Mandible

From ArticleWorld

The mandible is essentially the only moveable bone in the skull. It is the largest of the facial bone and carries the most strength. The chin and jaw line are shaped by the mandible. The lower teeth all imbed within the mandible.

Anatomy

The mandible is a horseshoe-shaped bone with a somewhat flat ramus that goes up the side of the cheek area. The ramus itself has two projections. The most posterior projection is called the condyloid process, which has a small ball-shaped end that forms the articulation with the temporal bone just in front of the ear. The joint is called the temporomandibular joint. The more anterior process is called the coronoid process. It is the connection point for several facial muscles.

The external surface of the mandible has the mental tubercle, a central, frontal protuberance that gives each person their distinctive-appearing chin. The internal concave surface has two small projections on either side of the midline that project under the mouth and connect to the glenioglossus muscle. Beneath the insertion of the glenioglossus muscle, two other spines attach the gleniohyoid muscle.

The upper border of the mandible is also called the alveolar border. All of the lower teeth attach to this border.

Function

As the mandible is the only truly moveable bone in the face, it has many muscular attachments for the purposes of opening and closing the mouth and for the complex act of chewing. The masseter muscle attaches in multiple places along the lateral mandible and the temporalis muscle inserts onto the lateral surface of the coronoid process. Multiple other muscles that both shape the face and allow for mandibular movement are attached to all but the alveolar surface of the mandible.

Conditions

The mandible is rarely fractured unless there is severe trauma, such as in an automobile accident or an altercation. The site of fracture is commonly in the area of the ramus, where the bone is at its thinnest.

The temporomandibular joint can also become damaged. If an individual grinds his or her teeth or has a misalignment of the teeth, the joint can become inflamed or can wear down its articular cartilage. In some cases the joint must be replaced.