The term temporomandibular disorders is an umbrella term for a group of musculoskeletal and neuromuscular conditions that involve the temporomandibular joint (TMJ), the masticatory muscles, and all associated structures. Temporomandibular disorders often present with pain in the jaw, face, and neck and/or with dysfunction of the jaw joint (often decreased range of motion) and is often accompanied by headache Approach to the Patient With Headache Headache is pain in any part of the head, including the scalp, face (including the orbitotemporal area), and interior of the head. Headache is one of the most common reasons patients seek medical... read more or ear pain. People are considered to have a temporomandibular disorder when the pain or dysfunction is severe enough to make them seek professional care.
Temporomandibular disorders typically are multifactorial in origin, but most are related to problems with masticatory muscles and ligaments of the temporomandibular joints or internal derangements within the joints themselves. Joint hypermobility can also contribute.
Internal derangements of the TMJ Internal Temporomandibular Joint (TMJ) Derangement The most common form of internal temporomandibular joint derangement is an anterior displacement of the articular disk in relation to the condyle. Often, joint pain and popping/clicking occur... read more are a result of altered or disturbed movement of the mandibular condyle in the glenoid fossa or against the articular disk (see figure The temporomandibular joint The temporomandibular joint 
). The disk, which is composed of dense fibrous connective tissue and shaped like a mature red blood cell, serves as a cushion between the bone surfaces. Unlike most joints, which are lined with hyaline cartilage, the TMJ bone surfaces are lined with fibrocartilage. Causes for the altered or disturbed movement include direct or indirect macrotrauma (eg, flexion-extension injury of the neck—also known as whiplash—which can cause referred pain), microtrauma (eg, due to parafunctional behaviors such as awake/sleep clenching and grinding of the teeth Bruxism Bruxism is clenching or grinding of teeth. Bruxism can occur during sleep (sleep bruxism) and while awake (awake bruxism). In some people, bruxism causes headaches, neck pain, and/or jaw pain... read more or persistent gum chewing), systemic disorders (eg, rheumatoid arthritis Rheumatoid Arthritis (RA) Rheumatoid arthritis is a chronic systemic autoimmune disease that primarily involves the joints. Rheumatoid arthritis causes damage mediated by cytokines, chemokines, and metalloproteases.... read more 
or other autoimmune/connective tissue disorders), local or systemic infections, and acute malocclusion Malocclusion Malocclusion is abnormal contact between the maxillary and mandibular teeth. (See also Evaluation of the Dental Patient.) This photo shows misalignment between upper and lower teeth as the jaw... read more 
.
(See also Mandibular Dislocation Mandibular Dislocation Mandibular dislocation is just one of several dental emergencies that require immediate treatment. Spontaneous mandibular dislocation usually occurs in people with a history of such dislocations... read more , Temporal Bone Fractures Temporal Bone Fractures Temporal bone fractures can occur after severe blunt trauma to the head and sometimes involve structures of the ear, causing hearing loss, vertigo, balance disturbance, or facial paralysis.... read more 
and Jaw Tumors Jaw Tumors Numerous tumor types, both benign and malignant, originate in the jaw. Symptoms are swelling, pain, tenderness, and unexplained tooth mobility; some tumors are discovered on routine dental x-rays... read more 
.)
The temporomandibular joint
The joint is formed by the mandibular condyle and the glenoid fossa of the temporal bone; a fibrocartilaginous articular disk functions as a cushion between the joint surfaces.  |
Diagnosis of Temporomandibular Disorders
Clinical evaluation
Disorders of the temporomandibular joint (TMJ) must be distinguished from the many conditions that mimic them (see table Some Conditions That Mimic Temporomandibular Disorders Some Conditions That Mimic Temporomandibular Disorders 
). Pain exacerbated by finger pressure on the joint when the mouth is opened implicates the TMJ.
Patients are asked to describe the pain and designate painful areas. Muscles of mastication (temporalis, masseter, and medial pterygoids) and the cervical and occipital muscles are palpated for general tenderness and trigger points (spots that radiate pain to another area). The lateral pterygoids cannot be directly palpated.
Patients are observed opening the mouth as wide as is comfortable. When patients open their mouth, the mandible typically deviates toward the painful side. Palpation and auscultation of the joint during opening and closing may reveal tenderness and catching and intracapsular sounds such as clicking/popping or crepitus.
Condylar motion can best be palpated by bilaterally placing the middle fingers on the preauricular areas (lateral poles of the condyle) and exerting gentle medial pressure or by placing the 5th fingers into the external ear canals and exerting very gentle forward pressure as patients move their jaw. The average-sized patient can open the mouth at least 40 mm (measured between the incisal edges of the upper and lower central incisors). To account for differences in patient size, a patient should be able to fit 3 fingers (index, middle, ring) into the mouth up to the distal interphalangeal joints.
