Bodywork Therapies – Brain and Nervous System
The brain receives a constant stream of reports (tens of thousands of messages per second) from nerve structures in the limbs, such as Ruffini nerve endings and Pacinian corpuscles, that register motion, temperature, pressure or pain. This information relates to what is happening in the different parts of the body and answers a multitude of questions that the brain asks, such as: Is the left arm moving? If so, how fast and in what direction? What is its temperature? Is anything pressing on it? Is there any pain? In this way, the brain learns what is happening to every bone, muscle, joint, tendon and ligament – even in the furthest reaches of the fascial web.
After interpreting the received information, the brain sends instructions, via the nervous system, that enable us to walk, talk, maintain balance, move, function and live our lives. Some bodily functions, such as digestion, the rhythmic contraction of the heart and breathing, are on “automatic pilot”, outside of our conscious control. Other functions, such as walking and talking, are directly influenced by conscious decisions.
Problems may arise as a result of various sources. For example, when the brain either receives inaccurate information from faulty nerves or else misinterprets correct information; when the brain sends inappropriate instructions to the tissues and organs; and when reflex activities are either excessive or diminished.
Many nerve functions are reflexive in nature, which means that responses do not have to be ordered by the brain, but can take place via “short-circuit” pathways in the spine. Perhaps the most familiar example of this is the “knee- jerk” reflex reaction.
When spinal structures are injured or stressed, the normal behaviour of vertebral joints may change. This may irritate or compress the nerves that emerge from it, with the potential to influence the organs and other tissues that they serve. This is known as a somatico-visceral reflex.
Similarly but in reverse, when an organ or tissue is unwell the spinal regions associated with it can become distressed, tense and painful. This is known as a viscero¬somatic reflex. A common example is the tense, sensitive region of the upper back (2nd, 3rd and 4th thoracic vertebral areas) frequently noted in people who have heart problems. Some osteopathic and chiropractic practitioners use this knowledge in their work to attempt to modify the negative feedback pathways to the organs.
Although treatment of such spinal areas cannot “cure” organ disease, there is evidence that it brings some benefit. Awareness of these reflex pathways can also help to explain the appearance of many spinal problems that do not have an obvious mechanical cause.
Nerves conduct electrical messages and carry “trophic substances”, such as proteins, essential fatty acids and neurotransmitters, to and from the target tissues and organs they serve. This movement of substances along nerve pathways is known as axonal transportation.
According to osteopathic research, any interference with nerve function, message conduction or axonal transport, in either direction, can cause a wide range of symptoms. Mechanical deformities, such as compression and stretching, and sustained hyperactivity of nerve cells in sensitised spinal segments can slow down axonal transport. Appropriate mobilisation and manipulation of soft tissues and joints may be able to improve these functions.
Sympathetic and parasympathetic actions
The nervous system can be broadly divided into two parts. The role of the sympathetic nervous system is to mainly stimulate tissues and organs, whereas the parasympathetic nervous system has the opposite effect. It mainly calms, inhibits or damps down the activities of the tissues and organs. These stimulating and calming effects of the nervous system can be hugely affected by both emotions and biochemical factors, such as hormonal balance, diet, drugs and allergies. The nerves of the body are therefore capable of becoming sensitised (hyper-irritable), as well as being potentially inhibited, by biomechanical, psychological and/or biochemical influences.
Ultimately, nerves feed into the central nervous system and the brain. At times, this central control mechanism may be responsible for excessive or diminished nerve activity. Just as a local muscle area may become hyper-irritable if repetitively stressed – forming a trigger point, for example – so the central nervous system, or parts of it, including parts of the brain, can become sensitised when bombarded with pain and distress messages, or when biochemically disturbed. This central sensitisation can make the nerve and brain structures far more easily irritated, interfering with accurate interpretation of the messages received from the body and sending inappropriate instructions in response. Central sensitisation is thought to be a major part of what happens in many chronic pain conditions.
Entrapment and compression
Many nerves are vulnerable to mechanical interference because they pass through or around structures, such as muscles and bones, that can trap and/or compress them. Many symptoms result from such situations. Entrapment is usually the excessive pressure that soft tissues place upon a nerve. For example, when the scalene muscles in the neck or the pectoral muscles in the upper chest impinge on and
crowd the nerves running towards an arm, a variety of pain and numbness symptoms can be felt in the arm. This is a condition known as thoracic outlet syndrome, or TOS.
An example of compression is when the arch of bones and fascia in the wrist press on the median nerve. This is known as carpal tunnel syndrome, which is commonly caused and always aggravated by overuse. It may also be partially caused by fluid retention involving swelling of the lower arm or hand.