Tongue inspection, also called tongue diagnosis, includes inspection of the size, shape, color and the moisture of the tongue and its coating as well as the movement of the tongue.

Tongue inspection is one of the most special diagnostic methods in TCM. Clinical practice has proved that tongue inspection has high value in identification of patterns and treatments.

Margins of the tongue* refer to the two lateral* borders of the tongue, and root of the tongue refers to the part of the tongue that attaches basally to the bone.

Fig. 6-2 Correspondence of viscera and bowels on the tongue

Viscera and bowels correspond to the specific areas of the tongue as illustrated in Fig. 6-2. The heart and the lungs correspond to the tip. The center of the tongue corresponds to the spleen and stomach. The root of the tongue corresponds to the kidneys and bladder. And the margins of the tongue correspond to the liver and gallbladder. Diseases of viscera and bowels often reflect on their corresponding tongue regions. However, manifestations on the tongue in clinical practice need to be analyzed together with all other symptoms and signs.

A tongue of normal color is a pale red tongue*. This color of tongue is usually seen among healthy people, suggesting sufficiency of qi and blood and normal function of the viscera and bowels. When this tongue appears in the course of a disease, it usually indicates that qi and blood, yin and yang, and viscera and bowels have not been damaged. Pale tongue* is less red than normal, indicating qi and blood deficiency or presence of deficiency-cold.

Red tongue* is redder than normal, indicating presence of heat, either excess or deficiency. Red at the tip of the tongue usually indicates heart fire flaming upward; red on both margins of the tongue mostly denotes heat in the liver meridian. A red thick tongue mostly indicates excessive heat pattern. A red thin tongue, or with fissure, or with less tongue fur*, or without tongue fur indicates deficiency heat pattern.

Crimson tongue* is a deep red in color, indicating intense heat, or yin deficiency with effulgent fire. Crimson tongue is usually developed from red tongue. Red and crimson tongues both indicate heat pattern. The darker the red tongue becomes, the more severe the heat is. Crimson color is caused by intense heat consuming yin fluid and thickening the blood, or caused by severe yin deficiency with exuberant fire.

Blue tongue* is of bluish color, indicating congealing cold and static blood. Cold congeals and makes the blood static, and static blood leads to less oxygen in the blood, giving rise to a blue color to the tongue.

Purple tongue* is purple in color, indicating stagnant circulation of qi and blood. Purple color of the whole tongue suggests stagnant circulation of qi and blood in the whole body; purple spots on the tongue indicate localized qi and blood stagnation, or localized collateral vessel damage.

Bluish purple tongue* is cyanotic*, indicating blood stasis or heat toxin in the nutrient blood. Bluish purple tongue caused by heat toxin usually is large and dry, maybe with fissures or with thorn*-like protrusions on its surface. Bluish purple tongue caused by blood stasis is usually dark, with petechia*; the patient often has a dry mouth but does not like to swallow water (only gargles).

A luxuriant* tongue is moist, pale red in color and energetic, indicating normal function of qi, blood and body fluid, as well as normal function of viscera and bowels. A withered tongue* is dull, dark, dry and shriveled, usually indicating body fluids having been damaged. A tough* tongue is firm, usually dark, with rough texture, mostly indicating excess pattern. A tender-soft tongue* is delicate, tender-soft, usually large with fine texture, mostly indicating deficiency pattern.

Enlarged tongue* is larger than normal, pale in color and delicate, usually bearing dental indentation* on the margins, mostly indicating water dampness retention, or phlegm dampness heat. Pale enlarged tongue is mostly due to deficiency of spleen and kidney yang failing to transform and transport body fluid. Red enlarged tongue is usually due to dampness-heat in the spleen and stomach.

Swollen tongue* is a large and bulging tongue that makes the mouth full or difficult to open, indicating excess heat or toxicosis. Red swollen tongue usually indicates exuberant heat in the heart and spleen, while purple swollen tongue usually indicates toxicosis.

Thin tongue* refers to one that is thinner than normal, which usually indicates dual deficiency of qi and blood or yin deficiency with effulgent fire. Thin and pale tongue indicates dual deficiency of qi and blood, while thin, red-crimson and dry tongue is mostly observed in yin deficiency with effulgent fire which consumes and damages fluids.

Spotted tongue* has red, white or black spots as well as thorn-like protrusions on its surface, usually indicating exuberant internal heat. Prickly tongue* refers to a tongue with thorn-like protrusions on its surface, suggesting exuberant pathogenic heat in the viscera and bowels or heat invasion into nutrient-blood aspect.

Teeth-marked tongue* has dental indentations on its margins, indicating spleen deficiency and internal retention of water-dampness. Teeth-marked tongue is usually observed together with enlarged tongue. Fissured tongue* has fissures on the surface, usually indicating exuberance of heat, deficiency of fluid or blood, or spleen deficiency with fluid retention.

Red-crimson, dry and fissured tongue suggests exuberant heat consuming fluid and tongue body losing its nourishment. Pale and fissured tongue with scanty fur is usually caused by qi and blood deficiency failing to nourish the tongue body. And large, pale, moist and fissured tongue is usually due to spleen yang deficiency with fluid retention.

The motility of the tongue refers to the ability of the tongue to move spontaneously.

Limp wilting tongue* is flabby and cannot move easily, suggesting yin damage or deficiency of qi and blood. Paralyzed tongue* is numb and unable to move, indicating stroke. Stiff tongue* is a tongue that is stiff, moves sluggishly, and inhibits speech, indicating heat entering the pericardium, or wind-phlegm obstructing collaterals of the tongue. If the tongue suddenly becomes stiff, associated with aphasia*, numbness of the limbs and dizziness, it is a sign of premonitory* of wind stroke.

Deviated tongue* inclines to one side when extended, usually indicating stroke or premonitory of wind stroke. Trembling tongue* refers to a tongue that involuntarily trembles as it moves, indicating internal stirring of liver wind. Protruded agitated tongue* is a pathological condition in which the tongue hangs out of the mouth and moves in a circular motion whereby the tip is extended from and retracted back into the mouth, or licks the lips, usually suggesting heat in the heart and spleen. Contracted tongue* cannot be fully extended from the mouth and appears to be contracted, indicating critical condition. However, congenital lingual frenulum* shortage can limit the tongue from extending out. Protracted tongue refers to one that is habitually extended out of the mouth and cannot be retracted, usually indicating heat-toxin attacking the heart. Protracted tongue* can also be congenital.