Human Masticatory Muscle Volume and Zygomatico-mandibular Form in Adults with Mandibular Prognathism

Abstract

Although several investigators have reported associations between masticatory muscles and skeletal craniofacial form, there is no agreement on the association. We tested the hypothesis that masticatory muscle volume correlates with the size and form of the adjacent local skeletal sites. For this purpose, we investigated the morphological association of the cross-sectional area and volume of temporal and masseter muscles with zygomatico-mandibular skeletal structures using computerized tomography (CT) in 25 male adults with mandibular prognathism. Muscle variables significantly correlated with widths of the bizygomatic arch and temporal fossa but not with the cranium width. Masseter volume significantly correlated with cross-sectional areas of the zygomatic arch and mandibular ramus. Masseter orientation was almost perpendicular to the zygomatic arch and mandibular antegonial region. The zygomatic arch angle significantly correlated with the antegonial angle. The results of the study suggest that the masticatory muscles exert influence on the adjacent local skeletal sites.

Mandibular morphology in two archaeological human skeletal samples from northwest Europe with different masticatory regimes

“…Of the mandibular dimensions of interest to orthodontists that have direct analogues in the measurements commonly taken in osteometric work, the most widely studied are the mandibular angle (the angle formed by the posterior border of the ramus and the base of the corpus), and measures of ramus height and corpus length. Low mandibular angle has been associated with increased bite force (Ingervall and Helkimo, 1978;Kiliaridis et al, 1995;Raadsheer et al, 1999;Ringqvist, 1973;Sondang et al, 2003;Throckmorton et al, 2000), and greater development of masticatory musculature (Bennington et al, 1999;Bloem and van Hoof, 1971;Gelbke, 1958;Gionhaku and Lowe, 1989;Kasai et al, 1994Kasai et al, , 1997, although some studies have failed to identify such relationships (Charalampidou et al, 2008;Hannam and Wood, 1989;Ingervall and Thilander, 1974;Kitai et al, 2002;Kubota et al, 1998;van Spronson et al, 1991;Watanabe and Watanabe, 2001;Weijs and Hillen, 1986). Gionhaku and Lowe (1989), Kasai et al (1994), Kubota et al (1998) and Bennington et al (1999) associated greater height of the mandibular ramus with increased masticatory muscular development, but Hannam and Wood (1989) and van Spronson et al (1991) failed to detect an association.…”

Possible causes and significance of cranial robusticity among Pleistocene–Early Holocene Australians

“…Data from Beals et al, 1984;Lahr and Wright, 1996;Brown, 1998;Stringer, 1998a forcible elevation (Vitti and Basmajian, 1977), and probably also retraction, of the mandible during mastication. Moreover, zygomatic arch and temporal fossa width are also correlated with the volume of the masseter and temporal muscles (Kitai et al, 2002). Thus, it seems likely that the marked postorbital constriction and likely broad upper face of WLH50 (as indicated by its broad horizontal breadth across the supraorbital torus) and other 'robust' Australian crania are associated with large volume and greater exertion force of the muscles of mastication.…”

“…Thus, it seems likely that the marked postorbital constriction and likely broad upper face of WLH50 (as indicated by its broad horizontal breadth across the supraorbital torus) and other 'robust' Australian crania are associated with large volume and greater exertion force of the muscles of mastication. It is noteworthy that the volume of these muscles is not associated with cranial width (Kitai et al, 2002). Although inheritance has an important influence on facial features (Proffit, 1993), skeletal morphology is modified during life by mechanical stresses placed upon it.…”

“…Posteriorly, the ectocranial table associated with the temporal lines swells to form an angular torus. It is now well understood that large muscle volume and the effects of mechanical stress from mastication largely determine the size of adjacent local skeletal sites which accommodate muscles and on which muscle force is exerted (Kitai et al, 2002). Thus, the development of strong temporal crests on the frontal and an angular torus on the posterior parietal is likely to be associated with mechanical stress during Values in parentheses are standard deviations followed by sample size.…”

“…The position and degree of postorbital constriction in the cranium are also a direct consequence of the amount of separation between the orbit and neurocranial wall in addition to the size of the muscles of mastication within the temporal fossa (Moss and Young, 1960;Shea, 1985;Kitai et al, 2002). Thus, the presence of marked postorbital constriction in WLH50 and other 'robust' Australian specimens is directly related to: (1) the high degree of separation between the braincase and orbit produced by anterior growth of the superior orbital plate (i.e.…”