Which BL point is 3 cun lateral to the midline, level with the lower border of the spinous process of the first lumbar vertebra (L1) and aligned with Sanjiaoshu BL‑22?

Which BL point is 3 cun lateral to the midline, level with the lower border of the spinous process of the first lumbar vertebra (L1) and aligned with Sanjiaoshu BL‑22?

• A. Bl 51
• B. Bl 52
• C. Bl 53
• D. Bl 50

Answer: (A)

The key idea is how Back-Shu/BL point locations are defined by spinal level and a fixed distance from the midline. The Sanjiaoshu point (BL-22) sits on the back at the level of L1, about 1.5 cun lateral to the midline. The described point is on the same horizontal plane as that BL-22 but 3 cun lateral to the midline, placing it on the BL channel at a specific lateral offset that matches that level. Among the options, this is the point that aligns with BL-22’s vertical line, so it’s the correct choice. The others would be at different vertebral levels or at different lateral distances and thus do not line up with BL-22.

The key idea is how Back-Shu/BL point locations are defined by spinal level and a fixed distance from the midline. The Sanjiaoshu point (BL-22) sits on the back at the level of L1, about 1.5 cun lateral to the midline. The described point is on the same horizontal plane as that BL-22 but 3 cun lateral to the midline, placing it on the BL channel at a specific lateral offset that matches that level. Among the options, this is the point that aligns with BL-22’s vertical line, so it’s the correct choice. The others would be at different vertebral levels or at different lateral distances and thus do not line up with BL-22.