My first post is more pertinent to the practice of acupuncture than to herbalism, but I consider it relevant to the theme of this blog, since one of the primary goals of this blog is to develop a medical understanding and theory which integrates Biomedical, Chinese, and Anthroposophical findings. The present essay is an effort at developing an integrative anatomy.
I. Arm
Nerves of the Arm
The median nerve corresponds well to the the PC channel in the fore arm and upper arm. The palmar branch of this nerve splits off at PC6, or maybe PC5.
The ulnar nerve corresponds strongly to the HT channel (and somewhat to the SI channel) in both fore and upper arm. The dorsal branch splits above HT4.
The Musculo-Cutaneous Nerve is distributed on the LU channel (and somewhat on the LI channel) in the fore-arm. Its distribution on the upper arm is somewhat unclear to me. It is rather deep in the upper arm, so this may be irrelevant.
The Radial Nerve does not follow a clear single channel path - it winds and branches - but it emphasizes the TB channel, especially in the forearm. It is present under LI11 (the LI and TB channels are running very close to each other here). In the upper arm it may be accessible at TB13, which is the meeting of the TB channel and Yang Wei Mai. The superficial branch of the radial nerve emerges as LI6 and then spreads over the area around Hegu. The cutaneous distribution of this nerve is strictly TB region in the forearm.
Arteries of the Arm
The Brachial Artery follows the HT/PC channel in the upper arm, It is present under PC3. In the forearm it splits into the radial & ulnar arteries, following the the LU & HT channels, respectively. The radial artery begins branching into the hand at LI5 (the anatomical snuffbox). The corresponding point in the foot is ST42 where the Dorsalis Pedis branches into the foot.
Veins of the Arm
Veins are interesting. I will be arguing later that veins are (roughly) the TCM luo-connecting channels. There are two main veins in the arm: the Cephalic and the Basilic. These veins start on the yang aspect of the distal forearm and swing around to the yin aspect at or around the level of LI-6 (the luo point of the LI channel). From this point the Basilic vein follows the HT channel and the Cephalic follows the LU channel up to LU 1, where there is a lymph node (the deltopectoral node). There is no vein which runs the course of the PC channel, but the Median Cubital Vein runs between the two main veins, across the PC zone of the proximal forearm, in an area where there are no TCM points, but where I often like to needle the PC channel when I am following my palpation.
Thus:
LU - Musculo-cutaneous nerve; Radial Artery; Cephalic Vein
LI - nothing notable except a bit of the cephalic vein
HT - Ulnar Nerve; Ulnar Artery; Basilic Vein
SI - nothing notable except some of the Basilic Vein
PC - Median Nerve; no artery; (median cubital vein)
TB - Radial Nerve
Cutaneous Innervation
Of interest perhaps to those practicing Meridian Style needling. A clear chart can be found on Netter p. 481, so I'm not going to summarize all this info in writing. I will simply note that from a cutaneous point of view, the PC channel does not exist on the arm (cutaneously, the median nerve innervates only the palm of the hand) while the LI channel shares innervation with the LU channel and likewise the HT & SI channels have the same innervation. The Median Nerve and the Ulnar nerve, which run in the PC and HT channels, are the two nerves which innervate the palm of the hand. This strongly emphasizes the Shen / consciousness function of these channels, since the palm is the most sensitive part of the most "head-pole" aspect of the upper limb. The TB zone of the forearm is innervated by the Radial Nerve, but in the hand this nerve goes into LI territory. On this evidence, we might consider amending the location of TB2 and 3, placing them between the index and middle fingers (ie TB3 would take the place of extra point luo zhen). For those hesitant to question the ancient sages on a scant hint from western anatomy, consider that this location would continue the symmetry between the TB and PC channels onto the hand, since TB3 would be located opposite PC8 instead of opposite HT8. (It would however destroy the consistency of locating the shaoyang channels on the fourth digit). From a pragmatic/clinical perspective, consider that in Dr. Tan style these two locations (ie between index and middle fingers and between ring and little finger) are usually used together.
II. Legs
Things are less clear-cut in the legs. Although I have managed to make a somewhat clear summary below (I hope), it took me much longer to trace and figure out the anatomical features of the leg.
Nerves of the Leg
The Saphenous Nerve (the longest branch of the femoral nerve) follows the LV and SP channels. Emerging through the groin, it is distinctly in the LV channel by mid-thigh. In the lower leg it is unclear whether it is in the LV or SP channel, but its innervation clearly extends to both, and it follows the SP channel along the inside of the foot. The obdurator Nerve also plays some role in innervating the SP & LV channel in the thigh, but it does not extend into the lower leg.
