Woodcut illustration, showing the path of yinwei mai (Yin Tie Vessel), from Jingmai tu kao (Illustrated Study of the Channels), published in 1878 (4th year of the Guangxu period of the Qing dynasty).
Yinwei mai is one of the Eight Extraordinary Channels (qi jing ba mai). It originates at the zhubin (Guest House) point on the foot shaoyin channel, and runs up the inner side of the lower limb. It ascends to the diaphragm and the Adam's Apple, where it comes into confluence with renmai (the Director Vessel, also translated as Conception Vessel), and thence to the lianquan (Edge Spring) point at the root of the tongue, where it terminates. Pathological changes in this channel are thought to provoke pain in the heart and chest (xinxiong tengtong).