In vertebrates, the zygomatic arch is a curved bony protrusion of the skull that extends along the outer edge of the lower eye socket from the temple to the maxilla, or upper jaw. It is more commonly called the cheekbone, but it also is known as the zygoma, or the malar bone. The term "zygomatic" is derived from the Greek word "zugoma," which means bar, bolt or yoke, because the shape of the bony structure resembles that of a yoke used to harness oxen.
The zygomatic arch is located just in front of the ear and is one part of a three-part structure that also includes the orbit — the eye socket — and the temporal bone. The zygomatic arch is connected to the mandible — the lower jaw — at the temporo-mandibular joint and is the origin of the masseter muscle. The whole zygomatic skeletal structure is collectively known as the zygomaticomaxillary complex. Along with being part of the human skull, the zygomatic arch also is present in the skeletal facial structures of other vertebrates such as cats, dogs, horses, cows and more.
Fractures to the zygomatic arch are among the most common facial injuries, second only to nasal fractures in frequency. The most common causes of zygomatic fractures are high-impact traumas such as motor vehicle accidents, sports injuries, assaults and falls. The zygoma connects to the skull in four places, so this type of injury also is called a tetrapod fracture, in which all four connecting points are broken; or a tripod fracture, in which three of the four connecting points are broken. In an isolated zygomatic arch fracture, only one connecting point is broken.
The earliest documented treatment of zygomatic fractures dates to 3000 B.C. Guillaume Dupuytren, Howard Lothrop and William Keen, the pioneers of modern zygomatic facial surgery, practiced their techniques in the 18th and 19th centuries. A traction procedure for zygomatic repair was introduced by Dr. Louis Stroymeyer in 1844 and is still in use today. In 1927, Dr. Harold Gilles began concealing the facial incisions required by the repair of zygomatic fractures in the hairline, thus reducing the prominence of facial scarring.
Zygomaticomalar complex fracture repair usually is performed by a plastic surgeon. In this procedure, mini-plates or micro-plates are inserted through facial incisions to stabilize the bone or bones for healing. Failure to repair a zygomatic injury can result in permanent facial disfiguration such as trismus, which is a flattening of the face; asymmetry of the cheekbones; and a change in the shape and size of the mouth.