Section 1　Overview of the Tongue Examination

Tongue examination, also called inspection of the tongue, is a diagnostic method carried out through observing the tongue manifestation. Tongue manifestation refers to the outer signs of the tongue body and tongue coating. The tongue body is composed of muscle and vessels, which are nourished by the qi and blood of thezang-fu organs. The tongue coating refers to the lichen-like material formed on the surface of the tongue. Chinese medicine believes that tongue coating is created from the rising and evaporation of the stomach qi.

Principles of the Tongue Examination

1. The Relationship Between the Structure of the Tongue and Tongue Manifestation

The tongue is a muscular organ consisting of voluntary muscles. The muscles in the body of the tongue work in all three axes i.e. front to back, side-to-side and top to bottom. In addition, other muscles attach the tongue. This complex muscular structure is what gives the tongue its flexibility and the agility needed for eating and speaking. Plenty of blood vessels and ample blood supply among the muscle bundles give the tongue its light red colour and its brightness. Cast-off cells, food debris, bacteria and mucus fill the gaps and form white moss, which is called the tongue coating.

The top side of the tongue is called the lingual surface or dorsum and the underneath is called the undersurface. The lingual surface of the tongue is covered with a layer of semitransparent mucous membrane and many papillae. According to their different shapes, these papillae are divided into filiform papillae, fungiform papillae, circumvallate papillae and foliate papillae. Filiform papillae and fungiform papillae are closely related to the form of tongue manifestation, circumvallate papillae and foliate papillae are related to the taste sense.

Filiform papillae are conical milky white, soft projections, their height is about 0.5~2.5 mm and they look like fine threads or when magnified like small tree stumps. Fungiform papillae are few in number. Fungiform papillae are mostly seen on the tip of the tongue and scattered between the filiform papillae; they appear mushroom shaped.

2. The Relationships Between the Forming of the Tongue Manifestation and theZang-fu Organs, Channels and Collaterals

(1) The five zang organs and six fu organs are related to the tongue through the channels and collaterals

Heart —— The tongue is the sprout of the heart, the collateral of the heart channel of the handshaoyin flows to the root of the tongue.

Spleen —— The tongue is the external sign of the spleen, and the spleen channel of the foottaiyin connects with the root of the tongue and scatters across the undersurface.

Liver —— The liver channel of the footjueyin has a network of vessels in the tongue root.

Kidney —— The kidney channel of the footshaoyin anchors the tongue root.

Otherzang-fu organs are also related directly or indirectly to the tongue via channels and collaterals. Through inspection of the tongue, the practitioner can understand both the condition of health as well as exuberance and debilitation of thezang-fu organs or channels and collaterals.

(2) The relationships between the tongue and heart, spleen and stomach

Amongst the fivezang organs and sixfu organs, the relationships between the tongue and the heart, spleen, and stomach are the most intimate. As previously stated, the tongue is the sprout (sometimes called the mirror) of the heart, the external sign of the spleen, and the tongue coating is created from the rising and evaporation of the stomach qi.

In addition, there are plenty of vessels in the tongue and this has a relationship with the heart governing the blood and vessels. Active moving of the tongue can adjust the voice and produces speech and this is related to the heart governing the mind. Consequently, the tongue manifestation can reflect the functional status of the heart. Furthermore, the heart is the great governor of the fivezang and sixfu organs. Accordingly, the functional status of the heart can reflect the functional status of all thezang-fu organs, qi and blood. Therefore, diseases of thezang-fu organs or qi and blood can be reflected on the tongue through the heart functions.

The taste sense of the tongue can influence the appetite, as it is related to the spleen governing transportation and transformation, and with the stomach governing reception. The spleen and stomach are the foundation of acquired constitution and the source of qi and blood production. Thus, tongue manifestation also reflects exuberance and debilitation of the qi, blood and fluids all over the body.

(3) The relationships between the tongue manifestation and qi, blood and fluids

The shape, texture and colour of the tongue are concerned with exuberance, debilitation and movement of the qi and blood. A moist or dry tongue body and tongue coating are related to the amount or loss of fluids. Body fluids and their generation, transfusion and distribution are closely related to thezang-fu organs, such as the kidneys, spleen and stomach, e.g. saliva is the fluid of the kidneys, drool is the fluid of the spleen, they are all types of body fluids. For this reason, inspections of the colour, shape, motility, moistness or dryness of the tongue body and tongue coating are helpful for judging the exuberance or debilitation of qi, blood and body fluids.

(4) The individual reflections of the zang-fu organs on the tongue

The tongue manifestation reflects whole body pathological changes, and there are also symbolic regions on the surface of the tongue, which reflect particularzang-fu organs.

• The tip of the tongue reflects the pathological changes of the heart and lung.

• The centre of the tongue reflects the pathological changes of the spleen and stomach.

• The margins of the tongue reflect the pathological changes of the liver and gallbladder.

• The root of the tongue reflects the pathological changes of the kidneys.

Another division: the tip of the tongue can be ascribed to the upper-third portion of the stomach cavity, whilst the centre of the tongue can be ascribed to the middle-third portion of the stomach cavity, and the root of the tongue can be ascribed to the lower-third portion of the stomach cavity.

Method of the Tongue Examination

1. Posture/Position

The patient should be sitting or lying back in a comfortable position, facing the natural light, asked to open the mouth as far as possible, extend the tongue naturally and let it be exposed thoroughly. The tongue body should now be relaxed, unfolded and sufficiently exposed; the tip of the tongue should point downwards.

Note: Excessive tension, curling of the tongue body, only the tip exposed, or extending it out for a long-time, can all affect the validity of the tongue manifestation. The inspection should be rapid, if the practitioner fails to make an assessment, they can repeat the inspection after the patient has rested.

2. Body Position

The practitioner should be facing the patient looking straight at them and observe the tongue from above.

3. Sequence

First, examine the colour and lustre, spots, thickness or thinness, roughness or tenderness and dynamic state of the tongue body. Second, observe the condition of the tongue coating, such as thickness, curd-like or greasy, colour, moistness or dryness. Third, observe from the perspective of the location of the tongue coating, this is whether it can be seen from the tip of the tongue to the centre, on the margins of the tongue, or on the root of the tongue.

4. Scraping the Tongue

By using the border of a disposable tongue depressor with moderate strength, the practitioner should scrape from the root to the tip of the tongue, three to five times. If the tongue coating cannot be scraped, or a dirty coat remains after scraping, this is due to an interior excessive pathogen. If the tongue coating can be scraped easily, this indicates that a deficiency pattern is present.

5. Wiping the Tongue

By winding sterile absorbent gauze around the forefinger and dipping it in mild sodium chloride, the practitioner should wipe the tongue surface several times.

Scraping the tongue and wiping the tongue can both be used to distinguish if the tongue coating has a root or is rootless, or if it is a stained coating that is being observed.

Summary of the Important Parts of the Tongue Examination

1. Light

It is essential to have sufficient and soft natural light.

2. Stained Coating

Drinking and eating often changes the shape and colour of the tongue coating. For example, some foods or medicines can colour the tongue coating; this is called a stained coating. Thus, when inspecting the abnormal colour of the tongue coating, the practitioner should remember to ask the patient about recent eating habits, prior to their visit.

3. Oral Cavity

Injured, damaged or infected teeth can make the tongue coating on that side increase in thickness. Mounting an artificial tooth can make an indentation on the margin of the tongue body. Open mouth breathing can dry and thicken the tongue coating. All of these factors can produce an abnormal tongue manifestation. However, they are not pathological changes of the body, and should be paid attention to and correctly identified.