Temporomandibular joint dysfunction (
TMD or
TMJD), also officially known as
temporomandibular joint dysfunction syndrome and
temporomandibular disorder among others, and colloquially referred to as
TMJ and
lockjaw (but this can also refer to other medical conditions with a locked jaw called
trismus, including
tetanus), is an
umbrella term covering
pain and dysfunction of the
muscles of mastication (the muscles that move the jaw) and the
temporomandibular joints (the joints which connect the
mandible to the
skull). The most important feature is pain, followed by restricted mandibular movement, and noises from the temporomandibular joints (TMJ) during jaw movement. Although TMD is not life-threatening, it can be detrimental to
quality of life, because the symptoms can become chronic and difficult to manage. About 20% to 30% of the adult population are affected to some degree. Usually people affected by TMD are between 20 and 40 years of age, and it is more common in females than males. TMD is the second most frequent cause of
orofacial pain after dental pain (i.e.
toothache).