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Zygomatic

Other Terms: Cheek bone, Orbital bone, Malar bone, Os zygomaticum, Os zygomatique

Type

irregular

Description

This yoke-shaped bone has three distinct surfaces, five borders, and two processes. It is situated anterolateral on the face as the "cheekbone," contributing to the lateral and inferior walls of the orbit. It consists of external and internal laminae of compact bone with an inner core of spongy bone.

Etymology

This bone, originally named by Galen the os zygoma, comes from the Greek word zygon meaning yoke after its resemblance to a yoke placed on oxen.

Articulations

The zygomatic bone articulates with four bones: the frontal, the sphenoid, the temporal, and the maxillary bones. A strong, thick buttress of bone arises vertically to form a deeply serrate articulation with the lateral base of the supra-orbital margin of the frontal bone. A thinner process is directed posteriorly to form a serrate suture with the zygomatic process of the temporal bone. The two medially directed margins of the bone form more extensive articulations with the sphenoid and maxillary bones.

Ossification

Beginning in the second month, the zygomatic bone begins to ossify intramembranously from one to three centers. Typically the centers have fused into a single center by the third month, therefore many authors often report that the bone ossifies from one center. This single center is situated laterally just beneath the orbit. By birth the bone is contacting neighboring bones. Sometimes the bone remains divided by a horizontal suture, the smaller, lower element forming the so-called os japonicum.

Latin

Os zygomaticum

French

Os zygomatique

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