The skin areas, the regions where the twelve meridians distribute on the skin, are the regions where the meridian qi effuse over the skin and the functional activities of the twelve meridians are reflected on the body surface.
The distribution of the skin areas follows the distribution of the twelve meridians on the body surface.
The skin areas govern closure and opening and are the pivot responsible for the association of the body with the nature. The skin areas regulate the closing and opening states of the muscular interstices and the functions of the viscera in response to the outward stimulation so as to enable the body to be in harmony with the nature. Such a function is closely related to the functions of defensive qi and the lung. That is why skin areas are regarded as the defensive screen of the body.
Under pathological conditions, the skin areas may act as the routes to transmit pathogenic factors inside and reflect the pathological conditions of the viscera and meridians. Clinical diagnosis and treatment of disease according to the examination of the external manifestations is actually done in light of the theory of skin areas.