“Zang Xiang” means visceral images and their manifestations. “Zang” refers to the internal organs; “Xiang” refers to the image or phenomenon. “Zang” and “Xiang” together refers to the internal organs and the external manifestation of their physiological and pathological states. Zangis the essence of Xiang, whereas Xiangis the external manifestation of Zang.
Those who are familiar with Conventional Western Medicine but focuses mostly on holistic observation and interpretation of functions, relationships, energy circulation, physiology, and pathology. Because of TCM’s focus on the intangible body (invisible matter or invisible system, e.g. the meridian system, 
; aura, 
; Qi, 
; spirit, 
), less attention has been paid to details of the visceral structure. TCM has explored and amassed an entire system of knowledge that has not yet been fully recognized or accepted by CWM.
TCM, a cultural treasure founded by ancient Chinese philosophers and doctors, has served human health for thousands of years. Unfortunately, for some understood reason, about 1000 years ago TCM almost neglected its precious traditional meditation practice and energy cultivation technique. Today, many TCM doctors do not understand the concept of invisible matterand would have difficulty fully comprehending some of the contents of this chapter. Some may even try to “correct” TCM theory based on CWM anatomy. Nonetheless, descriptions of visceral structures in TCM remain based on the intangible, in addition to the solid body. With this background information and an open-minded attitude, we may overcome cultural and historical differences, and better comprehend this chapter. For example, TCM has noted that obsessing or over-thinking often results in indigestion or loss of appetite. Since food digestion and absorption is governed by Piviscera (closely related to the Spleen–Pancreas system with its aura and meridian), according to TCM’s exploration of the relationship between consciousness and the viscera, “thinking” is dominated by Pi.
Zang Xiangtheory considers physiological functions, pathological visceral changes, and inter-body relationships. The last include relationships between the five Zang-viscera, the six Fu-viscera, the six groups of meridians, the five constituents (vessels, tendons, muscles, skin, and bones), the five sensory organs (eyes, ears, nose, tongue, and body), the nine orifices (eyes, mouth, nose, ears, external genitals, and anus), and the extraordinary Fu-viscera (Brain, Marrow, Bone, Blood vessels, Gall Bladder, and Uterus).
The Basic Questionssays, “The five Zang-viscera store but do not discharge essential Qi. So, they do not hold food or waste but can be full of Essential Qi”; “The six Fu-viscera do not store but transport and transform the food. So, they do not store Essential Qibut can be full of food and water” . The six Fu-viscera are luminal organs which “transport and transform food,” or receive and digest food and water, and transport and discharge waste.
Essential Qimay exist in the six Fu-viscera for transport to and storage in the five Zang-viscera; used, turbid Qimay exist in the five Zang-viscera for transport to and excretion from the six Fu-viscera.
The extraordinary Fu-viscera are mostly hollow, like the six Fu-viscera, hence their name; but they store Essential Qi, like the five Zang-viscera. TCM says, “The chest looks like a thin fog, the upper abdomen like a pulp-filled cauldron and the Lower abdomen like streams.”
Based on the theory that “viscera are located in the interior, but their state can be reflected externally,” ancient medical experts made careful, lengthy observations and studied the internal and external manifestations of the viscera’s physiological and pathological activities. They gradually accumulated the laws of visceral activities.
Over 2000 years ago, Chinese doctors were clearly familiar with basic anatomy, as recorded in The Inner Canon of the Yellow Emperorand The Classic of Difficulties; but TCM continues to focus on the more difficult invisible system to perceive holistic manifestations of functions and to distinguish between the intrinsic manifestations and the external manifestations.
Zang Xiangtheory says that Qi, Blood, Yin, and Yang are the essential substances which constitute and maintain the physiological functions of the Zang–Fuorgans. It focuses on physiological functions and pathological changes in the Zang–Fuorgans, somatic tissues, both tangible and intangible elements, and the mutual relationships among them. Zang Xiangtheory is the core of TCM’s theoretical system. Despite some identical CWM terminology, the very different physiological functions of Zang–Fuorgans are based on Zang Xiangtheory imbued with oriental philosophy, keen observation, exploration of human potential, and clinical practice. Zang Xiangknowledge reaches beyond CWM’s anatomy and physiology, with its view of the body and its Spirit 
or normally invisible matter. For example, the Spirit 
resides in the Heart, the Corporeal Soul 
in the Lung, the Ethereal Soul 
in the Liver, Thought 
in the Spleen, and Willpower 
is found in the Kidney. The five souls are all invisible matter of Essence, each possessing an energy and message, but they have different characteristics and functions not considered within the paradigm of CWM knowledge.
Based on ancient Oriental philosophy, some TCM principles are not easily understood. Hence, some phenomena or conclusions developed in TCM have not been explained or proven by traditional sciences. However, Quantum Mechanics in the 20th century helps us understand more about it.
As described by quantum equations, “the wave–particle Essence” is expressed as a wave–particle function and substantiates that matter is both solid and invisible (or Yin and Yang). “Quantum entanglement” substantiates the complete holistic aspects of the system. “Quantum uncertainty” introduces the influence of the human’s consciousness and mind 
which have been considered outside the traditional scientific realm.
In CWM’s view, the viscus is an individual organ, but in TCM every viscus is inseparable from the system, which includes several Yin–Yang meridians and viscera as a union. One of the TCM Zang Xiangmodels, called “Six-meridian Zang XiangSystem Theory,” is classified mainly by meridian. It is very useful for the complicated medical situation, as follows:
| (1) | Taiyang meridian–Zang Xiang system: including hand Taiyang, foot Taiyangwith hand ShaoyinMeridians and connected Heart, Brain, Small Intestine, Bladder, blood vessel, tongue as a gather-up system. |
| (2) | Yangmingmeridian–Zang Xiangsystem: including hand Yangming, foot Yangmingwith hand TaiyinMeridians and connected Lung, Large Intestine, Stomach, skin and hair, nose as a gather-up system. |
| (3) | Shaoyangmeridian–Zang Xiangsystem: including hand Shaoyang, foot Shaoyangwith hand JueyinMeridians and connected Gall Bladder, San Jiao, Pericardium, Subcutaneous tissue, larynx as a gather-up system. |
| (4) | Taiyinmeridian–Zang Xiangsystem: including hand Taiyin, foot Taiyinwith foot YangmingMeridians and connected Spleen, Stomach, Lung, four limbs, muscle, and lips as a gather-up system. |
| (5) | Shaoyinmeridian–Zang Xiangsystem: including hand Shaoyin, foot Shaoyinwith foot TaiyangMeridians and connected Kidney, Heart, Bladder, skeleton, ears as a gather-up system. |
| (6) | Jueyinmeridian–Zang Xiangsystem: including hand Jueyin, foot Jueyinwith foot ShaoyangMeridians and connected Liver, Gall Bladder, Pericardium, tendons, and so on as a gather-up system. |
To avoid confusion, Chinese names are used for Zang–Fuorgans. “Viscera” here refers to both the flesh (anatomy) and the intangible (invisible Qi, aura, and meridian connections with other organs) aspects of organs. So, “Heart” (Xin, 
) in TCM is not equal to “heart” in CWM.