At the top of the chest, directly below ST-12, on the inferior border of the clavicle, 4 cun lateral to the midline, on the mamillary line, which point is described?

• A. ST 12
• B. ST 13
• C. ST 14
• D. ST 15

Answer: (B)

Precise chest-wall point locations along the stomach channel use the clavicle and the mamillary line. ST12 sits at the top of the chest in the supraclavicular fossa, about 4 cun lateral to the midline. Directly below it, on the inferior border of the clavicle and along the mamillary line (the vertical line 4 cun lateral to the midline), is ST13. That placement matches the description, which is why this point is ST13. ST14 and ST15 lie in intercostal spaces farther down the chest along the same vertical line, not on the inferior border of the clavicle, so they don’t fit the described location.