Principles of Tongue Diagnosis in Traditional Chinese Medicine – Zang-Fu Organs and Meridians are Connected to the Tongue

The tongue is primarily connected to the Zang-Fu organs through meridians. Among the Zang-Fu organs, the Heart and the Spleen-Stomach have the closest relationship with the tongue.

The tongue is the sprout and orifice of the Heart, and a collateral branch of the Hand Shao Yin Heart Meridian connects to the root of the tongue.

《Lingshu·Maidu》 (Miraculous Pivot – Pulse Measurement) states: “The Qi of the Heart communicates with the tongue; when the Heart is harmonious, the tongue can discern the five tastes.” Because the Heart governs the blood vessels, and the tongue has a rich network of vessels, with the Heart’s blood ascending to nourish the tongue, the body’s Qi and blood circulation can be reflected in the color of the tongue body. The Heart governs the mind, and the movement of the tongue body is also controlled by the mind; therefore, whether the tongue moves flexibly and freely, and whether speech is clear, is closely related to mental state. Thus, the tongue can reflect pathological changes of the Heart and the mind.

The tongue is the external manifestation of the Spleen. The Foot Taiyin Spleen Meridian connects to the root of the tongue and disperses beneath it, and the tongue is located in the mouth, governing the sense of taste. 《Lingshu·Maidu》 (Miraculous Pivot – Pulse Measurement) states: “The Qi of the Spleen communicates with the mouth; when the Spleen is harmonious, the mouth can discern the five grains.” Hence, it is said that the Spleen opens into the mouth. Traditional Chinese Medicine believes that the tongue coating is formed by the Stomach Qi steaming upwards with the grain Qi reaching the tongue surface, corresponding to the Spleen and Stomach’s function of transportation and transformation. As Zhang Xugu said: “The Spleen and Stomach are the central earth; when evil enters the Stomach, a coating is produced, just as grass grows on the ground.” The tongue body relies on the nourishment of Qi and blood, so the tongue appearance can reflect the state of abundance or deficiency of Qi and blood, which is directly related to the Spleen’s function of governing transportation and transformation and generating Qi and blood.

Furthermore, the Liver stores blood and governs the sinews, and the Foot Jue Yin Liver Meridian connects to the root of the tongue; the Kidneys store essence, and the Foot Shao Yin Kidney Meridian follows the throat and flanks the root of the tongue; the sinews of the Foot Tai Yang Bladder Meridian connect at the root of the tongue; the Lung system reaches upwards to the throat and connects with the root of the tongue.

Other Zang-Fu organs and tissues, connected by meridians, also have direct or indirect relationships with the tongue. Therefore, once pathological changes occur in the Zang-Fu organs, corresponding changes will also appear in the tongue appearance. Thus, the tongue can serve as a window for observing the state of abundance or deficiency and changes in Qi and blood of the internal Zang-Fu organs.

— Excerpt from Li Candong’s Diagnostics of Traditional Chinese Medicine

Heart: The tongue is the sprout of the Heart; the Hand Shao Yin Heart Meridian connects to the tongue (Lingshu·Maidu: ‘When the Heart’s Qi is harmonious, the tongue can distinguish the five tastes’).

Spleen and Stomach: The Foot Taiyin Spleen Meridian communicates with the underside of the tongue; the tongue coating is formed by the Stomach Qi steaming upwards with the grain Qi (Zhang Xugu: ‘Stomach generates coating like grass grows on the earth’).

Liver: The Foot Jueyin Liver Meridian networks the root of the tongue.

Kidneys: The Foot Shaoyin Kidney Meridian flanks the root of the tongue.

Bladder: The sinews of the Foot Taiyang Meridian bind at the root of the tongue.

Lungs: The Lung system connects to the root of the tongue.

The Heart governs the blood vessels → The color of the tongue body reflects the state of Qi and blood.

The Heart governs the mind → The movement of the tongue is related to mental state (clarity of speech indicates the state of the mind).

The Spleen governs transportation and transformation → The tongue appearance reflects the state of Qi and blood (abundance or deficiency).

Upward ascent of Stomach Qi → The tongue coating reflects the state of digestion.

Window to Zang-Fu Organ Pathology: The tongue appearance changes with the state of Qi and blood in the Zang-Fu organs, especially the Heart, Spleen, and Stomach.

Key Observation Points:

• Tongue Body: Color (e.g., red and deep red indicates Heart fire).
• Tongue Coating: Thickness/moistness (indicates Spleen and Stomach function).
• Tongue Posture/Movement: Flexibility (indicates the state of the mind/Shen).