Aim : Since it was reported that acupuncture at Danchu (CV17) was critical when the needle penetrated through the congenital sternal foramen, we decided to study the incidence of the congenital sternal foramen, as well as the distance between the body surface and the back side of the sternum at Danchu, in order to know the safe depth of acupuncture penetration.
Method : 1) We selected 51 cadavers to examine the incidence of congenital sternal foramen and, if any, to study its structure. We also selected 21 cadavers to measure the cadaveric thickness of the sternum. 2) We selected 31 people to measure the incidence of the congenital sternal foramen and the distancebetween the body surface and the back side of the sternum at the point of Danchu.
Results : 1) We found one out of 51 cadavers which had congenital sternal foramen. The location of the foramen was at the height of the fourth intercostal space. It was round-shaped, 9mm in diameter, and filled with hard connective tissue. The thickness of the sternum ranged from 9 to 15mm with an average of 11.5 ± 2mm. 2) There was no one who had the congenital sternal foramen among the 32 people. The distance between the body surface and the back side of the sternum ranged from 11 to 31mm with an average of 18.8 ± 5mm.
Conclusion; 1) The incidence of the congenital sternal foramen in this study was one in 51 cadavers and zero in 32 people. 2) We concluded that acupuncture at Danchu within a depth of 10mm is sufficiently, even if congenital sternal foramen exists.

Acupuncture to Gaohuang carries a risk of causing pneumothorax because it reaches the lungs at deep portion. This study was designed to consider a safe depth for acupuncture to Gaohuang.
1) We inserted a needle to Gaohuang on both sides of a cadaver to examine the location of the needle tip and measure the distance from the body surface of the left Gaohuang to the pleura. The tip was located at the fifth intercostal region on both sides, and the distance was 44 mm with a rib thickness of 10 mm. 2) Using 104 students, we inserted a needle to the left Gaohuang until the tip reached the rib, and measured the distance between the bodysurface and rib. The minimal distance was 14 mm. 3) We inserted a needle to Gaohuang on both sides of two males and took CT-radiographs to examine the location of the needle tip and measure the distance from the body surface of Gaohuang to the pleura. In a man of standard body size, the needle reached the rib on the left and the intercostal region on the right. The thickness of the left rib was 10.9 mm, and the distance from body surface to pleura was 33.6 mm on the left and 28.4 mm on the right. In a man of thin body size, the needle reached the rib on both sides, with the rib thickness was 9.8 mm on the left and 8.8 mm on the right. The distance from body surface to pleura was 29.4 mm on the left and 31.8 mm on the right. The above results showed that needle insertion within 19 mm (the minimal value of the measured distance between the body surface and rib + the half thickness of the rib) is safe.