Which San Jiao point lies 3 cun proximal to SJ-4, level with and on the ulnar side of Zhīgōu SJ-6, in the depression between the ulna and the extensor digitorum communis muscle?

• A. SJ-6
• B. SJ-7
• C. SJ-8
• D. SJ-9

Answer: (B)

The key idea is reading the location along the San Jiao channel by distance from SJ-4 and by spatial relation to SJ-6. Being 3 cun proximal to SJ-4 places you on the forearm above the wrist along the SJ line. The description then specifies a position at the same level as SJ-6 but on the ulnar (little-finger) side, in the hollow between the ulna and the extensor digitorum communis. That precise spot is SJ-7, which sits just proximal to SJ-6 on the ulnar side and in that depression between the ulna and the extensor digitorum communis. The other points would have different relationships to SJ-4, different proximities, or different anatomic hollows, so they don’t match this description.