The Hand-Shaoyin meridian alone lacks the Five Shu points. Why is this? It is said: The Shaoyin meridian is the Heart meridian. The Heart is the great master of the five zang organs and six fu organs, serving as the residence for the spirit of the sovereign. Its organ is solid and firm; pathogenic factors cannot reside within it. If they do reside, the Heart will be injured; if the Heart is injured, the Shen (Spirit) will depart; if the Shen departs, death ensues. Therefore, whenever pathogenic factors are located in the Heart region, they reside in the Pericardium Luo (Pericardium collateral). The Pericardium Luo is the meridian that acts on behalf of the Heart Master. Thus, the Shaoyin meridian has no Five Shu points. Since the Shaoyin meridian has no Five Shu points, does the Heart never become diseased? It is said: Its exterior meridians and fu organs may become diseased, but the zang organ itself does not. Therefore, one exclusively selects the point at the end of the sharp bone behind the palm (Shenmen, HT7).
During the three months of summer, the Heart and Small Intestine are in charge, corresponding to the red blood vessels and KT disease [Note: "KT" appears to be a textual anomaly or specific symbol in the source]. The origin of this condition lies in the conflict and stagnation between the Qi of Shaoyin and Taiyang, leading to the obstruction of Ying (Nutritive) and Wei (Defensive) circulation, resulting in pain and swelling of the skin and flesh. When the movement of the Taiyang meridian triggers pathology in the Shaoyin meridian, excessive pathogenic factors arise, causing the zang and fu organs to be susceptible to summer epidemic diseases at any time. The manifestations of these diseases are similar; if the fu organs are deficient, they are invaded by Yin pathogenic factors...