According to Five Element Theory there are Twelve Meridians in Pairs:
Element      Yin Organ      Yang Organ
Earth              Spleen                Stomach
Metal              Lungs                 Large Intestines
Water             Kidneys              Urinary Bladder
Wood             Liver                    Gallbladder
Fire                 Heart                  Small Intestines
Fire (Extra)Â Â Â Pericardium*Â Â Â Â Triple Burner*
*The Pericardium is the tissue surrounding the heart, while the Triple Burner is a conceptual organ unique to the Chinese medical system.
Below see images of these acupuncture meridians:
