Neuromuscular Dentistry Science – Proprioceptive Avoidance Conditioning and the Reticular Activating System: What Makes It Work – Part 2
by Clayton A. Chan, DDS, MICCMO
The mandible will always strive to position itself for maximum stability. Factors causing instability, such as occlusal insufficiency, will set up a proprioceptive avoidance conditioning response causing the neuromuscular postural system to adjust its movements and avoid negative stimulation. These adjustments are controlled by the central nervous system (CNS).
The chain of motor movement events initiates an avoidance pattern of responses controlled by the CNS known as sensory engrams. Motor movement patterns are established in the cortex of the brain which are memorized. Once the sensory cortex memorizes the learned engrammed motor movement patterns the memory begins to respond and perform in the same sequential accommodative manner to which the teeth, muscles, jaw joints, head and neck are accustom to performing.
The teeth are the most static or least to accommodate compared to the surrounding musculature and jaw joints. The need to continually accommodate to the static occlusal habitual (often over closed bite) strains the accommodative system of the postural muscles of the face, head and neck culminating in an avoidance conditioning – chronic muscle hyperactivity.
Chronic hyperactivation of the muscles initiates excitation to the reticular activating system (RAS) which is a network of nerves in the central part of the brain stem. It is within this brainstem that our awareness of the world and our abilities to think, feel, love, act and respond are stimulated as the “waking center” of thought to occur. The reticular formation has a direct control on muscle reflexes and muscle tonicity. Signals are sent to this center which awakens the cortex and interprets the sensory and motor signals from the various parts of the human body to the brain (reticular formation). Under normal conditions the reticular formation helps to regulate or depress the amount of cortical activity. When normalized or tonic reticular formation activity is disturbed (eg. chronic muscle hyperactivity conditions) the inhibiting process is diminshed and an overall arousal state increases. Muscle tonicity is a state of partial contraction of the muscle spindles which help to regulate resting tension of muscles. With neural feedback via the reticular activating system, any hypertonicity of the musculature will cause a disturbance of the reticular formation escalating a feedback loop of increased muscle tension.
A persons heightened emotional state will also effect or aggrevate muscle tension and influence the reticular activating system feedback loop resulting in states of anxiety, fear, sleep disturbance and a feeling of uncertainty. These are conditions common with those individuals experiencing TMJ/TMD further compounding the problem and perpetuating the hyperactive muscle pain cycle. The same principles of physiology hold true for all individuals involved in athletic sport activities.
More information: The K7 Chan Optimized Bite Science and How It Works – Part 1
