Which point is 1 cun lateral to Chengjiang REN-24, over the mental foramen?

• A. GV 28
• B. M-HN-14 BÍTŌNG
• C. M-HN-9 TÀIYÁNG
• D. M-HN-18 JIǍCHÉNGJIĀNG

Answer: (D)

Chengjiang REN-24 sits in the center of the mentolabial groove on the chin. The mental foramen is the small opening on the front surface of the mandible where the mental nerve exits, located just lateral to the midline under the lower lip. A point described as 1 cun lateral to Chengjiang REN-24 and over the mental foramen corresponds to Jiāchéngjiāng, which sits right at that foramen. This makes Jiāchéngjiāng the correct choice because it is the named point positioned over the mental foramen and referenced by that lateral distance from REN-24. The other points are in different regions and do not align with the mental foramen.