Which BL point is located 1.5 cun lateral to the lower border of the spinous process of L4?

• A. BL24
• B. BL25
• C. BL22
• D. BL23

Answer: (B)

Understanding the back-point map: on the Bladder channel, each point along the back is located about 1.5 cun lateral to the posterior midline at the level of a specific vertebra. The lower border of the L4 spinous process marks the level you’re using, and 1.5 cun to the side that level corresponds to BL25. This point is the Dachang Shu, the back-shu point for the Large Intestine, and its location is defined precisely by that vertebral level and distance from the midline. The other options sit at different lumbar levels (not at L4), so they don’t match the description. Therefore, the 1.5 cun lateral to the lower border of L4 identifies BL25.