Skin layers

Ancient Chinese medicine had its own conception of the skin as made up of different layers and muscles. This conception was similar to that of modern Western medicine. The various layers and muscles in the structure of the skin are:

Fu indicates the superficial layer of skin (i.e. the epidermis), which is influenced mostly by the Lungs. Ge indicates the deep layer of skin (i.e. the dermis), which is influenced by the Lungs, Liver and Kidneys. Ji, a word that is sometimes translated as “flesh”, indicates the subcutaneous muscles and this structure is influenced by the Spleen and Liver. Fen Rou indicates two structures, i.e. fat (influenced by the Spleen, Kidneys and Directing Vessel) and muscles near the bones (influenced by the Spleen and Liver). Cou Li (therefore, the space between skin and muscles) is influenced by the Lungs and Spleen.¹ Xuan Fu are the pores (including the sebaceous glands) through which the sweat comes out and they are influenced by the Lungs and Spleen.

Box 21.1 summarizes the organs influencing each layer of the skin.

Types of skin lesion

Figure 21.1 shows the various types of skin lesions.

The skin and the Lungs

As a whole, the skin is influenced by the Lungs. Chapter 10 of the “Simple Questions” says: “The Lungs are connected to the skin and control the state of the body hair”.² The Lungs also control the opening and closing of the pores and this function is related to the Lung’s diffusing of Defensive Qi to the skin. The pores were called “sweat holes” (Han Kong) and their function is to discharge turbid Qi and sweat. The Defensive Qi and, therefore, the Lung’s opening and closing of the pores, is a manifestation of the protective function of the Defensive Qi against the invasion of pathogenic factors. When the Defensive Qi is properly regulated, the pores are closed on exposure to a pathogenic factor and properly open during exercise or on exposure to hot weather. A weakness of Lung-Qi and of the Defensive Qi may lead to “flaccidity” of the pores and result in their being too open: this facilitates the invasion of pathogenic factors. In pathology, a weakness of Lung-Qi, and therefore of the Defensive Qi in the space between the skin and muscles, causes acute skin diseases due to invasion of external Wind such as urticaria.

The skin and the Stomach and Spleen

The Stomach and Spleen produce Qi and Blood and the turbid part of Qi forms the Defensive Qi while the clear part forms Nutritive Qi. The Defensive Qi, through the diffusing of Lung-Qi, reaches the skin, warming it and regulating the opening and closing of the pores. On the other hand, the Stomach fluids also reach the skin through the diffusing of Lung-Qi, moistening it. The Stomach is also one of the origins of Body Fluids, part of which go to the Lungs and part of which go to the Kidneys. Kidney-Yang warms the Body Fluids deriving from the Stomach; the turbid part is excreted as urine and the pure part goes to the skin via the Triple Burner and the Bladder channel in the back.

The Spleen also controls the muscles immediately below the skin as well as the adipose tissue located there. In pathology, a deficiency of the Spleen may affect these structures and cause diseases such as scleroderma. Of course, Dampness resulting from a deficiency of the Spleen is the cause of many common skin diseases such as eczema, herpes, acne, etc. A failure of Spleen-Qi in holding blood in the vessels may cause bleeding under the skin and therefore red maculae.

The skin and the Kidneys

The Kidneys also influence the skin in other ways. First of all, although the Lungs diffuse Defensive Qi, and the Stomach and Spleen contribute to Defensive Qi’s production, the Defensive Qi stems from the Lower Burner and from the Kidneys. Defensive Qi is Yang in nature and it is therefore influenced by Kidney-Yang and the Fire of the Gate of Life. The Kidneys also play an important role in the distribution of Defensive Qi to all other channels and parts of the body with the aid of the Triple Burner and the Bladder channel. The Back Transporting points where the Defensive Qi infuses to the Internal Organs are situated in the back along the Bladder channel. This is because the Defensive Qi emerges from the Kidneys, through the Triple Burner, and flows up along the Bladder channel. Moreover, when the Defensive Qi emerges in the morning after flowing in the Yin organs at night, it starts from the Kidney channel (Chapter 76 of the “Spiritual Axis”)³ (Fig. 21.2).

