The body of the tongue is in close relation with the visceral qi and blood through meridians. By means of inspection, one can understand the conditions of the viscera, qi and blood. Inspection of the body of the tongue includes the color, shape and movement of the tongue.

1. Color of the tongue
It includes the four changes as follows:

(1) Light-reddish tongue:
The tongue is light-reddish, moist and lustrous. Such a condition of the tongue is usually seen among healthy people, suggesting sufficiency of qi and blood. Sometime it is also seen in mild cases, such as primary stage of exogenous disease, mild pathological conditions, or mild internal impairment, indicating that qi, blood, yin, yang and viscera are not involved.

(2) Light-whitish tongue:
The color of the tongue is lighter than that in normal condition, more white and less red, or even showing no signs of blood. Such a condition suggests deficiency of qi and blood or asthenia of yangqi.

Malnutrition of the tongue due to asthenia of qi and blood. The tongue is light-white due to asthenia of qi and blood or asthenia of yangqi which fails to transport blood to nourish the tongue. For example, light-white and thin tongue is due to deficiency of qi and blood; light-white and bulgy tongue is due to asthenia of yangqi.

(3) Rod and deep-rod tongue:
The tongue is redder than that in the usual condition. The deep or dull red tongue is called deep-red tongue. Red and deep-red tongue both indicates heat syndrome. The redder the tongue is, the severer the heat.

Red or deep-red tongue is caused by superabundance of blood in the vessels of the tongue due to hyperactivity of the tongue. Slightly red tongue or reddish margins and tip of the tongue indicates exogenous superficial heat syndrome; reddish tongue tip indicates up-flaming of heart fire; deep-red tongue with fur indicates sthenia-heat syndrome frequently seen at the superabundant heat stage of exogenous disease, or in relative predominant visceral heat in miscellaneous diseases due to internal impairment; deep-red tongue with scanty fur or without fur indicates asthenia-heat syndrome seen at the advanced stage of exogenous febrile disease with consumption of yin fluid or in patients with yin asthenia and superabundance of fire due to internal impairment and chronic disease.

(4) Cyanotic and purplish tongue:
The tongue is completely cyanotic or purplish, or cyanotic and purplish or purplish macules on the surface of the tongue, indicating inhibited circulation of qi and blood.

Cyanotic and purplish tongue is caused either by internal exuberance of yin cold and obstruction of vessels or by superabundance of pathogenic heat and obstruction of vessels; or by decline of yangqi, weak transportation of blood and inhibited flow of blood; or by failure of the liver to disperse and convey as well as qi stagnation and blood stasis. Light-purplish or dull purplish tongue with moisture is caused by inhibited flow of qi and blood due to yang asthenia and yin exuberance; purplish red or deep-purplish and dry tongue is caused by superabundant heat consuming fluid and stagnation of qi and blood; dull purplish tongue or tongue with purplish macules is caused by internal retention of blood stasis. Besides, cyanotic and purplish tongue is also seen in cases of congenital heart disease or intoxication by drugs or food.