Exterior and interior

The outer part of the body and the inner part of the body; two of the eight principles. The skin and the body hair, the flesh, and the superficial channels are exterior. The bone marrow, the bowels and viscera, etc., are considered as interior.

Exterior and interior are two of eight principles of pattern identification, by which the depth of penetration of external evils is determined. External evils usually pass through the exterior before penetrating the interior; hence their presence makes exterior-interior pattern identification a necessity. Internal damage miscellaneous diseases originate within the body and invariably manifest as interior patterns so that the need for exterior-interior pattern identification is of little significance.

In the cold damage and warm disease theories, exterior and interior have specific definitions. In cold damage, there are two definitions: a) the yáng channels are exterior and the yīn channels are interior, b) among the yáng channels, greater yáng (tài yáng) is exterior, whereas yáng brightness (yáng míng) is interior, with lesser yáng (shào yáng) as half exterior half interior. In warm disease triple burner pattern identification, the upper burner is exterior, whereas the middle and lower burners are interior.