--Jing Luo are the main channels of communication and energy distribution in the body.
--Link interior Zang Fu organs with various tissues of superficial areas of the body. In this way they allow for internal adaptation to external change.
--They connect different superficial areas of the body.
--The Jing Luo are more external (and more Yang) than the Zang Fu Organs. When pathogens penetrate the body from the Exterior, they usually penetrate the superficial channels and then the main channels and finally the Zang Fu Organs.
--Jing Luo cover the entire body.
Every part of the musculoskeletal system is related to a main meridian and its associated sub-meridians.
Via the main channel, every part of the body associated with a given internal Organ can be affected by imbalance in that Organ.
Example: The Bladder channel: connects the small toe, lateral aspect of foot and ankle, posterior aspect of leg, buttocks, sacroiliac and dorsal region, occiput, vertex, central frontal region and inner canthus of eye.
Knowing the pathway of the channels, we can make connections in symptoms as diverse as itchy eyes, occipital headaches, lumbar pain and spasms in the gastrocnemius. For example, the Heart channel begins in the axilla and ends on the small finger. It has long been noted in western biomedicine that in the case of myocardial infarction, the pain often travels along this channel. TCM provides a link between this external muscular pain and an imbalance in the associated internal Organ.
We have 12 bilateral Meridians. The two special vessels (the Conception Vessel and the Governor Vessel) are not bilateral. They are singular channels, which follow the midline of the body, one in front and one on the back.
There are a number of ways in which the Primary Meridians can be classified. One method is to classify them into two groups, according to their polarity of Yin and Yang. The Chinese determined that some of the Meridians are predominantly of Yin energy, and some are predominantly of Yang energy.
The Primary Meridians are also grouped together in coupled pairs, each Yin meridian being coupled to a specific Yang meridian. The pairs are coupled according to the table above, i.e., Lung with Large Intestine, Spleen with Stomach, Heart with Small Intestine, Kidneys with Bladder, Pericardium with San Jiao, and Liver with Gall Bladder.
Another way of classifying the Meridians is based on the main location of the Channel and its terminal point. Six Meridians are located on the upper portion of the body, and start or end on the fingers. The other six Meridians are located on the lower portion of the body and end or start at the toes.
The Chinese determined that the energy flows from one meridian to the next in a continuous and fixed order. It flows from meridian to meridian in a two-hour cycle, making the complete circuit once a day.
This cycle is known as the Horary cycle. As the Qi makes its way through the meridians, each meridian in turn, with its associated organ, has a two-hour period during which it is at maximum energy. The Horary Effect is recognizable by measurable increases of Qi within an organ system and meridian during its time of maximum energy. (Qi is, of course, present within every organ system all the time; its level simply fluctuates according to the Horary Cycle.)
Just as each organ system has a waxing and waning two hour period of maximum energy on the Horary Cycle, there is also the minimum energy effect of the organ on the opposite, side of the cycle, 12 hours apart. An example of this is that while the Lungs have maximum energy from 3-5 AM, the Bladder on the opposite side of the table is at its minimum energy level, 3-5 PM. Qi begins entering the Lungs at 3 AM, and has reached its maximum concentration in the organ at 4 AM. By 5 AM it has done its tonification and repair work and is moving into the Large Intestine channel.