The mandible, commonly known as the lower jawbone, is the only movable bone in the human skull, apart from the tiny bones of the middle ear. It forms the lower portion of the face, contributing to facial contour and stability. This bone is fundamental for various daily activities.
Anatomy of the Mandible
The mandible is the largest and strongest bone of the human face. It is a single, horseshoe-shaped bone that forms the lower jaw and holds the lower teeth. The “left mandible” refers to the left half of this bone, which typically fuses from two halves during the first year of life.
The mandible consists of a horizontal body and two vertical extensions called rami. The body contains sockets for the lower teeth. The two rami extend upwards from the body, meeting at the angle of the mandible. Each ramus divides into two processes: the coronoid process and the condylar process. The condylar process ends in the mandibular condyle, which articulates with the temporal bone of the skull, forming the temporomandibular joint (TMJ).
Functional Role of the Mandible
The mandible’s mobility, facilitated by the temporomandibular joints (TMJs), enables several bodily functions. These joints allow the jaw to move in various directions: up, down, side to side, and forward and backward.
The mandible is important for mastication, or chewing, working in opposition to the maxilla, or upper jaw. Powerful muscles attached to the mandible facilitate biting and grinding food. Beyond eating, the mandible also plays a role in speech articulation, allowing for the formation of various sounds. Its movements contribute to facial expressions, adding to non-verbal communication.
Common Conditions Affecting the Mandible
A variety of conditions can affect the mandible, often leading to pain or restricted movement. Temporomandibular joint (TMJ) disorders are a common reason for jaw pain, impacting the joints and muscles that control jaw movement. Symptoms of TMJ disorders include:
Pain in the jaw or face
Headaches
Jaw stiffness
Clicking or popping sounds when moving the jaw
Difficulty opening or closing the mouth
These disorders affect up to 12 million people in the U.S., commonly between the ages of 20 and 40, with females being twice as likely to experience them.
Causes of TMJ disorders vary, but can include jaw injury, teeth grinding or clenching (bruxism), arthritis in the jaw joint, or a misaligned bite. Stress is also a contributing factor, as it can lead to jaw tension. Beyond TMJ disorders, the mandible can also be affected by fractures (broken bones) or dislocations (where the jawbone moves out of its joint). Dental issues, such as abscessed teeth or severe infections, can also cause jaw pain. Impacted wisdom teeth can also exert pressure, leading to localized pain.
Addressing Mandible Concerns
When experiencing persistent jaw pain or dysfunction, seeking professional medical evaluation is important. A healthcare provider will begin by discussing symptoms and observing the jaw’s range of motion. They may also palpate areas around the jaw to identify points of tenderness or abnormalities.
To gain a clearer picture of the issue, imaging studies may be recommended:
Dental X-rays provide a general view of the teeth and jaw.
Computed tomography (CT) scans offer detailed images of the bones within the temporomandibular joint.
Magnetic resonance imaging (MRI) is used for assessing the joint’s disc or surrounding soft tissues, identifying issues like disc displacement or inflammation.
TMJ arthroscopy, a minimally invasive procedure involving a small camera, may be used for both diagnosis and treatment.
Treatment approaches for mandible concerns vary based on the specific condition and its severity. Conservative management is the first line of treatment and may include pain relief medications, applying heat or ice, and physical therapy exercises to stretch and strengthen jaw muscles. Oral splints or mouthguards are devices that fit over the teeth to help relax the jaw and improve its function for those who grind or clench their teeth. For more complex or persistent issues, other interventions like corticosteroid injections into the joint or surgical procedures may be considered.