The maxilla is a major, paired bone complex that forms a significant portion of the facial skeleton, supporting the overlying soft tissues. Fusing at the midline, it is central to the structure that defines the human face and connects to numerous other skull bones. Understanding its location is key to appreciating its extensive role in functions like breathing, speaking, and chewing.
Where is the Maxillary Bone Located
The maxilla forms the upper jaw, positioned superiorly to the mandible. It is comprised of two symmetrical maxillary bones that join together at the midline, a seam known as the intermaxillary suture. Unlike the lower jaw, the maxilla is a fixed, non-mobile structure that is firmly fused to the surrounding bones of the skull. This central position below the eyes and nose defines the shape and contours of the mid-face. The maxilla contributes to the boundaries of the nasal cavity, the eye sockets (orbits), and the oral cavity.
Functions of the Upper Jaw
The upper jaw supports the upper row of teeth. The alveolar process, a thick ridge of bone along the inferior border of the maxilla, provides the bony sockets that anchor the upper dentition. This stable base facilitates the grinding action of chewing when the movable lower jaw presses food against the fixed upper teeth. Forces generated during mastication are transferred to the cranium through the maxilla’s connections with the frontal and zygomatic bones.
The maxilla significantly shapes three major facial cavities. It forms the floor of the orbit, which cradles the eye, and contributes to the lateral walls and floor of the nasal cavity. The palatine process of the maxilla extends horizontally backward to form the anterior two-thirds of the hard palate, which separates the oral cavity from the nasal cavity.
Contained within the body of the maxilla are the maxillary sinuses, which are the largest of the paranasal sinuses. These air-filled spaces contribute to the lightness of the skull and play a role in breathing by moistening and warming inhaled air. They also function as resonance chambers, helping to increase the volume and depth of the voice. This structure is integral to both structural support and physiological processes.
Distinguishing the Maxilla from the Mandible
The mandible is clearly defined as the lower jawbone, supporting the lower set of teeth. The most apparent difference is their respective mobility: the maxilla is immobile and fixed to the skull, while the mandible is the only movable bone of the skull. This movement is made possible by the temporomandibular joint (TMJ), which connects the mandible to the temporal bone of the skull, allowing for opening, closing, and side-to-side movements for biting and speaking.
The maxilla and mandible also differ in their developmental origins. The maxilla primarily forms through intramembranous ossification from the maxillary prominence. The mandible also develops largely through intramembranous ossification, but its formation occurs lateral to Meckel’s cartilage.
Both bones hold teeth, with the maxilla securing the upper teeth and the mandible securing the lower teeth. The mandible, being a single U-shaped bone in adults, is generally larger and stronger to withstand the forces of chewing.