You may not have heard of it, but you use it hundreds of times every day. It is the Temporo-Mandibular Joint (TMJ), the joint where the mandible (the lower jaw) joins the temporal bone of the skull, immediately in front of the ear on each side of your head. A small disc of cartilage separates the bones, much like in the knee joint, so that the mandible may slide easily; each time you chew you move it. But you also move it every time you talk and each time you swallow (every three minutes or so). It is, therefore, one of the most frequently used of all joints of the body and one of the most complex.

Gray309_smallTMJ stands for Temporo-Mandibular Joint, or the jaw joint. In fact, there are really two TMJs, one in front of each ear. The TMJ is the joint formed by the temporal bone of the skull (Temporo) with the lower jaw or mandible (hence, mandibular).

These joints move each time we chew, talk or even swallow. The TMJ is actually a sliding joint and not a ball-and-socket like the shoulder. This sliding allows for pressures placed on the joint to bedistributed throughout the joint and not just in one area. The TMJ is the most complex joint in the human body. Placed between these two bones is a disc, just like the one between your back bones. This disc is primarily made of cartilage and in the TMJ acts like a third bone. The disc, being attached to a muscle, actually moves with certain movements of the TMJ.

The nerve to the TMJ is a branch of the trigeminal nerve and therefore, an injury to the TMJ may be confused with neuralgia of the trigeminal nerve. The two bones of the TMJ are held together by a series of ligaments, any of which can be damaged, just like any other joint. A damaged TMJ ligament usually results in a dislocation of the disc, the lower jaw, or both. Also, the bones are connected by two main muscles: the temporalis, the masseter, and a muscle just discovered by Dr. Shankland, the zygomandibular. Any or all of these muscles may be painful and produce pain in the TMJ or at the very least, abnormal movement of the lower jaw.

A malfunction of one or both of these jaw joints can be caused by trauma, whiplash, malocclusion (bad bite), poor posture, teeth grinding or skeletal malformation. Any malfunction prevents the complex system of muscles, bones and joints working together in harmony. The result is TMJ disorder — also known as TMD or CMD (Cranio-Mandibular Dysfunction).

It is estimated that one in every 4 people suffer from one of more TMJ symptoms. Because TMJ is known as the “great impostor” it can be difficult to diagnose without the knowledge of how the jaw joints, muscles, and bones work together. This sliding allows for pressures placed on the joint to bedistributed throughout the joint and not just in one area. The TMJ is the most complex joint in the human body. Placed between these two bones is a disc, just like the one between your back bones. This disc is primarily made of cartilage and in the TMJ acts like a third bone. The disc, being attached to a muscle, actually moves with certain movements of the TMJ.

The nerve to the TMJ is a branch of the trigeminal nerve and therefore, an injury to the TMJ may be confused with neuralgia of the trigeminal nerve. The two bones of the TMJ are held together by a series of ligaments, any of which can be damaged, just like any other joint. A damaged TMJ ligament usually results in a dislocation of the disc, the lower jaw, or both. Also, the bones are connected by two main muscles: the temporalis, the masseter, and a muscle just discovered by Dr. Shankland, the zygomandibular. Any or all of these muscles may be painful and produce pain in the TMJ or at the very least, abnormal movement of the lower jaw.

How Can Things Go Wrong with TMJ?

Gray310_smallIn most patients, pain associated with the TMJ is a result of displacement of the cartilage disc that causes pressure and stretching of the associated sensory nerves. The popping or clicking occurs when the disk snaps into place when the jaw moves. In addition, the chewing muscles may spasm, not function efficiently, and cause pain and tenderness.

Both major and minor trauma to the jaw can significantly contribute to the development of TMJ problems. If you habitually clench, grit, or grind your teeth, you increase the wear on the cartilage lining of the joint, and it doesn’t have a chance to recover. Many persons are unaware that they grind their teeth, unless someone tells them so.

Chewing gum much of the day can cause similar problems. Stress and other psychological factors have also been implicated as contributory factors to TMJ dysfunction. Other causes include teeth that do not fit together properly (improper bite), malpositioned jaws, and arthritis. In certain cases, chronic malposition of the cartilage disc and persistent wear in the cartilage lining of the joint space can cause further damage.