ILLUSTRATIONS OF THE VAGAL SYSTEM
As our research on the vagal system proceeded, during the creation of the Official Polyvagal Poster, which went through 19 versions before completion, we began to discover that most anatomical atlases were radically simplifying the depiction of the vagal system, and the drawings of nerves in general. Let's take, as a starting point, the difference between these two drawings of the Trigeminal Nerve (Cranial Nerve V). Here is a fairly standard drawing:
Note how simply drawn it is. Here is a more accurate drawing, showing somewhat more of the ramifying terminations. This is still an over-simplification.
What is invisible, even on the second image, are the finest ramifying terminations of these nerves, which are ultra-fine, the neural equivalent of capillaries. When we apply this awareness more deeply to the vagal system, one of the most startling things we realized, in developing the poster, was that most depictions of the sub-diaphragmatic vagus (the dorsal branches) are almost ridiculously over-simplified. See, for example, these three standard drawings:
None of these drawings give the viewer any sort of accurate sense of the actual density of the dorsal fibers in the enteric system. They make it appear that this system is comprised of several branches nerves, when, in reality, your entire digestive system is more or less cob-webbed full of sub-diaphragmatic vagal neurology. We began to uncover this, interestingly, with encounters through practitioners working in non-allopathic approaches to healing, including osteopathy, energy medicine, and acupuncture. When we then began combing anatomical atlases, we came across this drawing, in the Atlas of Human Anatomy and Surgery, J.M. Bourgery and N.H. Jacob, published by Taschen:
In this drawing, the heart is cut away, so you can't see any of the neurocardiology of the vagal system, but note first the number of fibers passing through the respiratory diaphragm, and second the number of nerve plexi behind the cut-away of the stomach. That is closer to what your actual enteric nervous system looks like. Again, even on this diagram, the finest terminations and ramifications are omitted. This is clinically of great significance because it helps you understand right away, that the vagal neurology of the Autonomic Nervous System is massive, extensive, and pervades the interior space of the body. As our neuroception changes, the physiological parameters of the body, via these vagal conduits, are almost instantaneously shifted. As you begin to grasp the penetration and extent of these systems you realize how profoundly they shape our moment-to-moment visceral and felt experience of everything.