A Cun (“tsoon”) is an important reference for locating acupoints. In order to locate acupoints, you must understand how to measure the body using cun.
How big is a cun?
One cun is equivalent to the width of your thumb. Notice that I said the width of your thumb. A cun measurement is relative to body size. Since we are all different shapes and sizes, it makes sense that the width of our thumbs will vary too.
Directions for locating acupoints always reference cun in relation to an observable landmark.
For example, “Pericardium 6 (P 6) is located 2 cun proximal to the wrist crease on the palm side of the forearm.” (“Proximal” means closer to the trunk. In this case we move 2 cun closer to, or toward the elbow, rather than toward the palm of the hand.)
Based on those directions we can now locate P 6:
Step one – find the wrist crease on the palm side of the forearm.
Step two – measure 2 cun (or thumb widths) from the crease towards the elbow.
Step three – P 6 is located on the center line of the forearm, 2 cun proximal to the wrist crease. Use the images below for reference:
One cun is relative to body size
Adjusting cun measurements to locate acupoints
Notice the relative size difference between you and the person you are working with. If you are taller, your thumb will be thicker. Therefore, your cun measurement needs to be decreased for this person.
If you are shorter, your thumb width will be more narrow. Therefore, your cun measurement needs to be increased for this person.
In practice, this is much simpler than this lengthy explanation. So go practice! Compare your thumb width to those around you. Practice locating P 6 on different people. Once you put cun measurements into practice, it will make sense. I promise!