cheekbone n : the arch of bone beneath the eye that forms the prominence of the cheek [syn: zygomatic bone, mala, malar bone, jugal bone, os zygomaticum]
- The small prominent bone of the cheek.
The zygomatic bone came from the latin tearm zyosislymore meaning malar bone (malar bone) is a paired bone of the human skull. It articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. It forms part of the orbit and is commonly referred to as the cheekbone. It is situated at the upper and lateral part of the face: it forms the prominence of the cheek, part of the lateral wall and floor of the orbit, and parts of the temporal and infratemporal fossae [Fig. 1]. It presents a malar and a temporal surface; four processes, the frontosphenoidal, orbital, maxillary, and temporal; and four borders.
SurfacesThe malar surface is convex and perforated near its center by a small aperture, the zygomaticofacial foramen, for the passage of the zygomaticofacial nerve and vessels; below this foramen is a slight elevation, which gives origin to the Zygomaticus.
The temporal surface, directed posteriorly and medially, is concave, presenting medially a rough, triangular area, for articulation with the maxilla (articular surface), and laterally a smooth, concave surface, the upper part of which forms the anterior boundary of the temporal fossa, the lower a part of the infratemporal fossa. Near the center of this surface is the zygomaticotemporal foramen for the transmission of the zygomaticotemporal nerve.
ProcessThe zygomatic process is a protrusion from the rest of the skull, like the bumper of a car. Most of it belongs to the zygomatic bone, but there are other bones contributing to it too, namely the frontal bone, maxilla and temporal bone.
BordersThe antero-superior or orbital border is smooth, concave, and forms a considerable part of the circumference of the orbit.
The antero-inferior or maxillary border is rough, and bevelled at the expense of its inner table, to articulate with the maxilla; near the orbital margin it gives origin to the Quadratus labii superioris.
The postero-superior or temporal border, curved like an italic letter f, is continuous above with the commencement of the temporal line, and below with the upper border of the zygomatic arch; the temporal fascia is attached to it.
The postero-inferior or zygomatic border affords attachment by its rough edge to the Masseter.
OssificationThe zygomatic bone is generally described as ossifying from three centers - one for the malar and two for the orbital portion; these appear about the eighth week and fuse about the fifth month of fetal life.
Mall describes it as being ossified from one center which appears just beneath and to the lateral side of the orbit.
After birth, the bone is sometimes divided by a horizontal suture into an upper larger, and a lower smaller division.
In some quadrumana the zygomatic bone consists of two parts, an orbital and a malar.
ArticulationsThe zygomatic articulates with four bones: the frontal, sphenoidal, temporal, and maxilla.
Image:Orbital_bones.png|The seven bones which articulate to form the orbit. Image:Illu facial bones.jpg|Facial bones.