Formed by the union of the zygomatic process of the temporal bone and the temporal process of the zygomatic bone, it is from this beam-like structure that the masseter muscle, a major jaw adductor, originates. The zygomatic arch plays a critical role in the mammalian masticatory system. Even though the arch has simple beam-like geometry, we fail to find a simple mechanical explanation for the diversity of arch shape. Furthermore, although modeling the arch as solid cortical bone did not have the effect of elevating strains in other parts of the face, as had been expected, it does have a small effect on stress associated with masseter contraction. One exception is that possessing a blade-like arch leads to elevated strains at the postorbital zygomatic junction and just below the orbits.
We find that the shape of the zygomatic arch has local effects on stain that do not conform to beam theory.
#Front of zygomatic arch series#
Here, we examine the mechanics of the zygomatic arch using a series of finite element modeling experiments in which the cross section of the arch of Pan troglodytes has been modified to conform to idealized shapes (cylindrical, elliptical, blade-like). A stiffer arch may lead to an increase in the relative proportion of applied muscle load being transmitted through the arch to other cranial regions, resulting in elevated cranial stress (and thus, strain). We expect zygomatic arches with different cross sectional shapes to vary in the degree to which they resist local bending and torsion due to the contraction of the masseter muscle. Based on geometry, the arch can be hypothesized to be a sub-structural beam whose ability to resist deformation is related to cross sectional shape. Mammalian zygomatic arch shape is remarkably variable, ranging from nearly cylindrical to blade-like in cross section.
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