When you study acupressure or acupuncture, you don’t use inches or centimeters. The ancient Chinese people used the unit called cun, which is the width of your thumb at the joint, for measurement. For example, there’s an acupressure point called Pericardium 6 which is good for motion sickness and nausea. It’s located two cun from the inner wrist crease. And it’s the thumb of the receiver, not the practitioner. I think it makes sense and it’s very smart because everyone’s body size is different and one size doesn’t fit all. So you can’t say it’s two inches from this point on everyone.
Interestingly, one cun is also the same width as the middle section of your middle finger.
Two cun is the same width as the three fingers put together around the first joint. One and two.
And the distance from the fingertip to the second joint on the index finger
By the way I’ve never seen cun in a plural form. It’s always cun no matter how many thumbs are involved. You don’t put s at the end.
And three cun is the same width as the four fingers put together. One, two and three.
So another maybe faster way to find Pericardium 6, which was 2 cun away from the wrist crease, is to put three fingers from the wrist crease.
Knowing these alternative measurement is handy because sometimes the location is specified as “7 cun from so and so.” So instead of using thumbs all the way you can just use a group of fingers.
On a side note, thumb was also used as a basis for 1 inch which is 2.54cm. So I measured my own thumb at the joint and my thumb is 7/8 of an inch or 2.2 cm. But at the base of the nail it was exactly 2 cm. Then I got curious and measured my hand spread open. From thumb to pinky it was 8 inches, little bit over 20 cm. Trivial information but it may come in handy someday.
9-28-15 What is Cun? http://bit.ly/mm-092815