经络

The 经络 (jīng luò) — meridians or channels — are the pathways through which qi and blood circulate, connecting the internal organs to the surface and to one another. The twelve regular channels are paired hand/foot and yin/yang, with each channel coupled to a zang or fu organ. The eight extraordinary vessels run between and across the regular channels. Channel theory underlies acupuncture and also informs herbal medicine through the doctrine of channel tropism — the idea that each herb preferentially "enters" certain channels.