Integrative Undertanding: Development of the Nervous System

To show a neurological approach to TCM, it is necessary to expand and redefine aspects of the nervous system to include TCM principles. Our nervous system is made up of two components: the central nervous system (the brain and spinal cord), and the peripheral nervous system. The peripheral nervous system (PNS) serves as the connection between the brain and the body and regulates many body processes that are outside of our conscious control and automated. The involuntary, automatic part of the PNS is called the autonomic nervous system (ANS), and it has three components: the sympathetic autonomic nervous system (SANS), parasympathetic autonomic nervous system (PANS), and the enteric nervous system (ENS). For the purposes of traditional Oriental Medicine, the balance of yin and yang in the body is most closely reflected by the balance between the sympathetic and parasympathetic nervous system. (Fang Li, 2015)

The sympathetic (SANS) is the yang part of the nervous system. It is a measure of the effect of sensory stress on the body. It has a positive charge on a voltmeter or galvanometer.
The sympathetic (SANS) is the yang part of the nervous system. It is a measure of the effect of sensory stress on the body. It has a positive charge on a voltmeter or galvanometer.[1] It provides stimulation, the jump start so to speak for movement, and integrates the fight/flight/freeze response. (Alshak & Das., 2023) Upon stimulus, hormones target adrenergic receptors to release neurotransmitters such as epinephrine or norepinephrine to cause contraction, and in states of high arousal, O2-rich blood is shunted to the large motor muscles in the body: contractile strength increases through the heart, respiratory rate increases, medial muscles groups, and digestion are denervated (down regulated or frozen) to allow the body to mobilize resources in preparation for flight.

The yin aspect of the ANS is called the parasympathetic autonomic nervous system (PANS). It has a negative charge on a voltmeter.[2] The PANS serves to calm, inhibiting stress hormones that cause contraction, redirecting resources to digestion, growth, and development. Gastric secretions, smooth muscle interaction, heart rate variability, AV node conduction, and erection in the penis are dictated by the PANS. (Waxenbaum JA, [Updated 2023]) The Vagas nerve (cranial nerve 10) is the largest part of the PANS and vagal tone is a qualitative description of the body’s adaptability to stress, either physical or emotional. It exits from a more primitive region of the cervical spine and intersects with many organs and regions in the body including the limbic system. As such, it is deeply involved in emotional regulation. (McLaughlin KA, 2015) The Vagas nerve (CN X) includes both motor and sensory functions and serves as a counterbalance to the SANS.

Working together, sympathetic and parasympathetic work in harmony to regulate vital processes and coordinate our sense of time and space through the vestibular system. These are mutually antagonistic systems, and except for the heart, stimulating one system diminishes the effect of the other. A biceps muscle held in a strongly flexed position, for example, a (+) sympathetic charge, will show corresponding inhibition of its antagonist muscles in extension, the triceps (a (-) charge). In its role of helping digestion, rest, reproduction, and a state of emotional well-being, the Vagas nerve reflects the patency of yin/Jing in the body.

The largest and most complex part of the ANS is called the Enteric Nervous System (ENS). Having approximately 400 – 600 million neurons, the human ENS is found in two major networks—the myenteric and submucosal plexuses below the diaphragm. ​(Waxenbaum JA, [Updated 2023 Jul 24])​ It is formed in utero, and has its most active developmental state in the peri-natal period through the first several years. Its innervation is both sympathetic and parasympathetic and is the entire pathway for the absorbing the nutrients of food and drink. (referred to in TCM as the production of post-natal qi). It begins with a series of ganglionic plexuses which follow the line of digestion from the trachea to the anus. The ENS is supported through near-constant parasympathetic innervation, with SANS and stress hormones down-regulating its function proportional to the insult. “Rest and digest,” repair, and other parasympathetic functions are inhibited under patterns of fight/flight/freeze.

The ENS is made up of the autonomic nervous system, but it works independently of the central nervous system and can stand alone. For this reason, it is called the gut-brain.
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[1] In his book “Chinese Acupuncture” Goerge Soulis de Morant includes polarity charges when describing the sympathetic and parasympathetic nervous system. 165 acupuncture points were measured with distinct decreases in electrical conductivity on actual sites versus just a few mm away for a point. Additionally, earth scientists have proved that the earth has a mildly negative charge (-), while everything ‘not earth’ has a mildly positive charge.

[2] Multiple clinical trials of the polarity effects of grounding have found that the human body (un-grounded) keeps a mildly positive charge, and when standing on a grounded surface will hold a slightly positive negative charge. Un-grounded, we are slightly yang, and grounded we are more yin.