Therefore, when the Kidneys are deficient, the Defensive Qi may also be deficient. This deficiency in the skin gives rise to skin diseases. In particular, a deficiency of the Kidneys, with its consequent failure to irrigate the skin with Defensive Qi, is often at the root of complex, modern skin diseases such as lupus erythematosus or scleroderma.

Apart from a Kidney deficiency and impairment of the Defensive Qi circulation in the skin, these diseases are often associated with Yin Fire, that is, a pathological rise of the Minister Fire upwards stemming from a deficiency of the Original Qi (Yuan Qi). In such diseases, there are superficial manifestations on the skin but the root cause is a Kidney deficiency and a deficiency of the Original Qi; this also explains the often contradictory signs of a red rash on the skin of the face and a Pale tongue.

The Triple Burner also influences the skin and, in particular, the skin’s moisture, because it plays such an important role in the metabolism of fluids. One important aspect of the Triple Burner, in fact, is the diffusion of fluids in the Upper Burner, the separation and transformation of fluids in the Middle Burner and the excretion of fluids in the Lower Burner. As heat is needed to transform and excrete fluids, the Triple Burner relies on that derived from the Fire of the Gate of Life in between the Kidneys. From this point of view, the Triple Burner’s function of transporting and excreting fluids is inseparable from its location between the Kidneys where the Fire of the Gate of Life resides. For this reason, the Triple Burner is closely related to the Original Qi.

Chapter 66 of the “Classic of Difficulties” states:

As the Original Qi, which resides between the Kidneys, is the basis for the Triple Burner and transforms fluids that affect the skin, this is another way in which the Kidneys influence the skin (Fig. 21.3).

Chapter 47 of the “Spiritual Axis” illustrates the connection between the skin and the Kidneys and Triple Burner: “The Kidneys are connected with the Triple Burner and the Bladder which influence the pores and body hair”.⁶ Another passage from Chapter 64 of the “Simple Questions” also illustrates the relationship between the Kidneys and the skin: “When there is a pathogenic factor in the Kidneys, the skin is affected and there is a rash.”⁷

Therefore, if the Kidneys are healthy, the skin is moistened and has lustre. If the Kidneys are deficient (in particular Kidney-Yin), the fluids are deficient and the skin loses moisture and becomes dry and lustreless. The thickening and hardening of the skin seen in scleroderma may be caused by a deficiency of Kidney-Yin in chronic cases. If Kidney-Yang is deficient, the fluids accumulate in the space between the skin and muscles and cause oedema.

The skin and the Liver

The Liver influences the skin through Liver-Blood. Like Kidney-Yin, Liver-Blood moistens and nourishes the skin and a deficiency of Liver-Blood is a common cause of dry skin, especially in women (of course, Liver-Yin deficiency may also bring this about). Liver-Fire, on the other hand, has a heating effect on the skin and is the underlying pattern in many skin diseases.

The skin and the Heart

The Heart influences the skin in a similar way to the Liver: Heart-Blood moistens and nourishes the skin just as Liver-Blood does. The influence of Heart-Blood in skin diseases, however, is seen especially on the face.

Box 21.2 summarizes the influences of the Internal Organs on the skin.

Thus, from the diagnostic point of view, the skin reflects first of all the state of the Body Fluids, and therefore of the organs mentioned above, and also conditions of Heat or Cold, Fullness or Emptiness and of Yin or Yang.

The skin and the Connecting channels

The blood vessels (venules) visible on the surface of the skin are always a reflection of the Connecting channels. When they become visible, the blood vessels are an expression of the percolation of the Blood Connecting channels towards the surface of the skin (the Blood Connecting vessels at the deep level of the Connecting channels).

