If we equate the skin perforating branches with “Sun Luo (孙络)”, it will lead the subsequent research on skin perforating branches into a wrong path.The blood vessels supplying the skin are called skin perforating branches. Everyone understands the blood vessels supplying the skin; anyone who has studied middle school biology knows this. However, the concept of skin perforating branches is not well understood. This is because, from the perspective of microsurgery, blood vessels have been further classified and various concepts have been refined, making it very specialized. Therefore, practitioners of Traditional Chinese Medicine (TCM) who are not exposed to modern medical advancements may think that since they are all skin blood vessels, Sun Luo and Luo Mai (络脉) are similar. This is indeed a significant misunderstanding.Moreover, it is crucial to note that TCM literature has not meticulously examined the relevant content of Sun Luo.
We must clarify this.
There are two ways to dispel this misunderstanding. One is to participate in my anatomical exploration research to personally observe the morphology of the human body while referring to the relevant descriptions in the Huangdi Neijing (黄帝内经). You can join the WeChat group. After using the calf last time, this time I plan to use the forearm to observe the morphology of the skin perforating branches.
The second method is to examine how the term “Sun” is used in the Huangdi Neijing; what the chapter concerning Sun Luo entails. A substantial semantic comparison with Western medical content is necessary. We cannot merely focus on the wording, especially the phrase “branches and horizontally form Luo, the distinction of Luo is Sun” does not represent much. Of course, I generally use a more comprehensive version of the Huangdi Neijing – Xuan Yin Yi Mi (玄隐遗密).
1. The Original Meaning of Sun
To its offspring, it must act..
When the upper and lower are harmonious and kind, virtue flows down, and the offspring are without worry, passed on to future generations, without end, can it be heard? Gui Yu Qu says: The mechanism of numbers is subtle and minute,
In the Xuan Yin Yi Mi, the term “offspring” is used, indicating that Sun refers to the next generation of Zi (子). This is consistent with today’s usage. If corresponding to blood vessels, it refers to the branches of branches.
Skin perforating branches are mostly primary branches of the main artery, sometimes secondary branches. After entering the skin, they will further branch three times. If we categorize the capillaries from the main artery to the skin into three levels, the skin perforating branches are certainly at the sub-level, while Sun Luo is inevitably at the grandchild level, which corresponds to the capillaries and the blood vessels before and after the capillaries.
2. “Summer takes Sun Luo” and similar content
“Thus, decoctions, sweet drinks, and medicinal stones each have their own pathways. Acupuncture has its distinct methods, and Qi points are fixed. If obtained, it should be stopped; if lost, it should be retained. In spring, take the meridians, dividing between the flesh. Therefore, it is very deep, and the intervals are shallow. In summer, take its fullness, the great meridian Sun Luo, taking intervals, and cutting off the skin. In autumn, take the meridian; the evil flows into the organs. In winter, take the well and the ying, retaining it deeply.”
This passage represents that summer taking Sun Luo does not fundamentally discuss the category of the “Five Shu Points”. There is a preceding modifier for Sun Luo called “great meridian”. The subsequent text also has similar content, giving the impression that summer taking Sun Luo is very similar to bloodletting, rather than the function of “regulating Qi and blood” commonly associated with acupuncture points.
The classics say: In spring, the weather begins to open, the earth’s Qi begins to leak, the frost thaws, and the water flows through the meridians, hence it is said: Human (Qi fire) is in the pulse; in summer, the meridians are full, (Qi fire) overflows, Sun Luo receives blood, and the skin pores are filled; in the long summer, the meridians are all flourishing, overflowing into the muscles; in autumn, the sky (Qi fire) begins to collect, the pores are blocked, and the skin is tense; in winter, the earth’s Qi gathers and hides, blood (Qi fire) is within, and enters the bone marrow, connecting to the five organs. Therefore, the evil ones
This passage indicates that the concept of Sun Luo further extends to those less commonly used capillary pathways within the capillary network. Only a portion of the human capillaries are open, and Sun Luo receiving blood may refer to a broadly developed state.
This further illustrates that skin perforating branches are not Sun Luo.
3. Sun Mai (孙脉) and Sun Luo are two concepts
Thus, the harm from wind and rain first affects the skin and hair, then transmits to Sun Mai. When Sun Mai is full, it enters the guest in the Luo Mai. When Luo Mai is full, it enters the guest in the Jing Mai.
