I have tmj syndrome in my jaw, what causes my jaw to lock up?

Many reasons: There are many reasons for a lock jaw. Please see a dentist or an oral surgeon for a full evaluation.

Non-reducing displac: Usually for patients with a tmd problem, jaw locking is the result of the disc or meniscus, which is the pad between the 2 boney parts of the joint, displacing foreward and/or laterally and keeping the lower jaw from moving foreward and opening fully. Usually lateral movement to one side may be limited also.

Displaced disk: The internal anatomy of the TMJ has a soft tissue disk that prevents bone on bone function. If this is displaced it can get in the way and prevent normal jaw function limiting opening and giving the sensation of a locked jaw.

Two possibilities: The most likely possibility is displacement of the disc that creates a mechanical blocking(locking) of the normal opening path of the condyle(jaw joint). Another possibility, although less likely, is that the muscles that support the joint are splinted (strongly contracted) such that they greatly limit jaw motion and mimic disc displacement. An exam by a specialist in TMJ will provide the answer.

Displaced disk: Your jaw may be locked, which means that the articular disk that joins the upper and lower jaws (maxilla and mandible, ) may be out of place. It may be displaced forward and does not allow the mandible to get back to its comfortable position and the lower teeth therefore do not come together.

Disc or muscle: Most likely the disc is blocking movement. Chronis spasm of muscles possible. See TMJ expert. Any dentist can be a TMJ expert with the proper training and experience. Most commonly, oral surgeons, prosthodontists, and orofacial pain specialists. Ask your MD, your dentist and your dental society for referrals.

Joint Derangement: The most common causes are abnormal jaw mechanics can be due to congenital or acquired asymmetries or to the sequelae of trauma to TMJ or osteoarthritis.