Trismus is the inability to open the mouth. It results in difficulty eating, drinking, speaking and performing dental hygiene. This symptom can arise in the setting of numerous conditions ranging from temporomandibular joint dislocation to oral cancer. The flow chart provides a good summary of the possible causes of trismus and will surely help in your differential diagnosis when evaluating a patient with trismus. Source: https://www.semanticscholar.org/paper/Trismus%3A-aetiology%2C-differential-diagnosis-and-Dhanrajani-Jonaidel/16f596c3b18dd186b19eadbd04abfbd25106f797