Earth is Yang whereas water is Yin. Yet at the same time both earth and water can be more Yin or more Yang as a result of their temperature. Hot water is more yang than cold water. Another more complex example deals with ice. Although ice is colder than water and therefore more Yin, it is also harder than water and therefore more Yang. Traditional Chinese Medicine often detects imbalances in Yin and Yang using meridians and pressure points.
Pressure points are points on the body where the meridian lines are close to the surface of the skin and are therefore more easily accessible. If you look at a chart of meridians and pressure points, you will notice that pressure points are lined up along the meridian lines. When a Traditional Chinese Medicine practitioner meets with a patient, the practitioner will begin in much the same way as a medical doctor.
The patient will fill out a questionnaire and the practitioner will spend some time talking with the patient about symptoms, etc. However, after this, the practitioner will use some form of TCM diagnosis. This may involve looking at the eyes, tongue, or even the tip of the finger. However, the most common form of diagnosis is through the pulse. The practitioner will feel the wrist of the patient on the palm side.
Source: http://www.duyenpho.com