The master of the heart carries out the functions of the shen; the heart stores the shen. The pericardium, heart-wrapping luo, functions to protect the heart from all types of disturbance. If the heart is injured, the shen will be disturbed and this will result in death or an incurable disease. The master of the heart functions energetically as a communicative pathway for the shen between the heart and the moving qi between the kidneys. In conceptualizing these pathways and functions, it is even possible to see this pathway as the meridian of the "small heart" or ming men: The Su Wen says, "AT the sides of the seventh vertebra on the inside, is the small heart." Mr. Yang, the writer of the Tai Su, says, "There are twenty-one vertebrae in the person. Counting upwards from the lower parts, to the sides of the seventh vertebra, on the left is the kidney, on the right is ming men. Ming men is the small heart." The Nan Jing says, "The source of the heart comes out at PC-7; thus PC-7 belongs to arm jue yin. Wrapping-luo, helping fire, this is the meridian of the small heart." This particular passage from Liu Wan Su gives us a significant description of the pericardium meridian, as it is commonly called, and its various internal trajectories. This significance will become clearer in later chapters. For now, however, we may expand our diagrammatic representation of the internal trajectories to the kidney