Flush channel / Thoroughfare Vessel
  Flush channel This is one of the standard nomenclatures of the eight extra meridians. It refers to the “sea of blood," which is the place for the 12 normal meridians to converge and where it helps regulate the qi and blood inside them. Sometimes, it also refers to the liver or an acupuncture point. This channel is closely related to the menses.
chong mai 衝脈