The mandible, commonly known as the lower jawbone, is the largest and strongest bone in the human face. It anchors the lower set of teeth and shapes the contour of the lower third of the face. Its strength is necessary for withstanding the forces generated by the powerful muscles involved in jaw movement.
Where the Mandible Is
The mandible is situated beneath the maxilla (upper jaw) in the facial skeleton. It is the only bone of the skull capable of significant movement, which allows for the wide range of motions necessary for daily functions.
It connects to the rest of the skull via the bilateral temporomandibular joints (TMJs). The TMJ is an articulation where the posterior projection of the mandible meets the temporal bone, located just in front of the external ear canal.
The head of the condylar process fits into the mandibular fossa, a depression on the temporal bone. Ligaments and an articular disc stabilize the articulation, cushioning the bone surfaces. This joint enables the jaw to hinge, glide, and perform lateral movements.
Structure and Key Features
The mandible consists of a horizontal body and two vertical extensions called rami. The body is the curved, anterior section that holds the lower teeth in sockets along its superior edge, known as the alveolar process. The chin is formed by the mental protuberance, a thickened projection at the center of the body.
The rami project upward from the posterior ends, meeting the body at the angle of the mandible. Each ramus terminates superiorly in two projections separated by the mandibular notch. The anterior projection is the coronoid process, an attachment site for the temporalis muscle.
The posterior projection is the condylar process, topped by the condyle, which forms the movable part of the TMJ. The bone also contains passages like the mandibular foramen and the mental foramen. These openings allow nerves and blood vessels to supply the teeth and soft tissues of the lower face.
Primary Functions
The mandible’s primary role is to facilitate mastication (chewing food). Powerful muscles, including the masseter and temporalis, attach to the mandible and generate the force required to break down food against the upper teeth. The coordinated movements of the TMJ allow the jaw to perform both hinge and grinding motions.
The mandible is also necessary for proper articulation during speech. Precise movements of the lower jaw allow for the formation of various sounds and syllables. Without the ability to move the jaw in conjunction with the tongue and lips, clear vocal communication would be compromised.
The mandible serves as the support structure for the lower dental arch. The alveolar process contains the sockets that anchor the roots of the lower teeth, securing them firmly in place. This support is integral to maintaining the correct alignment of the teeth.