Anterior dislocation shifts the lower jaw forward if the mouth excessively opens. This type of dislocation may happen bilaterally or unilaterally after yawning. The muscles that are affected during anterior jaw dislocation are the masseter and temporalis which pull up on the mandible and the lateral pterygoid which relaxes the mandibular condyle. The condyle can get locked in front of the articular eminence. Posterior dislocation is possible for people who get injured by being punched in the chin. This dislocation will push the jaw back affecting the alignment of the mandibular condyle and mastoid. The external auditory canal may be fractured. Superior dislocations occur after being punched below the mandibular ramus as the mouth remains half-open. Since great force occurs in a punch, the angle of the jaw will be forced upward moving towards the condylar head. This can result in a fracture of the glenoid fossa and displacement of the condyle into the middle cranial fossa, potentially injuring the facial and vestibulocochlear nerves and the temporal lobe. Lateral dislocations move the mandibular condyle away from the skull and are likely to happen together with jaw fractures.Posterior, superior and lateral dislocations are uncommon injuries and usually result from high-energy trauma to the chin. By contrast, anterior dislocations are more often the result of low-energy trauma (e.g. tooth extraction) or secondary to a medical condition that affects the stability of the joint (e.g. seizures, ligamentous laxity, degeneration of joint capsule). Diagnosis
As with other joint dislocations, clinical history and examination are crucial for diagnosis of a jaw dislocation.
Lethal midline granuloma (LMG) is an historical term for a condition in which necrotic and highly destructive lesions develop progressively in the middle of the face, principally the nose and palate. Many cases presented with ulcerations in or perforations of the palate. LMG was thought to be a manifestation of three or four different diseases: the well-characterized disease of granulomatosis with polyangiitis, the ill-defined disorders of polymorphic reticulosis or mid-line malignant reticulosis, and an incompletely defined form of non-Hodgkins lymphoma. Subsequent studies found that the cells infiltrating the midline tissues in cases of lethal midline granuloma that were not clearly diagnosed as granulomatosis with polyangiitis were: a) infected by the Epstein-Barr virus and b) consisted of malignant lymphocytes, usually NK cells or, rarely, cytotoxic T cells. The disease is therefore now regarded as a NK/T cell malignancy, is grouped with other Epstein-Barr virus-associated lymphoproliferative diseases and is classified by the World Health Organization (2017 update) as a manifestation of the well-defined disease, extranodal NK/T-cell lymphoma, nasal type (ENKTCL-NT). ENKTCL-NT is a rare type of lymphoma that commonly involves the nasal cavity, oral cavity, and/or pharynx but less commonly can also involve the eye, larynx, lung, gastrointestinal tract, skin, and various other tissues. Patients presenting with highly localized midline facial disease fit the historical definition of lethal midline granuloma. These cases, unlike other cases ENKTCL-NT that have more widespread disease, often show no or relatively little progression of their disease over long periods of time.