On the chest, in the third intercostal space, 4 cun lateral to the midline (Yùtáng REN-18), on the mamillary line, which point is described?

• A. ST 13
• B. ST 14
• C. ST 15
• D. ST 16

Answer: (C)

The chest points on the Stomach channel are laid out in the intercostal spaces, about four cun from the midline, along the mamillary line. Being in the third intercostal space means the space between the third and fourth ribs. Four cun lateral to the midline places you on the vertical line through the nipple (the mamillary line). So the location described corresponds to ST15. The other chest points lie in different intercostal spaces or lines and do not match this specific position.