New therapy allows predictable resolution of TMJ, Fibromyalgia and other related conditions

Townsend Letter for Doctors and Patients, June, 2005 by Farrand C. Robson

Compensations That Support Oral Functions

Individuals' symptoms primarily result from the physical compensations that are in place in order to maintain oral functions. The throat is a musculoskeletal structure that is maintained largely by ANS mediated muscle contraction. The muscular compensations most frequently seen will be discussed.

Postural Muscle Support of Oral Functions

I. Forward Head Posture

Forward head posture is associated with TMJ problems. (11,12) Forward head posture allows the throat to be more open and is also associated with breathing concerns. This effect has been seen in normal subjects, (13) as well as in those diagnosed with Obstructive Sleep Apnea (OSA). (14) Respiratory dysfunction has been shown to have an influence on TMJ problems along with forward head posture. (15)

II. Jaw Muscle Activity A. Forward Jaw Posturing

When supine, protruding the jaw will open the pharynx by pulling the tongue forward. This occurs either with or without Obstructive Sleep Apnea (OSA) being present. (16) The tongue is a muscle of respiration with reflex response to allow greater airflow. (17-19) Position and boundaries of the tongue are determined largely by the mandible and structure closely associated with the mandible. The vast majority of instances of upper airway problems involve movement of the tongue, when it relaxes back into the pharynx, thereby reducing or stopping the flow of air. Muscular compensations, including postural changes, are needed to allow the throat to be more open.

In an individual with upper airway concerns, the muscles that move the lower jaw forward may have muscle contraction problems. (20) This is then by definition a "TMJ problem." It would, however, be expected that if the pharynx were maintained in a more open state then muscles could relax and muscle contraction and pain would subside. This effect is seen when the mandible is positioned forward with functional orthodontic appliances. We also see a decreased postural EMG activity. (21) Functional demands on muscle may exceed the adaptive capacity of muscle and result in the discomfort seen in TMJ problems.

B. Elevator Muscle Activity

The origin of the TMJ related jaw pain and head pain is made apparent by the Jaw Tongue Reflex (JTR) which often plays a significant role in the maintenance of an open pharynx and supports the ease of swallowing, speaking and breathing.

The JTR is initiated by contraction of the elevator muscles of the mandible, primarily the temporalis and also the masseter muscles. The JTR adds to this by increasing the tone of the genioglossus tongue muscle which then changes the morphology of the tongue and helps open the pharynx. (22,23) The presence of this reflex is not surprising since the pterygoids, masseter and temporal muscles, commonly referred to as the muscles of mastication, are also secondary muscles of respiration.

Initiating elevator muscle activity by clenching when the lower jaw is in a retruded position allows greater ease of breathing in a great majority of patients. This explains the presence of masseter and temporalis muscle pain in patients in whom an impairment of oral functions has been demonstrated. Morning headache and jaw discomfort are commonly seen in these individuals.