In this passage, Sun Mai can be understood as the arterial part of the branches of skin perforating branches, where the superficial sympathetic nerve components are relatively sensitive, affected by cold, leading to vascular spasms, resulting in insufficient blood supply to the capillaries, causing local microcirculation disorders. With the fluctuations in microcirculation disorders, the return veins of the capillary network also encounter issues. This arterial and venous relationship is interdependent and mutually influential. The blood vessels one level above the capillary network are the branches of skin perforating branches, and the connection of branches is the meridians; from the perspective of branches, calling it Sun Mai is also appropriate. This passage distinguishes between Sun Luo and Sun Mai.
When the form is where the evil resides, it first leaves the skin and hair, remaining and not leaving. Then it enters the residence of Sun Luo, remaining and not leaving. Then it enters the residence of Luo Mai, remaining and not leaving. Then it enters the residence of Jing Mai, remaining and not leaving.
This passage reveals the hierarchy of Sun Luo, Luo Mai, and Jing Mai. In my view, when using Sun Mai, it emphasizes arterial function, while using Luo Mai emphasizes venous function. Sun Mai and Luo Mai cannot be interchanged; it depends on the context.
When the disease is in a person, it cannot be singular. It can be in Sun Mai, in micro Mai, in Hui Gu, in Liu Xi, in Da Luo, in Jing Mai. It may be in Shu Mai, or in the Fu Chong Mai, or in the Guan Chong Mai. It may be in the eight extraordinary meridians, or in the part of the muscles, or in the stomach and intestines, or in the six Xu, connecting to the brain.The evil Qi is excessive, and cannot be fully expressed.
When it is in micro Mai, the skin is dirty and the skin is stained. When it is in Hui Gu, the joints ache. When it is placed and accumulates, it causes pain when moving. When it is in Liu Xi, it is a disease of cold and heat imbalance. When it is in Da Luo, the Yin Mai is muddy and the pulse is floating and knotting. When it is in Jing Mai, dampness is obstructive, and pain arises. When it is in Shu Mai, there is a tax (meaning from two piles of water) that is not balanced. When it is in Fu Chong, the gallbladder Qi does not reach, the fluids are not transformed, and there is severe pain at times. When it is in Guan Chong, the tendons are tight, stiff, and not beneficial, and the soreness persists. When the eight meridians retain evil, the organ Qi is unbalanced, excessive and not noted, cold and heat are different. The bowel movement is poor, the collection is rejected, the six Xu are unbalanced, and the regulations are chaotic.
When it is in Sun Luo and forms accumulation, its upper and lower interactions are in the arms and hands of Sun Luo, floating and slow, unable to accumulate and stop. Therefore, it easily travels between the intestines and stomach, the water flows and seeps, washing and making sounds, when cold it causes anger (from moon and truth) and fullness, hence the pain at times. When it is in the Yangming meridian, it resides at the navel, when full it increases, when hungry it decreases. When it is in the slow tendons, it is like Yangming, when full it causes pain, when hungry it is peaceful.
This part of the text discusses diseases in the pulses and various symptoms in different pulses. However, there is no mention of Sun Mai.
The third paragraph discusses the accumulation formed by Sun Luo. Vascular spasms or insufficient vascular pulsation can be adjusted by Qi and blood to recover in a short time. However, the persistent dysfunction of the capillary network’s microcirculation can easily accumulate over time; once it becomes a chronic disease, it is termed “accumulation”, leading to various issues with the internal organs, which TCM may refer to as “dampness”. In the subsequent text, the diseases caused by accumulation present various internal organ manifestations.
My understanding of these three paragraphs is that when it is Sun Mai, the pathological changes are not obvious. When it progresses to the next level, which is micro Mai, the skin shows dirtiness, so if you see uneven skin color on the body, it indicates a problem with micro Mai. This content does not conflict with the previous text.
Further up, larger structural issues in the body indicate that the range of pathological changes is expanding.
4. Bloodletting generally refers to letting blood from Sun Luo.
The meridian is the pathway that determines life and death. Regulating all diseases, transforming the virtual and real from the outside, one must secure its openings and adjust its pathways. Therefore, the sage uses acupuncture and stone therapy, dispersing and warming the pathways, promoting the stagnation of the meridians to treat the suffering, thus following the natural laws and applying them. Therefore, when the spirit is abundant, it smiles; when insufficient, it worries; when essence is abundant, it is vigorous; when insufficient, it is fatigued; (Qi fire) when abundant, it moves; when insufficient, it is sad; when blood (Qi fire) is clear and upright, the five organs are stable, the evil resides in the form, and the Qi rises in the hair, hence it does not enter the meridian but first the Luo, called the subtle disease of the spirit. When the spirit is abundant, let the blood of the small Luo flow; the small Luo is Sun Luo, do not let it be too deep, do not drain it too much, to open the meridian, the spirit (Qi fire) is thus balanced. When the spirit is insufficient, observe its virtual Luo, and treat it, needling to benefit it, without letting its blood out, do not leak its Qi, to open its meridian, the spirit (Qi fire) is thus balanced.
