What causes lock jaw?

Lockjaw: Most common cause of lockjaw (trismus) is inflammation of soft tissue around impacted third molar tooth (lower wisdom teeth). Other causes can be inflammation of muscles of mastication (chewing) after removal of wisdom teeth, peritonsillar abscess (around inflamed tonsils), tmj, or rarely result of use of stimulants to treat adhd.

Classically, lockjaw: Is a term for tetanus but it can be used for disease of the TMJ joint of the jaw.

Tmj: Many things can cause the jaw to lock such as disk problems in the jaw joint, arthritis, fracture of the joint, jaw muscle issues, multiple surgeries on the joint and pathology/growth in the joints. See a dentist for an evaluation.

A few things: True "lockjaw" is from tetanus bacteria entering your body: Spasms and stiffness in your jaw muscles, stiffness of your neck muscles, difficulty swallowing, stiffness of your abdominal muscles. I'm assuming you mean you jaw stuck. Can either be do jaw out of socket or problem with disk in jaw joint. In any event, see an oral surgeon to help you with diagnosis and treatment.