The temporomandibular (tem-puh-roe-man-DIB-u-lur) joint (TMJ) acts like a sliding hinge, connecting your jawbone to your skull. You have one joint on each side of your jaw. TMJ disorders — a type of temporomandibular disorder or TMD — can cause pain in your jaw joint and in the muscles that control jaw movement.

The exact cause of a person's TMJ disorder is often difficult to determine. Your pain may be due to a combination of factors, such as genetics, arthritis or jaw injury. Some people who have jaw pain also tend to clench or grind their teeth (bruxism), although many people habitually clench or grind their teeth and never develop TMJ disorders.

In most cases, the pain and discomfort associated with TMJ disorders is temporary and can be relieved with self-managed care or nonsurgical treatments. Surgery is typically a last resort after conservative measures have failed, but some people with TMJ disorders may benefit from surgical treatments.

Signs and symptoms of TMJ disorders may include:

• Pain or tenderness of your jaw
• Pain in one or both of the temporomandibular joints
• Aching pain in and around your ear
• Difficulty chewing or pain while chewing
• Aching facial pain
• Locking of the joint, making it difficult to open or close your mouth

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 need treatment for a TMJ disorder.

The temporomandibular joint combines a hinge action with sliding motions. The parts of the bones that interact in the joint are covered with cartilage and are separated by a small shock-absorbing disk, which normally keeps the movement smooth.

Painful 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

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