This passage clearly states that the disease begins from the hair, meaning that external evils first harm Sun Luo or Sun Mai. At this time, it is called harming the spirit. If the person’s emotions are normal, then one can let blood from the small Luo, which are the fine, thread-like blood vessels commonly seen on the skin; and do not pierce too deeply, nor let out too much blood. If the emotions are not normal and are low, then stimulate the tissues adjacent to the large Luo. Because the large veins often have accompanying nerves and small arteries, stimulating these through acupuncture can accelerate the blood flow of the large veins.
This acupuncture method may scare readers, as using needles to pierce the skin and let blood can be intimidating. According to the principles of this TCM saying, theoretically, there is another part that can achieve a similar effect. Using a home blood pressure cuff, wrapping it around the upper arm, inflating it beyond the systolic pressure, without releasing, but continuing to apply pressure to the upper limb while repeatedly clenching the fist, this applies a certain pressure to the superficial Luo. Afterward, release the tourniquet. Of course, one can also use the rubber tube used during blood draws as a tourniquet.
5. The relationship between Luo and Sun Luo
How to understand this term? It can only be found in the original text.The following passage is very long, and one must read the entire text to understand “the relationship between Luo and Sun Luo”.
The classics say: If the kidney Qi is deficient, it will cause counterflow and upward rush. If it is full, it will cause distension and movement between the bones and tendons. To treat fullness, one should drain and let blood; if insufficient, one should supplement and retain. If the disease has not manifested, take Yongquan, Dantian, and Mingmen as references, and the evil will depart when the right is established.
The classics say: The patient has evil entering from the outside, riding on the Qi and blood. This causes the Yin and Yang to thin, Qi to be chaotic in the Wei, and blood to reverse in the Jing, blood and Qi (Qi fire) separate. One is full and one is empty, blood is combined with Yin, Qi is combined with Yang, hence it causes fright and madness. Blood is combined with Yang, Qi is combined with Yin, hence it causes heat. Blood is combined above, Qi is combined below, causing irritability and anger. Blood is combined below, Qi is combined above, causing chaos and forgetfulness.
The classics say: Qi and blood prefer warmth and dislike cold; when cold, it weeps and does not flow, hence it should be warmed to dissipate. Therefore, where Qi is combined, it is blood deficiency; where blood is combined, it is Qi deficiency. Therefore, when blood is mentioned, it exists as real; when not, it is virtual.
When Qi is combined, there is less blood; when blood is combined, there is less Qi. When blood and Qi (Qi fire) are lost, it is thus deficient. The relationship between Luo and Sun Luo, both flow into the Jing, blood and Qi combined are thus real. Blood in Qi, and both flow upwards, it is great counterflow, and counterflow leads to sudden death. If Qi returns, there is life; if it does not return, there is death.
6. The separate meridian of Sun Luo
The classics say: The separate meridian of Sun Luo, its blood and Qi (Qi fire) are abundant and should be drained, also three hundred sixty-five meridians, all reside in the Luo, transmitting to the twelve meridian pulses, not only the sixteen Luo pulses, but also ten pulses that drain internally.
This passage, from the perspective of Western medicine’s skin blood mechanism, is very clear. Skin perforating branches are accompanied by arteries and veins, but many skin perforating branches’ arteries and veins are not of equal caliber. This means that much of the blood from the skin perforating branches cannot return through the corresponding accompanying veins. The most typical example is the Jing points, where the arterial blood from the Jing points becomes venous blood, all returning from the subcutaneous veins to the large veins.
7. Luo Mai – the meridian with Luo function
The master says: Not knowing is not enough to speak of meridians; not knowing the reasons, how can one know the reasons? The Yu points are where the meridians pass, the Luo is where the diversion flows, and the Xi Gu is the supply of nutrition to the skin and flesh.
The meridian is the great way, and the Luo Mai is the transporter. The Xi Gu is the nourishment provided to the muscles and joints, pushing and renewing.
The injection of Sun Luo is continuous, describing the inflow and outflow of blood in the capillary network without ceasing.
In summary, Sun Luo cannot be regarded as skin perforating branches. The concept of skin perforating branches cannot be substituted into so many contents related to “Sun”. To consider skin perforating branches as Sun Luo, on one hand, shows a lack of understanding of the concept of skin perforating branches. On the other hand, it misinterprets the content of Sun Luo and Sun Mai in the Huangdi Neijing.
If you want to understand the concept of skin perforating branches in detail, you are welcome to join my anatomical exploration work.