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The tempormandibular joint (TMJ) is a very complex joint. It functions to open and close the jaw, move the jaw to the right and left, as well as move in a forward and backward direction. This wide range of motion allows speech, yawning, as well as biting and chewing food. These various movements are the result of a uniquely designed joint.
The TMJ is actually the first of the body’s joints encountered proceeding in a head to feet direction. The TMJ is made up of 2 boney parts, the condylar process of the mandible and the glenoid fossa of the skulls temporal bone. In between the condyle and the glenoid fossa is the articular disc which is made up of soft cartilage. The disc is held in place by ligaments and muscles attaching it to both the condyle and the glenoid fossa. Posterior or behind the disc is vascular and nerve tissue.
In a TMJ that is quiet, as the mouth opens, the condyle rotates and moves down and forward from the glenoid fossa. Small muscles pull the disc down and forward keeping the disc in place between the condyle and the skull. When the mouth closes, the disc slides back along with the condyle into its normal position in the fossa. No joint noises are evident.
In a joint where the condyle is positioned in a posterior or pushed back retruded position, there may not be room for the disc between the condyle and the fossa. In this case the disc may be pushed in front of or to the side of the condyle. As the mouth opens and the condyle comes down and forward, room develops for the disc. Muscles and ligaments attached to the disc snap it into place. This snapping motion often creates a joint sound known as a click or pop that may be loud enough to be heard by others. As the mouth closes the disc is once again pushed out of the way and may make yet another click or popping sound. This is a traumatic event for the joint and eventually can cause irreversible damage by tearing or perforating the joint disc.
Another sound that is not uncommon coming from the TMJ is crepitus. Crepitus is often described as a grating sandpaper like sound. Crepitus is associated with arthritic changes in the joint and often with a perforation of the disc allowing bone-to-bone contact when the mouth opens and closes.
When joint sounds are evident it is most often associated with a retruded mandible where the condyles are posteriorly positioned. Although joint sounds are not always accompanied by pain they can be an indicator of TMJ disorder symptoms in the future such as migraines, headaches, vertigo, and ear congestion. Joint sounds can also be a predictor of airway obstruction and Obstructive Sleep Apnea (OSA). Physiologic Neuromuscular Dentistry offers a predictable solution for those joints that click and pop throughout the day.