(1) Tetanus Explanation: Locked jaw syndrome is a disorder that is related to our jaw joint. It causes severe pain and sometimes cannot open the mouth. Tetanus, commonly called locked jaw, is a bacterial disease that affects the nervous system. Persons who have not been vaccinated adequately against tetanus are the most likely to get the disease. Tetanus occurs more Often in older people who have not received adequate booster doses of vaccine and in agricultural workers where Contact with animal manure is more likely.