal to SJ-4, between the radius and ulna on the radial side of the extensor digitorum communis muscle?

• A. SJ-5
• B. SJ-6
• C. SJ-7
• D. SJ-8

Answer: (B)

The question tests precise point location along the San Jiao channel using cun measurements and nearby anatomy. The spot described—3 cun proximal to SJ-4, between the radius and ulna, on the radial side of the extensor digitorum communis—matches the location of Zhigou, San Jiao point six. To find it, start at SJ-4 at the wrist, then move roughly three finger-breadths toward the elbow along the forearm, keeping you on the radial side of the extensor digitorum communis tendon, between the two bones. This specific anatomical relation (between radius and ulna, radial side of EDC) distinguishes it from other SJ points, which lie at different distances or different sides of the forearm.