The autonomic nervous system innervates – or supplies with nerves – almost every tissue and organ in our bodies. It innervates our heart, arteries, lungs, lymphatic system, our gut, and much more.
The autonomic nervous system shifts between two states: the “rest and digest” state (parasympathetic) and the “fight or flight” state (sympathetic). We can envision this as two different circuits. When the switch is on parasympathetic mode, the whole body synchronizes as one to function in a restorative mode. Your heart rate slows down, your blood pressure drops, and blood is diverted to flow to the gut in order to restore digestion and absorption of nutrients after you eat.
Conversely, when the switch is on sympathetic mode, the body synchronizes to function in a state of alert, commonly known as “fight or flight.” Your heart rate increases, blood pressure increases, pupils dilate, the bronchioles of the lungs open to receive more oxygen during inhalation, and blood is diverted away from the gut to the large muscles of the body.
These two circuits of the autonomic nervous system can shift from one state to another throughout our day. In the mornings, the sympathetic nervous system activates to wake the body, and in the evening, the parasympathetic nervous system helps the body restore and sleep.
With an understanding of the function by which these circuits govern physiology, we can begin to discuss the landscape through which the autonomic nervous system resides in our anatomy.
Sympathetic Nervous System Landscape
The landscape of the sympathetic nervous system is extensive and connects the whole body. The sympathetic nerve fibers arise from the spinal cord at the level of our upper and lower back (thoracic and lumbar spine). As the nerves exit the spinal cord, they enter a relay station (ganglia) by which they interact and then continue to their destinations – heart, lungs, muscles, etc. These relay stations can be found along the spine, from the neck to the tail bone, as well as in the viscera of the abdominal cavity.
Parasympathetic Nervous System Landscape
The parasympathetic nerve fibers extend from cranial nerves in the skull and from the sacrum (tail bone). The parasympathetic nerves – which bring restorative function to our physiology – exit through the top and bottom of our spine.
Osteopathic Manipulation for the Autonomic Nervous System
In the mindfulness world, we have learned different ways to influence our autonomic nervous system – e.g., guided meditations and breath work. We can also influence the function of our nervous system through hands-on osteopathic manipulation of the anatomy.
In Osteopathy, we assess the tissue texture, asymmetry, and motion of the cranial bones, brain, spine, connective tissue, muscles, bones, and fascia to assess the ease by which these nerves communicate.
If you are tense in your shoulders and upper back, the functioning of the nerves is impacted. The neck and upper back are anatomically connected with our sympathetic nerves. As such, if an individual rotated a vertebra in the upper back and had hypertonic (tense or contracted) neck muscles, by association, the nerves passing through are affected. If the nerves are compressed or stretched, they may become overactivated or underactivated.
Dysfunction in Our Landscape
I often diagnose anatomical dysfunction in the relationship of the head on the neck. The occiput – the cranial bone in the back of the head – has a hole through which cranial nerve 10, the vagus nerve, flows. The vagus nerve is a large nerve responsible for parasympathetic activity. If the head is restricted in a side-bent position, the passage through which the vagus nerve passes is affected.
The vagus nerve plays a critical role in our digestive system. If the vagus nerve is not firing appropriately, it affects the stomach and our capacity to digest food and absorb nutrients. Optimizing our dietary nutrition is not enough if the gut is not receiving appropriate vagal stimulation to digest and absorb the food. This dysfunction is easy to diagnose, just by observing the way someone carries their head – is the person’s head slightly tilted? Or rotated to one side?
Why Do We Get Dysfunctions?
The head and spine often compensate for prior injuries, stress, surgeries, poor posture, or trauma such as car accidents or concussions. The compensation is often expressed by rotation and bending of different parts of the spine in order to optimize the body’s overall functioning. However, these compensatory patterns, if unresolved, can lead to chronic injury or illness if untreated.
Integrity of the Landscape
The synchrony and fluctuation of the autonomic nervous system are vital in optimizing the body’s capacity to grow, absorb nutrients, fight infection, heal, and sleep. Our lifestyle frequently entails prolonged periods of sitting, inactivity, and minimal exposure to the natural world – all of which contribute to dysfunction. This dysfunction inhibits the body’s capacity to express health and balance within our own natural physiology.
Osteopathy improves structural integrity to optimize the functioning of the body.
Osteopathic manipulation addresses the autonomic nervous system, embedded along the spine from our head to our tailbone. It restores proper tension and motion, to promote healthy expression of the nerve signals.