This is a series on Jaw pain and TMJ based on the case of Rodney D. Previous posts include muscle information, treatment notes and a Neuromuscular Therapy point of view from my Boston area wellness center.
TMJ Dysfunction results from factors like displacement of the disc in the joint, misalignment of the two sides of the jaw because of a structural asymmetry, an old injury or trauma to the jaw, and overuse of the muscles on one side due to problems with the teeth. Pain can come from inflammation or infection in the teeth or mouth, local pain from tight muscles, and Trigger Points that refer to the TM joint, jaw or ear. Clicking sounds are caused by the disc being pulled out to the front edge of the joint (by the lateral pterygoid which attaches to it) where the bony condyle rubs against it.
With all TMJ and jaw pain complaints, assess the joint first. The patient should be able to relax the jaw with the teeth apart and the tongue behind the upper teeth. For a fully relaxed opening, the tongue drops into the floor of the mouth and the jaw hangs with the lips together. Holding tension makes the joint tight and causes pain. Relaxing the muscles and letting the jaw be slack opens the joint and prevents the nerves from firing due to sustained compression, and prevents the disc from being compressed, damaged and pulled out of place. Ease of movement reduces pain.
For a quick assessment of jaw alignment, have the patient open his/her jaw. Watch to see if it deviates to one side or the other or whether it stays even. Hold your fingers over the joint and feel for disengagement on one side. You’ll feel the condyle pop out. If you have trouble seeing and feeling with the patient in front of you, have him/her lie supine and sit at the head. Seeing the face upside down seems to make these movements clearer and palpation easier.
If there is one-sided disengagement, the patient should be careful to open the jaw like a hinge, keeping the condyle in the joint. When opening wide, they must open both sides evenly. This can be done by placing the fingers on each joint and protruding the lower jaw, then slowly opening, carefully monitoring alignment.
Test the ease of opening by having the patient insert the stacked middle knuckles of the fingers between the teeth. They should easily insert two knuckles. Three knuckles is good range.
The most common Trigger Points referring pain into the temperomandibular joint (TMJ) are the lateral pterygoid, medial pterygoid and masseter muscles.
Pain in or behind the ear is usually Trigger Point pain when it accompanies TMJ pain. Muscles that refer there are the SCM, digastric, longus capitis and deep masseter.
The next post is about stretching the jaw safely.