What is TMJ/TMD?

The Temporomandibular joint (TMJ or TM joint) is the most unique joint in the whole body as it is two jaw joints in one. The two joints located one on each side of the head, are connected by the lower jaw bone. One TM joint may influence the position of the other TM joint. Because they are fused in the midline, this means that you cannot move one TM joint without moving the other. The two TM joints may differ in size, shape and even function. It is possible to have a problem in one TM joint but have no symptoms expressed in the other TM joint. You could also have a pain that starts on one side of the head and migrates to the other side simply because of the relationship of these two TM joints to each other.

The second factor making the TM joints unique is that another structure dictates their function. This other structure is the teeth. The teeth are passive members of the upper and lower jaws, but they have a specific way that they must fit together and interrelate. As far as the brain is concerned, tooth position has priority over joint position. This means that the TM joint is forced by muscle to move so that the teeth will fit together properly. This can potentially cause a mal-alignment within the TM joint capsules. If this happens, the surrounding muscles are put in a compromising situation causing them to spasm, and the result is pain and restricted or uncomfortable movements of the lower jaw. Many of the problems you may be experiencing are a result of muscle spasm, but the cause is not the muscles. The muscles are simply caught between two positions: the tooth position and the jaw position.

The third factor making the TM joints unique is that they have an articular disc located between the ball (condyle) and the socket (glenoid fossa). Each disc within a TM joint has a muscle attached to the front of it that pulls the disc forward as the condyle moves forward in the glenoid fossa (when you open your mouth). The disc is also attached at the back by connective tissue that is much like a rubber band and pulls the disc back as the condyle moves backward in the glenoid fossa (when you are closing your mouth). In other words, this attachment can stretch and recoil as the jaw opens and closes. Since the disc is a separate structure and may move independently from the condyle, it can be displaced causing many problems. We call this disorder an internal derangement of the TM joint. Internal derangement of the TM joint can be a distressing syndrome of pain, limited jaw movement, clicking, popping and crepitus (a grating sound similar to the crumpling sound of parchment paper) in the TM joint.

This derangement may be caused by genetic pathological changes in the TM joint or acquired pathological changes as a result of trauma. Trauma can be something such large and memorable such as a blow to the head, an impact from a fall, whiplash or sports injury or from micro-trauma which is caused by clenching and/or grinding of the teeth, especially during sleep. Often, internal derangement of the TM joint is preceded by myofascial pain dysfunction that can involve moderate to severe spasms of the muscles of the head, neck, shoulder and/or back. A wide range of symptoms may occur such as headaches, muscle pain, ear pain, dizziness, stuffiness, and ringing in the ears, blurred vision etc. Treatment of these conditions need to be highly individualized and may include a combination of medical and dental therapies. Treatment of your particular problem will be determined by your specific diagnosis.

(As stated by the American Academy of Craniofacial Pain)