The Maxillomandibular Joint (MMHJ) is an informal but descriptive name for the Temporomandibular Joint (TMJ), which connects the lower jawbone, or mandible, to the skull’s temporal bone. This complex, paired joint facilitates essential daily functions such as speaking, swallowing, and chewing. Because of its constant use, dysfunction is common, affecting millions who experience discomfort or restricted movement, collectively known as Temporomandibular Disorders (TMD).
The Anatomy of the Jaw Joint
The jaw joint is a sophisticated articulation located on either side of the head, just in front of the ear canal. It is formed by the rounded ends of the mandible, called the condyles, fitting into a concave area of the temporal bone known as the glenoid fossa. Separating these two bony surfaces is the articular disc, a fibrous cushion that prevents direct bone-on-bone contact and absorbs shock.
This structure is classified as a ginglymoarthrodial joint, meaning it allows for two distinct types of motion. The lower compartment permits a rotational or hinge movement for the initial opening of the mouth. As the mouth opens wider, the upper compartment facilitates a translational or sliding movement, where the condyle and disc glide forward together along the temporal bone. This combination of rotation and sliding makes the jaw joint one of the most flexible and frequently used joints in the body.
Common Issues Affecting the Maxillomandibular Joint
The most common symptom of TMD is pain in the chewing muscles or the joint itself, which can radiate into the face, neck, or ear. Many people also experience a clicking, popping, or grating sound when moving their jaw, which may signal a displacement of the articular disc.
Contributing factors include physical trauma to the jaw or head, various forms of arthritis, and certain sustained habits. For instance, chronic teeth grinding or clenching, known as bruxism, places excessive force on the joint and surrounding muscles. This sustained strain can lead to muscle fatigue and inflammation, resulting in stiffness and limited ability to fully open or close the mouth.
Diagnosis and Non-Surgical Treatment
A clinician will diagnose an MMHJ issue through a thorough physical examination, palpating the joint and surrounding muscles to check for tenderness or sound during movement. Imaging, such as X-rays, CT scans, or MRI, may be used to visualize the condition of the bony structures and the soft tissues, including the articular disc. An MRI is useful for assessing disc position and joint fluid status.
Initial management focuses on conservative therapies aimed at reducing pain and restoring normal function. Simple measures include applying moist heat or cold packs, eating soft foods, and learning relaxation techniques to lessen jaw tension. Non-prescription anti-inflammatory medications can help manage acute muscle and joint pain. A custom-fitted oral appliance or splint, often worn at night, is used to stabilize the jaw and reduce the effects of grinding. Physical therapy, which includes gentle stretching and strengthening exercises for the jaw muscles, is a recommended treatment component.