Medical expert of the article
New publications
Temporomandibular joint
Last reviewed: 19.11.2021
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
The temporomandibular joint (art. Temporomandibularis) is the only joint in the region of the skull. This joint is paired, formed by the joint head of the lower jaw, as well as the mandibular fossa and the joint tubercle of the temporal bone, covered with fibrous cartilage. The joint capsule at this joint is wide. On the temporal bone it is attached anterior to the articular tubercle, and behind - near the stony-drum slit. On the condylar process of the lower jaw, the capsule is attached approximately 0.5 cm below the posterior edge of the head of this bone. The joint capsule is fused to the peripheral parts of the articular disc, so the disk divides the joint cavity into two separate sections (floor). The synovial membrane of the temporomandibular joint is also divided into the upper and lower synovial membranes (membranae synoviales superior et inferior) covering the inner surface of the joint capsule of the upper and lower joint floors, respectively.
Temporomandibular joint is strengthened with ligaments. The lateral ligament (lig. Laterale) is the lateral thickening of the capsule. Outside the joint are two ligaments. The wedge-mandibular ligament (lig. Sphenomandibulare) begins on the spine of the sphenoid bone and is attached to the tongue of the lower jaw. The sternomandibular ligament (lig. Stylomandibulare) originates from the styloid process of the temporal bone to the inner surface of the lower jaw, attaching itself near its angle.
Temporomandibular joint is paired, complex (has articular disc, discus articularis), combined, ellipsoidal. In the right and left temporomandibular joints the following types of movements are performed: lowering and lifting of the lower jaw, corresponding to the opening and closing of the mouth. It is possible to push the lower jaw forward and return to its original position; movement of the lower jaw to the right and left (lateral movements).
When lowering the lower jaw, the chin protrusion moves downward and backwards, along an arc turned concavely posteriorly and upward. In this movement, three phases are distinguished. In the first phase (a slight lowering of the lower jaw), movement occurs around the frontal axis in the lower floor of the joint. The joint disc remains in the joint fossa. In the second phase, with a significant lowering of the lower jaw against the background of articular movement of the joints in the lower floor of the joint, the cartilaginous disk, along with the head of the articular process, slides forward, shifting to the articular tubercle. The condylar process of the mandible moves anteriorly approximately 12 mm. In the third phase (maximal lowering of the jaw) movement occurs only in the lower floor of the joint around the frontal axis. The articular disk at this time is located on the articular tubercle. The mechanism of raising the lower jaw repeats in the reverse order the stages of its lowering.
When the mandible is displaced forward, the movement occurs only in the upper floor of the joint. The articular processes along with the articular discs slide forward and extend to the articular tubercle in both the right and left temporomandibular joints.
With lateral displacement of the mandible, the movements in the right and left temporomandibular joints are not the same: when the lower jaw moves to the right in the left temporomandibular joint, the joint head, together with the disc, slides anteriorly and opens onto the joint lump. Slip occurs only in the upper floor of the joint. Simultaneously, in the joint of the right side, the joint is displaced around a vertical axis passing through the neck of the condylar process. When the lower jaw moves to the left, the head slides along with the articular disc forward in the right joint, and the rotation around the vertical axis in the left.
On the x-ray of the temporomandibular joint in the lateral projection (with the oral cavity closed), the mandibular fossa of the temporal bone is seen as a depression. The articular tubercle protrudes forward. The head of the lower jaw has a semi-oval shape with smooth outlines. Between the head of the lower jaw and the mandibular fossa, an x-ray joint gap is visible, wider in the middle than at the edges. When the lower jaw is lowered, the head of the lower jaw is located on the articular tubercle, and the mandibular fossa remains free.