TMJ Disorder: Basic Anatomy of The Jaw Joint

The temporomandibular joints (TMJs) are the jaw joints. Dysfunction of the TMJ can cause a lifetime of chronic illness and pain. This is the basic anatomy of the temporomandibular joint, including video examples of jaw joint dysfunction.

The jaw joints affect a dynamic network of muscles, bones, tissue, tendons, ligaments, nerves, and blood vessels. Symptoms of TMJ disorder may mimic those of other conditions, such as sinusitis, migraine, toothache, stiff muscles, earache, nerve disorders or joint disease.

Because it’s considered a dental condition, doctors often misdiagnose TMJ disorder. If you’re not sure, take the TMJ self-test here.

Anatomy of the Temporomandibular Joint (TMJ)

In the image below, you can see how the jaw bone (mandible) fits into the upper portion of the skull (temporal bone), in relation to surrounding bones and tissue.

(above pic based on Gray’s Anatomy, adapted by Dr. Frank Gillard).

The jawbone branches into two prongs. The first prong sits just under the cheekbone (zygomatic arch). The rear prong (condyle) fits into a small, smooth hollow in the temporal bone, in front of the ear canal (external acoustic meatus).

A flexible disc, known as the articular disc, sits between the condyle and the temporal bone, surrounded by two fluid-filled cavities. This small pad of cartilege attaches to surrounding tissue. The articular disc glides in harmony with the motion and rotation of the mandible, allowing flexible movement of the jaw.

In TMJ disorder, the articular disc becomes displaced and/or damaged. Causes of disc displacement or damage include misalignment of the jaw due to physical trauma, emotional stress, or degenerative bone disease. A displaced disc causes the clicking and popping sounds characteristic of TMJ dysfunction. The following two videos illustrate the mechanisms of healthy and damaged temporomandibular joints.

TMJ Anatomy – Video #1

The video below (English, with Spanish subtitles) shows the movement of the TMJ and the articulated disc, and explains further anatomical details of the TMJ.

TMJ Anatomy – Video #2

The “Yoint” Video, created by two Swedish scientists, shows close-up footage of healthy TMJ and disc movement, followed by several examples of an unhealthy TMJ and articulated disc. This video is not for the squeamish.

In broad terms, “TMJ disorder” refers not only to dysfunction of the TMJ. TMJ disorder also includes disorders of the nerves, bones, muscles, ligaments, tissues, tendons and blood vessels affected by dysfunction of the jaw joint.

TMJ disorder can develop over the course of years. Even a slight misalignment of the jaw joint or damage to the articulated disc can lead to a lifetime of chronic pain and a wide range of health problems. The good news is that TMJ can be treated. Speak to your dentist or health practitioner for effective TMJ treatment options.

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