The zygomatic bone, commonly known as the cheekbone, is one of the most prominent structures of the human face. Situated on the upper and outer sides of the face, it is easily felt just below the eyes. This bone gives shape and projection to the cheeks, significantly contributing to facial contour and aesthetics. Its location helps bridge the upper part of the face with the mid-face.
Classification and Identity of the Zygomatic Bone
The zygomatic bone is classified as an irregular bone, a category for bones that do not fit the descriptions of long, short, or flat bones. Its unique, quadrilateral form, with multiple surfaces and processes, makes the irregular classification appropriate. It is also identified as a paired bone, meaning there are two in the human skull, one on the right side and one on the left side of the face.
As a core component of the facial skeleton, the zygomatic bone is sometimes referred to as the malar bone or zygoma. Its complex shape allows it to join multiple adjacent bones while also forming parts of three different cranial fossae. The zygomatic bones are characterized as stationary bones; they do not move independently but provide a stable foundation for the surrounding soft tissues and muscles.
Structural Role and Function in the Skull
The primary structural role of the zygomatic bone is to provide the lateral projection that creates the prominence of the cheek. It acts as a lateral buttress for the midface, helping to absorb and distribute forces from trauma. The bone’s robust nature provides resilience and stability to the facial structure, especially during impacts. The zygomatic complex is involved in withstanding forces generated during mastication (chewing) by transmitting forces from the maxilla upward.
A major functional contribution is the protection of the orbit (eye socket), as the zygomatic bone forms a significant portion of its lateral wall and floor. By forming the inferolateral circumference of the orbital margin, it shields the eyeball and surrounding tissues from external pressure. The bone serves as an attachment point for several facial muscles, including the masseter muscle, which closes the jaw during chewing. The stability provided by the zygomatic bone is also necessary for motions associated with speaking, facial expressions, and drinking.
Key Anatomical Features and Articulations
The zygomatic bone features several projections, known as processes, that allow it to connect with other bones in the skull. The temporal process extends backward to meet the zygomatic process of the temporal bone, forming the complete zygomatic arch. This arch is a slender bridge of bone that provides an attachment area for the temporalis muscle.
Extending upward, the frontal process articulates with the frontal bone, securing the cheekbone near the outer edge of the eye socket. The maxillary process projects medially and inferiorly, joining the maxilla (upper jaw) and contributing to the orbital floor. The zygomatic bone articulates with a total of four bones: the frontal bone, the temporal bone, the maxilla, and the sphenoid bone.
These articulations lock the zygomatic bone into place, forming the frontozygomatic, temporozygomatic, and zygomaticomaxillary sutures. The connection with the sphenoid bone occurs at the orbital surface, where the zygoma meets the greater wing of the sphenoid, stabilizing the lateral wall of the eye socket. This network of connections ensures the structural integrity of the mid-face, providing a stable foundation for the orbit and the muscles of mastication.