There are two basic functions of the meridians and collaterals. One is to connect the external with the internal as well as to connect the viscera with other organs. The other is to transport qi, blood, yin and yang to nourish the viscera and the body. In physiology, pathology and treatment, the meridians and the collaterals are responsible for the transmission and conduction of physiological
and pathological information as well as the regulation of the physiological functions of the body.

To connect the external with the internal as well as to connect the viscera with other organs
The body is an organic whole. It is the meridians and collaterals that connect the viscera, the body, the five sensory organs and the nine orifices together. The meridians internally pertain to the viscera and externally connect the limbs. Since the meridians are composed of various collaterals of different levels, they have formulated the whole body into a network. There are three basic ways with which the meridians to connect all parts of the body together.

The relationships between the viscera, the body, the sensory organs and the orifices
The connection between the external and the internal as well as the viscera and other organs is mainly accomplished by the twelve meridians. On the one hand the twelve meridians and their branches accomplish such a connection by emerging from the external of the body and entering the internal of the body. On the other hand, they reinforce such a connection with the twelve branches, twelve tendons and twelve skin divisions.v