There are Governor Vessel(督脈), Conception Vessel(任脈), Thoroughfare Vessel(衝脈), Belt Vessel(帶脈), YIN Heel Vessel(陰蹻脈), Yang Heel Vessel(陽蹻脈), Yin Link Vessel(陰維脈) and Yang Link Vessel(陽維脈) in the category of the Eight Extra Channels. They keep the equilibrium state by controlling the unbalance between qi and blood(氣血), Yin and Yang(陰陽), and irrigate the Twelve Regular meridians(十二經脈). They are independent of the Twelve Regular meridians(channels) in running(流注), and, therefore, have their own running, and symptoms of disease. We have bibliographically studied the running, cross points, and symptoms of the Eight Extra meridians, and described the results as figures. By this study, we could confirm that the Eight Extra meridians have their own running, and symptoms of disease. We'll have to study further the application of this conclusion and the correlation between the Extra meridians(奇經) and the Regular meridians(正經).

We investigated skin thermal changes after acupuncture stimulation for Meridian mechanism. So non-acupuncture group, acupuncture at left LI4 and acupuncture at left, right acupuncture group were observated in 0 min, 5 min and 10 min. And results was acupuncture group of left LI4 was increased in 0 min, 5 min and 10 min significantly. We proposed that increasing thermal changes was caused by Meridan and Gi reaction.