TMJ disorders cause tenderness and pain in the temporomandibular joint (TMJ) — the joint on each side of your head in front of your ears, where your lower jawbone meets your skull. This joint allows you to talk, chew and yawn.

Between 5 and 15 percent of people in the United States experience pain associated with TMJ disorders, according to the National Institute of Dental and Craniofacial Research, part of the National Institutes of Health. Women are more likely than men to develop TMJ disorders.

In most cases, pain and discomfort associated with TMJ disorders can be alleviated with self-managed care or nonsurgical treatments, but more-severe cases may need to be treated with dental or surgical interventions.

Signs and symptoms of TMJ disorders may include:

- Pain or tenderness of your jaw
- Aching pain in and around your ear
- Difficulty chewing or discomfort while chewing
- Aching facial pain
- Locking of the joint, making it difficult to open or close your mouth
- Headache
- Uncomfortable bite
- An uneven bite, because one or more teeth are making premature contact

TMJ disorders can also cause a clicking sound or grating sensation when you open your mouth or chew. But if there's no pain or limitation of movement associated with your jaw clicking, you probably don't have a TMJ disorder.

Because it combines a hinge action with sliding motions, the temporomandibular joint is one of the most complex joints in your body. The lower jaw has rounded ends that glide in and out of the joint socket when you talk, chew or yawn. The parts of the bones that interact in the joint are covered with cartilage and are separated by a small shock-absorbing disk, which keeps the movement smooth.

TMJ disorders can occur if:

- The disk erodes or moves out of its proper alignment.
- The joint's cartilage is damaged by arthritis.
- The joint is damaged by a blow or other impact.
- The muscles that stabilize the joint become fatigued from overwork, which can happen if you habitually clench or grind your teeth.

In many cases, however, the cause of TMJ symptoms isn't clear.

TMJ disorders most commonly occur in women between the ages of 30 and 50. Other factors associated with TMJ disorders include:

- Jaw clenching
- Teeth grinding (bruxism)
- Rheumatoid arthritis
- Fibromyalgia
- Facial or jaw trauma
- Congenital deformity of the facial bones