The Sciatic Nerve generally follows the BL channel. This nerve branches above the popliteal fossa, so that the Common Fibular Nerve is present under BL39, while the Tibial Nerve is under BL40. At BL40 the Tibial branches again, with the Sural nerve running more superficially, following the BL channel the length of the leg, and onto the foot. The rest of the Tibial Nerve goes deep, largely following the BL channel, but as it nears the foot it swings toward the medial malleolus and then onto the plantar surface of the foot, suggesting a KD channel affinity.
The Deep Fibular Nerve follows the ST channel
Superficial Fibular Nerve follows the GB channel
Arteries of the Leg
The Femoral Artery follows the LV channel in the thigh. Above the knee, it swings toward the knee, to be present under SP10. It then crosses through the knee to the Yang side of the leg, where it branches into the Anterior Tibial, Fibular, and Posterior Tibial Arteries. Around or perhaps below ST36, the Posterior Tibial Artery branches and returns to the LV/SP channel.
In the lower leg, the Anterior Tibial Artery follows the ST channel. This artery splits into the foot at or around ST-42 (Yuan Source Pt of the ST channel; the deep fibular nerve also splits here.)
More deeply, the Fibular Artery also follows the ST channel.
The Posterior Tibial Artery runs under the tibia, so you could say it is on the LV channel, and it does emerge into LV4/SP5.
The Popliteal Artery follows the BL channel, of course.
Veins of the Leg
The two main veins of the Leg are the Great Saphenous Vein and the Small Saphenous Vein. The Great Saphenous Vein generally follows SP/LV channel in the lower leg. At the knee it swings back to be present at KD10, and then swings forward again to the LV channel of the thigh. The small saphenous veins basically follows the BL channel to the popliteal fossa where it goes deep and becomes the popliteal vein.
The Veins of the leg do not have the clear channel affinities or the yang to yin swing as they have on the arm. However, there are some signs that they still have a luo-connecting quality. Veins running from the toes of the ST channel join veins from the SP channel at or around SP4 (the luo point). Even more notably, a vein originating from the GB region of the foot joins the Great Saphenous around LV5 (luo pt). Again, there is a vein from KD4 (luo pt) to the BL channel. It is true that veins interconnect a lot more than arteries, so some of these junctions at luo-connecting points might just be coincidence, but I would argue that the much-connecting nature of the veins is part of what makes them akin the luo-connectors.
Thus:
ST - Deep Fibular Nerve; Anterior Tibial Artery, Fibular Artery
GB - Superficial Fibular Nerve,
BL - Sciatic/Sural/Tibial Nerve; Popliteal artery; Small Saphenous/Popliteal Vein
LV / SP- Saphenous Nerve; Posterior Tibial Artery; Great Saphenous Vein
KD - a hint of the Tibial Nerve; a touch of the great saphenous vein
Cutaneous Innervation of the Leg
Netter contains no single chart for cutaneous innervation of the leg, so I will summarize here. In the upper leg all cutaneous innervation is derived from the Femoral nerve, which branches around LV10 or 11 into Lateral (ST & GB), Anterior (3 Yin), & Posterior (BL) Cutaneous branches. In the lower leg, the three Yin channels are also innervated by the Saphenous branch of the Femoral Nerve. The BL channel is innervated from the sciatic (sural) nerve. The GB and ST are innervated by two different branches of the sciatic: the common fibular nerve for the proximal part and the superficial fibular for the distal portion, running down onto the foot and covering most of the dorsal surface of the foot. There is a very curious patch on the foot right at LV3 which is innervated by the deep fibular nerve. Cutaneously this nerve innervates only LV3, but it runs in the ST channel, hinting at a yangming association that is especially intriguing in light of the use of this point in the four gates.
III. Observations & Conclusions
Some of the specific correlations I found are intriguing and tantalizing but since I have basically no idea how acupuncture works, it is hard to do much with them. However, comparisons between the arm and the leg do yield some general tendencies which may help with our thinking about the use of channels and points.
First, the more orderly flow of nerves and blood in the arm compared with the confusing distribution in the leg is suggests, from an Anthroposoical perspective, that the arm has a nerve-pole affinity while the leg has a stronger metabolic-pole affinity (orderliness=form pole, asymmetry and chaos = metabolism). This is of course well in keeping with their upper and lower location on the body. I can see this directly influencing how I choose my points.
Second, nerves, arteries, and veins in the arm tend to be shared between between yin-yang / interior-exterior pairs. In the legs, nerves, arteries, and veins tend to be shared between neighbors of similar polarity. Thus LV, SP, and to some extent KD share, while ST and GB share. There is probably some deeper meaning to this, but I cannot yet discern it. At this point I can only say that if I want to focus on strengthening the interactions between yin and yang, I will try to emphasize the arm, while if I want to focus on one of the poles I will emphasize the leg.
