It is still perfectly possible to open the mouth. Submucous fibrosis. Fracture of the zygomatic arch. Other causes
Acute osteomyelitis
Ankylosis of the TMJ (fibrous or bony)
Condylar fracture or other trauma. Gaucher disease which is caused by deficiency of the enzyme glucocerebrosidase. Giant cell arteritis
Sympathomimetic drugs, such as amphetamine, methamphetamine, MDA, MDMA, MDEA, methylphenidate, ethylphenidate, and related substances. Infection
Local anesthesia (dental injections into the infratemporal fossa)
Needle prick to the medial pterygoid muscle
Oral submucous fibrosis. Radiation therapy to the head and neck. Tetanus, also called lockjaw for this reason
Malignant hyperthermia
Malaria severa
Secondary to neuroleptic drug use
Malignant otitis externa
Mumps
Peritonsillar abscess
Retropharyngeal or parapharyngeal abscess
Seizure
Stroke
Toothache

Diagnostic approach
X-ray/CT scan taken from the TMJ to see if there is any damage to the TMJ and surrounding structures. Treatment
Treatment requires treating the underlying condition with dental treatments, speech therapy for swallowing difficulty and mouth opening restrictions, physical therapy, and passive range of motion devices. Additionally, control of symptoms with pain medications (NSAIDs), muscle relaxants, and warm compresses may be used. Splints have been used. History
Historically, the term trismus was used to describe the early effects of tetany, also called "lockjaw". References


== External links ==
The variant Val92Met arose somewhere between 250,000 and 100,000 years ago, long enough for this gene to be carried by humans into central Asia. Arg160Trp is estimated to have arisen around 80,000 years ago while Arg151Cys and Asp294His have been estimated to arise around 30,000 years ago. The wide variation of the MC1R gene exists in people of European descent because of the lack of strong environmental pressures on the gene. The original allele of MC1R is coded for dark skin with a high melanin content in the cells. The high melanin content is protective in areas of high UV light exposure. The need was less as humans moved into higher latitudes where incoming sunlight has lower UV light content. The adaptation of lighter skin is needed so that individuals in higher latitudes can still absorb enough UV for the production of vitamin D.  Freckled individuals tend to tan less and have very light skin, an adaptation to allow individuals that expressed these genes to synthesise sufficient vitamin D.

Types
Ephelides describes a freckle that is flat and light brown or red and fades with a reduction of sun exposure. Ephelides are more common in those with light complexions, although they are found on people with a variety of skin tones. The regular use of sunblock can inhibit their development. Liver spots (also known as sunspots and lentigines) look like large freckles, but they form after years of exposure to the sun. Liver spots are more common in older people.