The tongue is the seedling of the heart, and the heart meridian of the hand is not tied with the tongue. The heart governs the blood vessels, and at the same time, we observe that there are many meridians under the tongue, so the blood born from the heart can also reach the tongue and be expressed from the color of the tongue. The meridians of the lung can also reach the throat and connect with the root of the tongue. The spleen meridian with insufficient yin can communicate with the tongue and disperse under the tongue, so how a person's appetite and taste reflect the state of spleen's transport and transformation function in the body. Moreover, Chinese medicine also says that tongue coating is caused by stomach qi steaming, which is manifested on the tongue surface, and spleen is closely related to clearing stomach and reducing turbidity. The so-called stomach disease is inseparable from the spleen. The liver meridian of Foot Jueyin also collaterals the tongue, and the function of the liver is to store blood, which can avoid tongue bleeding and regulate blood. The kidney meridian of foot shaoyin is the tongue-clamping meridian. It can be seen that the tongue is closely related to the five internal organs.
Many doctors have their own distribution of tongue and viscera, but several of them are recognized.
Firstly, it is divided into five internal organs: the tip of the tongue belongs to the heart and lung, the side of the tongue belongs to the liver and gallbladder, the tongue belongs to the spleen and stomach, and the root of the tongue belongs to the kidney. From this distribution, we can also see that the theory of Yin-Yang and Five Elements in TCM is widely used as a basic theory. Judging the condition of gastropathy can also be divided into stomach meridians: the tip of the tongue is the upper abdomen, the middle abdomen and the base of the tongue is the lower abdomen, but compared with the former, this one is only used for gastropathy and its application scope is relatively narrow. According to Sanjiao's words: the tip of the tongue becomes the upper and middle focus in the tongue, and the base of the tongue becomes the lower focus, which is also limited for febrile diseases.
Many tongue diagnoses still play a very prominent role in the diagnosis of diseases to a great extent, which can explain that the five internal organs have certain changes on the tongue and have certain reference value. But we should not be too persistent. Times are changing and methods are different. A better diagnosis requires a comprehensive analysis of the four diagnoses and other diagnoses.