Which point is located on the extensor aspect of the thumb, at the junction of lines along the radial border of the nail and the base of the nail, approximately 0.1 cun from the corner of the nail?

• A. LU 11
• B. LI 1
• C. LI 4
• D. LI 5

Answer: (A)

This question tests precise point location on the hand, specifically the nail-edge anatomy used for Jing-well points. The description points to the Lung channel’s Jing-well point on the thumb: it sits on the extensor (dorsal) aspect at the radial border of the nail base, about 0.1 cun from the corner of the nail. That exact spot is LU11, the Jing-well point of the Lung channel.

The other options lie on different fingers or areas, not at the thumb nail corner. For example, a point on the index finger nail is a different channel’s Jing-well point, while points between the first and second metacarpals or at the wrist are not at the thumb nail edge.