Which BL point is located 5 cun below BL40 and midway between BL55 and BL57?

• A. BL 56
• B. BL 58
• C. BL 57
• D. BL 59

Answer: (A)

On the bladder channel, locate BL40 at the popliteal crease. The item tests using two reference cues: a vertical distance from BL40 (5 cun below) and a horizontal relationship between two nearby points (the midpoint between BL55 and BL57). The point that sits exactly 5 cun below BL40 and lies midway between BL55 and BL57 is BL56. That combination uniquely identifies it, which is why it’s the correct choice. The other points don’t meet both conditions simultaneously. Remember to gauge cun with your own body landmarks, using BL40 as the starting reference and then finding the midpoint between BL55 and BL57 along the same line.