Chapter 17 of the “Spiritual Axis” says: “The Main channels are in the Interior, their branches are horizontal [or crosswise] forming the Luo channels: branching out from these are the Minute Luo. When these are Full with stagnant Blood they should be drained with bleeding with needle; when they are deficient, they should be tonified with herbs”.⁸ Chapter 10 of the same book says: “The Main channels are deep and hidden between the muscles and cannot be seen; only the Spleen channel can be seen as it emerges from above the internal malleolus and it has no place to hide. The Luo channels are superficial and can be seen.”⁹ The same chapter also says: “When the Luo channels are greenish-bluish it indicates Cold and pain; when they are red it indicates Heat.”¹⁰

Macules are a reflection of the Blood Connecting channels and red macules indicate Blood-Heat, while purple ones indicate Blood stasis. Bluish macules indicate pain and Blood stasis. Papules indicate Heat in the Connecting channels. Vesicles indicate Dampness in the space between skin and muscles and the Connecting channels. Pustules indicate Toxic Heat in the Connecting channels.

Apart from the blood vessels, the colour of the skin itself reflects the condition of the Connecting channels; red indicates Heat, green indicates pain, purple indicates Blood stasis, and bluish indicates Blood stasis and pain.

Skin colour

“Skin colour” refers to the colour of the body skin itself, as distinct from the complexion (discussed in Chapter 3). It does not refer to skin rashes, which will be discussed separately. The colours discussed are:

Of course, when observing body-skin colour one should take into account individual variations due to race and occupation. This has already been discussed in Chapter 3 dealing with observation of the complexion. For example, a body skin that might be described as “pale” in a Mediterranean person would be normal in a Swedish person. Generally speaking, the colours described below apply to any racial group: for example, the body skin of an African-American or an Indian may be pale in colour, like a Caucasian’s, although it will obviously look different.

The pathological colours described below may not necessarily appear all over the body, but may manifest in various localized places; the location of the pathological colour gives an indication of the organ and channel involved. If a large area is affected, this generally indicates that an organ is involved, whereas if the pathological colour appears along a definite line it indicates that the channel is involved. For example, if the epigastrium is generally very pale, it may indicate a condition of Yang deficiency of the Stomach, whereas if there is a redness appearing along the Lung channel it may indicate Heat in that particular channel rather than in the organ (although it would not exclude Heat in the organ as well).

Skin texture

Apart from the colour, other aspects of the skin should be considered:

Skin of the forearm (inner aspect)

Besides palpation, the skin of the inner aspect of the forearm should be observed for slackness, tightness, moistness, dryness, protrusion and shrinking.

If the inner aspect of the forearm looks slack and loose, this indicates Heat; if it is tight, it indicates Cold. If the forearm is moist, this indicates Wind invasion; if it is dry it indicates Blood or Yin deficiency. If the forearm skin seems to be protruding and sticking out it indicates a Full condition; if it looks shrinking and withered, it indicates an Empty condition.

Palpation of the forearm is discussed in Chapter 51.

The space between skin and muscles (Cou Li)

The space between the skin and muscles, called Cou Li, is where the Defensive Qi flows and where sweat comes from.¹¹ The state of the space can be deduced by observing the state of the pores, sweat and skin texture. One should differentiate between a state of openness or closure and one of looseness or tightness.

The state of openness or closure of the space between the skin and the muscles can be judged by the sweating: the presence of sweating indicates that the space between the skin and muscles is open (either through Heat or Yang deficiency); its absence indicates that the space is closed.

A state of excessive openness of the space between skin and muscles facilitates the invasion of external pathogenic factors, while a state of excessive closure renders the person prone to fever and generally Heat.

If the skin is tight and thick, it indicates that the space between skin and muscles is tight, which is caused by a Full condition of the Triple Burner and Bladder; if the skin is loose and thin, it indicates that the space between the skin and muscles is loose, which is caused by an Empty condition of the Triple Burner and Bladder.

Body hair

The body hair indicates the state of the Lungs. One should examine its moistness, lustre and integrity.

If the body hair is lustrous, this indicates good Lung-Qi; if it is not, it indicates weak Lung-Qi. If the body hair is strong and long, this indicates good Qi and Blood; if it is short and weak, it indicates deficiency of Qi and Blood. If the body hair is brittle and breaks easily, this indicates weak Lung-Qi.

If the body hair stands on end, this indicates an invasion of Wind-Cold. If the body hair falls off, it indicates Lung-Heat or Lung-Qi deficiency.

Macules, papules, vesicles and pustules