<Tr> <Th> MeSH </Th> <Td> D014313 </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> Trismus, also called lockjaw, is reduced opening of the jaws (limited jaw range of motion). It may be caused by spasm of the muscles of mastication or a variety of other causes . Temporary trismus occurs much more frequently than permanent trismus . It is known to interfere with eating, speaking, and maintaining proper oral hygiene . This interference, specifically with the patient's ability to swallow properly, results in an increased risk of aspiration . In some instances, trismus presents with altered facial appearance . The condition may be distressing and painful for the patient . Examination and treatments requiring access to the oral cavity can be limited, or in some cases impossible, due to the nature of the condition itself . </P> <P> Trismus is defined as painful restriction in opening the mouth due to a muscle spasm, however it can also refer to limited mouth opening of any cause . Another definition of trismus is simply a limitation of movement . Historically and commonly, the term lock jaw was sometimes used as a synonym for both trismus and tetanus . </P>

One of the first signs of the onset of tetanus is trismus also referred to as