The cutaneous regions are the sites where Qi of collaterals spreads. In this article

the exterior-interior relationship between cutaneous regions and collaterals and their physiological functions and pathological states were excavated and analyzed

based on their name paraphrasing

locations and constructions researches. The cutaneous collaterals theory is an important part of traditional Chinese medicine（ TCM） theories and plays an important role in the diagnosis and treatment system of TCM

especially in the observation diagnosis. All the Qi and blood in twelve meridians are gathering upward to face

so observing facial cutaneous collaterals could help make diagnosis and treatment. Also

by watching the fingerprint collateral of a young child

the relevant internal organic lesions and disease characters of cold-heat and deficiency-excess were judged by its length

color and lustre changes. Besides

the transfer approach of Chinese external medicines was explained on the cutaneous collaterals theory which might establish the transport mechanism theoretical basis of transdermal drug delivery of external therapy of TCM.