The Anatomy & Physiology of TMJ and TMD

The Anatomy & Physiology of TMJ

Primal Pictures

  1. The temporal bone of the skull = Temporo
  2. The lower jaw or mandible = Mandibular.
  3. The structure that holds the two together = Joint.

If you place your fingers on your face directly in front of your ears and open and close your mouth you can feel the Temporomandibular joint in action.

There are a large variety of symptoms (see Signs & Symptoms of TMD) that are associated with temporomandibular disorders. Since it was originally thought that these symptoms had their origin in the Temporomandibular Joint the all-inclusive term “TMJ” was used to describe the condition. Since “TMJ” simply refers to a part of your anatomy, today the term Temporomandibular Disorder (TMD) is the more commonly used term.

The temporomandibular joints are unique set of joints within the human body. They are the only joints able to move in six directions; anterior-posterior (forward and backward), lateral (side-to-side), vertical (up and down), pitch, roll and yaw. One of their main roles is to accommodate or act as a shock absorber when the teeth bite together (Occlusion). When the occlusion is in a state of pathology it affects the central nervous system, C1 and C2, airway, joints and the muscles of mastication (chewing).When both of the joints and muscles have to adjust to a bite that is faulty, it initiates a spastic muscle cycle of fatigue and pain that ultimately affects the rest of the posture of the body as it accommodates to this unnatural position. The end result is a variety of symptoms that are often overlooked or positively correlated to the faulty bite. A traumatic accident, missing teeth, stress, grinding/bruxing, sleep apnea, poor arch development, poor posture with forward head posture or previous dental work can not only affect the bite, muscles, joints and central nervous system, but can dramatically affect the rest of the posture of the whole body.

Showing the relationship of the occlusion( bite ) to C1 and C2. When looking at just the mandible and teeth one can assume that the center of rotation is the Joint since there is a simultaneous rotation and translation upon opening and closing the mouth.More of a class !!! lever system.That is more of a myopic viewpoint. When looking at the whole stomatognathic system it becomes obvious as pointed out by Casey Guzay, that the true center of rotation upon opening and closing is actually C1 and C2. More of a class I lever system. When looking at the whole system rather than just parts of the system allows the neuromuscular dentist to take the complicated and simplify it to make a more holistic diagnosis.

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