TMJ stands for Temporo Mandibular Joint, the joint where your jawbone hinges from your skull just in front of your ears.  The TMJ is a tiny but very complex joint at the center of a great deal of neuromuscular activity.  As a result, injury to a TMJ can cause a surprisingly wide variety of symptoms.

Symptoms – The most common symptoms of TMJ disorders are headaches (including some migraines), facial pain, difficulty chewing, limited mouth opening, “phantom” tooth pain, blocked eustachian tubes (stuffy ears), dizziness, ringing or buzzing sounds in the ears, difficulty hearing, and postural stresses such as chronic neck tension.   All these symptoms rarely occur together in one patient, and most patients suffer from only a few of them.  For example, some only get headaches, some only get facial pain, and some only get ear problems.  A few people also get symptoms like twitching and visual problems that are apparently related to the TMJ condition because they respond quickly to treatment of the TMJ condition, even though we don’t understand the mechanism of their involvement.

Causes - TMJ disorders may be caused by a blow to the head or face, whiplash, postural strains, bite strain, or simply an adult facial growth pattern which causes progressive dysharmony between the jaws and other parts of the face.  A bite that forces the lower jawbone into a strained bracing position every time the jaw is closed may exist without causing symptoms for many years before a failure to adapt to the strain permits tissue damage and clinical symptoms.  Because children have remarkable adaptive capacities, they rarely develop symptoms, no matter how much strain is on their TMJs.  Because stress diminishes adaptive capacity, a period of central nervous system stress can trigger TMJ symptoms in adults simply by diminishing the ability to cope with strain on the TMJs.  That makes stress a contributing factor but not the cause of the condition.

Palliative Treatment - Many doctors treat TMJ disorders by “managing” the symptoms.  Some use  drugs or relaxation, because reducing stress can relieve symptoms just as increasing stress can trigger symptoms. Others use physical therapy, massage, or electrical treatments to restore blood flow in muscles.  Still others tell you to just avoid chewy foods.  These treatments are based on the medical model for acute injury - rest of the affected part.  They often provide short term relief.  However most TMJ disorders are not acute injuries.  They are chronic conditions which require rehabilitation, exercise, and orthopedic support rather than rest and recovery.

Dislocation of the TMJ Disk- The event which initiates the vast majority of TMJ disorders is a dislocation of the disk from one or both of the TMJs.  Joints are designed to hold a cushion (in this case a flexible fibrous disk) between two opposing bones so those bones don’t rub directly together.  Dislocation of the TMJ disk leaves the jawbone rubbing directly against the skull.  The affected joint then functions like a door off its hinges.  The dislocation of the disk often doesn’t cause immediate pain, because the disk is designed to receive compressive forces so it doesn’t have sensory nerves.  However functioning on a TMJ with its disk dislocated can produce a wide variety of symptoms over time.  

Reactive Jaw Muscle Tightness - Jaw muscle tightness then results from the reflex splinting or bracing which occurs automatically in the muscles around any injured joint – much like the automatic leg muscle bracing which would cause limping if you tried to walk on an injured ankle.  Since the jaw muscles are oriented vertically, jaw muscle tightness increases the pressure between the uncushioned bones at the TMJ, thereby increasing tissue damage, causing more jaw muscle tightness, and leading to a vicious cycle which maintains the symptoms.  Subsequently, anything which breaks up the cycle (even an injury) can provide quick temporary relief.  The fact that so many different treatments are able to provide similar short term relief by temporarily interrupting the pain cycle has led to much confusion regarding treatment for TMJ problems.

The Role of Stress - Stress increases the background tonus in all the body’s muscles.  Because of the unique anatomy of the jaw muscles, such an increase in overall tonus can make an existing TMJ disorder problem much worse.  In other parts of the body, the bones are held between equal groups of muscles pulling in opposite directions, so increasing the tonus doesn’t move the bones – it just holds them more tightly.  In the face, the jaw closing muscles are much more powerful than the jaw opening muscles, so a general increase in tonus further increases the vertical jaw closing pressure.  When the joints that must withstand this pressure have lost their cushioning ability, the pressure adds to the same vicious cycle caused by reflex splinting as described above.