Pulse diagnosis is one of the foundations of Chinese medicine. The practice of taking the pulse at the wrist on the radial artery goes back to the book Classic of Difficulties from 100 AD In Chinese medicine the pulse is felt on both the right and the left, with three different positions on each side. When feeling for the pulse we observe things like the rhythm, speed, and regularity, and also other qualities such as depth and strength.
Even the tension in the vessel and the thickness of the blood in it can give important information about a person's overall health. The practice of taking the pulse and using it as a tool to glean information about the body as a whole is based on a concept referred to as “the part representing the whole.” This concept is mirrored in Chinese medicine with facial diagnosis, eye diagnosis, and tongue diagnosis, three similarly useful tools. Other alternative therapies that follow this concept include ayurveda, irridology, chiropractic, and reflexology.
Each pulse position reveals what is going on in different areas of the body. The first position, closest to the crease of the wrist, gives information about the organs in the thoracic cavity (heart and lung) and diseases in the chest and head. The second position, just behind this, gives information about the organs in the abdominal cavity (liver, gallbladder, stomach, spleen, pancreas) and diseases in the area between the diaphragm and belly button. The third position gives information about the organs in the pelvic cavity (kidneys, bladder, reproductive organisms, intestines) and diseases from the belly button down to the feet.
There are many factors that can influence the pulse. Because of this, the most ideal time to take the pulse is first thing in the morning, when it is unaffected by work, eating, or emotions. Another factor that can affect the pulse is seasonal shifts; they will generally be more favorable in the summer when it is hot, and deeper in the winter when it is cold. Furthermore, men's pulses tend to be reliably stronger than women's, and the pulses of children are more rapid while the elderly have slower pulses.
Even pregnancy can affect the pulse because of all of the extra fluids circulating in the mother's body. This gives the pulse what is referred to as “slippery” quality, described in the classics ever so poetically as “pearls rolling in a basin” or “raindrops rolling on a lotus leaf.” Slippery pulses can also be found when there is edema or conditions of excess mucus and phlegm.