Yin-Yang is the fundamental duality of everything in the universe
Yin means the shadow of the mountain, Yang means the sunny side of the mountain. Yin-Yang in the body is sometimes illustrated like a farmer bending over and working. The back and head are exposed to the sun, Yang, while the chest and abdomen and feet are in shadow, Yin.
Yin-Yang theory is foundational in Taoist cosmology and also in Chinese medicine theory. The famous symbol for Yin and Yang is called taijitu, the “symbol of the great ultimate reality”. It shows the black as Yin and the white as Yang in a constant state of harmonious movement. The key of this symbol is how the seed of Yin is within Yang, and the seed of Yang is within Yin.
Yin is dark, internal, receptive, hidden, in shadow, soft, heavy, cool, wet, in closer proximity to the Earth.
Yang is external, bright, active, exposed, lit-up, hard, light-weight, warm, dry, in closer proximity to Heaven.
Everything has a relative Yin-Yang nature, nothing is really ever pure Yin or pure Yang. Yin and Yang are mutually dependent, they exist always in relation to each other. Yin will transform into Yang in its most extreme aspect, the same for Yang. Just as when the sun is highest and brightest at noon (Yang) at that moment of peak it begins to descend into the cool and dark part of the day (Yin).
Yin-Yang Organ Theory
In Chinese medicine organ theory (zangfu) there are twelve organs, and each organ has a Yin or Yang assignment which describes something important about its nature.
Yin (zang) organs are solid organs that store qi, blood, fluids, or other substances. These organs generally benefit from nourishment and suffer from depletion. Yang (fu) organs are hollow and are meant to be active in transformation and movement of substances, not storage. They generally benefit from harmonizing and moving and suffer from stagnation.
The Lung, Heart, Spleen/Pancreas, Liver, Kidney, and Pericardium organs are Yin. They store substances. The most Yin organ of all is the Kidneys, being the Water element, a very Yin element, and located low in the body. The Kidneys store our most important substance the jing, our ancestral life-force.
The Large Intestine, Small Intestine, Stomach, Gallbladder, and Triple-Burner organs are Yang. They are hollow and use the qi to digest, transform, extract nutrients, and eliminate waste.
Zangfu is an important component of diagnosis and treatment for internal medicine and of particular use with herbal medicine.
The Yin-Yang Structure of the Body
The body has its own relative Yin-Yang structure that can be helpful for diagnosing and treating musculo-skeletal issues including injuries, chronic pain, and degenerative diseases.
The back of the body, including the neck, shoulders, back, and the outer parts of the arms and legs are Yang. The front of the body including the face, chest, abdomen, and inner parts of the legs and arms are Yin. The skin is Yang relative to the internal organs. The head is Yang relative to the feet, which are closer to the Earth and therefore Yin.
This can be broken down even more: the upper back is Yang while the lower back is Yin. The chest is Yang while the abdomen is Yin. the tops of the feet are Yang while the soles of the feet are Yin.
On the back the spinal curves have relative Yin-Yang relationships. The inward curves of the cervical and lumbar are Yin, while the outer curves of the thoracic and sacral and Yang. Yet the cervical and thoracic are Yang in relation to the lumbar and sacral because they are higher up on the body, more exposed, closer to Heaven.
In treatment this is relevant. The Yin structures tend to suffer from weakness and the Yang structures from tension. However, Yin is not the same thing as deficiency or weakness and Yang is not the same thing as excess or tension.
Low back pain is often from weakness in the corresponding Yin aspect- weak abdominal muscles mirroring the low back. Low back pain also shows up as tension in the more Yang aspects of the spine- the lower thoracics and upper sacral. Address abdominal weakness or coldness, and treat the upper sacral and lower thoracic tension to relieve low back pain.
Upper back pain is Yang-on-Yang tension, within which a hidden Yin weakness can be found. Releasing the tight trapezius, supraspinatus, and infraspinatus is one part of treatment, but then look for overstretched and weak rhomboids, and instability in the cervical curve. Ribs that are stuck or “out” in the back will often have a corresponding tenderness in the anterior ribs. Create leverage for treatment of stubborn and guarded upper back pain by treating the anterior sterno-costal area.
Shoulder pain can be a Yang type where the joint is very stiff, difficult to move, perhaps inflamed. Look for weakness in the low back, abdomen, or legs that might be contributing to overuse of the shoulder, or may undermining its ability to heal properly.
Shoulder pain that is more “nervy” and weak is a Yin type. The affected shoulder will often present as lower, either on the top of the shoulder joint or in the scapula. The patient may not want the affected shoulder to be touched or treated. The Yang tension will often be found on the opposite side of the upper back, especially around the vertebrae and paraspinal muscles.
Yin-Yang diagnosis can go even further for pain conditions, especially with incorporating in-depth channel theory, zangfu treatment, and herbal remedies for maximum benefit.
Yin-yang in the body should be functional and natural, creating a harmony of movement for our lives. When it is pathological we use the same principles of balance to address pain and dysfunction.