الفهرس 
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Abstract
Temporomandibular Joint (TMJ) is the articulation between the condyle of the mandible and the squamous portion of the temporal bone.
Signs and symptoms of Temporomandibular Disorders (TMDs) are mainly muscular pain (especially in the masseter and temporalis muscles), and articular pain in the form of mouth opening limitation and joint sounds. TMDs symptoms generally fluctuate overtime and correlate significantly with masticatory muscle tension, tooth clenching, grinding, and other oral parafunctional habits. TMDs symptoms are also significantly correlated with an increase in psychosocial factors e.g. worry and stress.
TMDs can cause other symptoms that are beyond the masticatory musculoskeletal system e.g. non-otologic otalgia (ear pain that is not caused by the ear), dizziness, tinnitus, neck pain and toothache. TMDs can contribute to migraine and tension headaches, myofacial pain in the region and many other pain complaints.
Temporomandibular joint can affect ear structures due to pressure on the petrotympanic fissure and tympanic bone that separates that jaw joint from the external auditory canal. Because the chorda tympani nerve (which passes through a fissure in the TMJ capsule) innervates sensation to the tongue, there also may be sensitivity in certain areas of that organ.
In 1930s, Costen, an otolaryngologist, brought TMJ into the awareness of physicians and entists, and readers may still find TMDs occasionally referred to as Costen’s syndrome. TMJ pain and secondary otologic symptoms could be reduced with alterations of the occlusion.
TMJ pain is generally one of four reasons:
1- The most common cause of TMJ pain is myofacial pain dysfunction syndrome, primarily involving the muscles of mastication.
2- Internal derangement is defined as abnormal relationship of disc to any of the other components of the TMJ.
3- Degenerative joint disease, otherwise known as osteoarthritis.
4- TMJ pain remains one of the most reliable diagnostic criteria for temporal arthritis.
Other pathologic conditions may affect TMJ function causing pain and swelling such as chondrosarcoma. Pain is the most common reason that makes patients seeking treatment.
The location of TMJ pain helps in diagnosis, the pain in TMDs is centered immediately in front of the tragus of the ear and projects to the ear, temple, and cheek and along the mandible.
TMJ pain may be misdiagnosed with:
1- Giant cell arteritis (temporal arteritis).
2- Cardiac pain.
3- Dental problems.
4- Trigeminal neuralgia.
5- Migraine and other causes of headache.
6- Herpes zoster.
7- Other ENT disorders and ENT neoplasms.
Pain associated with internal derangement of the TMJ disorders 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 disc snaps into place when the jaw moves. In addition, the chewing muscles may spasm, not function efficiently, and cause pain and tenderness.
Because TMJ symptoms often develop in the head and neck, otolaryngologists are involved in diagnosis and management of such problems.