The temporomandibular joint, or TMJ, is the jaw joint located in front of the ear where the skull & the lower jaw meet.  The lower jaw has 2 joints, obviously, the right & left.  These joints allow the lower jaw (mandible) to open & close.  Each TMJ is a "ball & socket" type joint.  The ball is called a condyle & is located at the head of the mandible.  The socket is
called the articular fossae & is located on the temporal bone at the base of the skull.  Located between the condyle & fossae is a piece of cartilage called a disc or meniscus.  The disc acts as a pillow or cushion between the condyle & fossae to prevent bone on bone rubbing.  When the jaw opens, the condyle slides along the underside of the disc & in a healthy joint, the sliding motion is quite smooth.  The posterior disc attachment consists mostly of small blood vessels & nerves & can be quite pain sensitive.  Other important structures include the ligaments which assist in holding the disc & condyle properly within the fossae.  The muscles that attach the jaw to the skull & those surrounding the TMJ function to move the jaw & jaw joint during chewing & speaking motions.  They are extremely important to proper TMJ function.

The teeth are also important for proper TMJ function.  When the teeth close together or articulate the bite force is carried largely by the teeth themselves.  When there are missing teeth or in certain facial skeletal (orthognathic) deformities the articulation of the teeth is not proper & the jaw  joints (TMJ's) may carry a much larger portion of the bite force causing injury to the joints.
In some cases of TMJ disorder, the disc is displaced, which removes the cushioning effect between the "ball" and "socket" and can result in tenderness and pain in the joint. Stresses can be generated to displace or damage the disc, ligaments & boney surfaces of the condyles & fossae.  In certain patients, these injuries may lead to degenerative arthritis within the jaw joints.
 Muscle imbalances & spasms may be a result of or caused by injuries to the jaw joints.  Facial trauma may also damage the TMJ & impair proper function.

Signs & symptoms of TMJ dysfunction include:

• chronic headaches primarily in the temporal regions (temples).  This is usually indicative of muscle fatigue & spasm.
• clicking, popping or grinding in the jaw joints is indicative of injury to the disc apparatus.
• ear pain, if not caused by problems in the ear itself may be as a result of swelling or injury to the TMJ located immediately in front of the middle ear.
• jaw fatigue & limitation of opening usually indicate muscle dysfunction.
• other pain referral patterns include neck pain, eye pain, sinus pain, tooth pain.
• clenching or persistent grinding of the teeth may be a sign of & cause TMJ problems.
• TMJ dysfunction is most often chronic pain, in many ways similar to chronic low back pain. It involves joints, muscles & ligaments & has times when it is worse than others.