The tendons are the tissues that connect the muscles, the skeleton and the joints. The contraction and relaxation of the tendons maintain the flexion and extension or lateral rotation of the joints.The liver governing the tendons means that the physiological functions of the tendons depend on liver-blood to nourish and liver-yin to moisten. Only when liver-yin and liver-blood are sufficient can the tendons get enough nourishment and the joints move flexibly and powerfully. If liver-yin and liver-blood are deficient, the tendons cannot get enough nourishment, leading to unsmooth movement of the joints, tremor of hands and feet, numbness of the limbs or susceptibility to fatigue.

     

The liver meridian runs upward into the eyes. So the eyes are nourished by liver-yin and liver-blood. Besides, the liver can regulate the activities of the eyes with its dredging and regulating functions. Thus eyesight is closely related to the liver. The conditions of the liver can be observed from the manifestations of the eyes. That is why it is said that "the liver opens into the eyes". For example, insufficiency of liver-yin and liver-blood may lead to dryness of the eyes and blurred vision; failure of the liver to dredge and regulate may lead to up-flaming of liver-fire, consequently bringing on redness, swelling and pain of the eyes and cataract.

Besides, the essence of the five zang-organs and six fu-organs all flows into the eyes. So the eyes are not only related to the liver, but also to the other viscera. For example, the white part of the eyes pertains to the lung that governs qi, so it is termed qi-wheel; the black part of the eyes pertains to the liver that governs wind, so it is termed wind-wheel; the internal and external canthi pertain to the heart that governs blood, so they are termed blood-wheel; the upper and lower eyelids pertain to the spleen, so they are termed muscle-wheels; the pupil pertains to the kidney that governs water, so it is termed water-wheel. Altogether they are called "five wheels".

     

Manifestation on the Nails   

The nails here include both the nails of fingers and toes. TCM believes that the nails are the extensions of the tendons. The nails, like the tendons, depend on liver-blood to nourish. Thus deficiency of liver-blood often affects the color and quality of the nails. For example, if liver-blood is sufficient, the nails are firm and bright, ruddy and lustrous; if liver-blood is insufficient, the nails are soft and thin, or even deformed or brittle.