TMD involves the 2 joints that link the lower jaw to the skull. These joints let the mouth open and close. They are in front of your ears.

There are 3 types of TMD:

  • Myofascial pain of the muscles that control jaw function
  • Joint derangement, such as a displaced disc, dislocated jaw, or injury to the bone
  • Arthritis of the temporomandibular joint

Adult Skull Showing Temporomandibular Joint
Adult Skull Showing TMJ and Muscles

Copyright © Nucleus Medical Media, Inc.

You may have TMD if:

  • The temporomandibular joints (TMJ) are often swollen and sore.
  • The muscles that work the joints spasm often.
  • The disc that rests between the joint and the skull is worn out or out of place.
  • You have problems moving your jaw.
  • Your bite is off or not in line.
  • You have clicking in when you move your jaw.

The exact cause of TMD is not known. Some people have had accidents or injuries of the jaw, but many others have not. Some causes may be:

  • Grinding the teeth or clenching the jaw because of stress
  • Arthritis of the joint
  • Past injury or trauma to the joint
  • Facial bone defects
  • A bite that is off or not in line

Enlargement of TMJ With Jaw Open
Enlargement of TMJ with Open Jaw

Copyright © Nucleus Medical Media, Inc.

TMD symptoms may originate within the joint itself or from the muscles that surround the joint. The treatment of these 2 variants of TMD may differ.


Temporomandibular disorders. American Association of Oral and Maxillofacial Surgeons website. Available at: Accessed July 29, 2019.

Temporomandibular disorders. EBSCO DynaMed website. Available at: Updated February 20, 2018. Accessed July 29, 2019.

Temporo-mandibular joint (TMJ) pain. ENThealth—American Academy of Otolaryngology-Head and Neck Surgery website. Available at: Updated January 2019. Accessed July 29, 2019.

TMJ. Mouth Healthy—American Dental Association website. Available at: Accessed July 29, 2019.

TMJ (temporomandibular joint and muscle disorders). National Institute of Dental and Craniofacial Research website. Available at: Accessed July 29, 2019.

Last reviewed June 2019 by EBSCO Medical Review Board Daniel A. Ostrovsky, MD  Last Updated: 10/18/2019