Anatomical study of factors contributing to zygomatic complex fracture instability in human cadavers

Background: Stable reduction of fractures of the zygomatic complex is essential to avoid long-term aesthetic, sensory, and ocular consequences. Delayed collapse or relapse after reduction of fractures of the zygomatic complex is attributed to muscle forces, when there has been no additional trauma. A number of studies have identified the masseter muscle as a contributor, but none has described the role of the temporalis muscle. Methods: The origins of the temporalis muscle were examined in six cadaveric dissections. The temporal and zygomatic regions were exposed through a temporoparietal flap. Bone cuts were made above and below the frontozygomatic suture in the lateral orbital margin. The lateral orbital margin was then fractured and reflected laterally on its periosteum so that muscle attachments could be seen clearly. Results: In all six dissections, the authors found that the temporalis muscle took origin not only from the floor of the temporal fossa and temporalis fascia but also from the lateral margin of the orbit and the frontal process of the zygomatic bone as far down as the body of the zygoma. Conclusions: The authors postulate that the functional forces exerted by this muscle on the zygomatic complex cause postoperative distraction at the frontozygomatic suture. The authors' findings provide further anatomical evidence to support internal fixation of all fractures of the zygomatic complex, even those that are considered clinically stable, if permanent flattening of the cheekbone is to be avoided.