Jaw muscles and the skull in mammals: the biomechanics of mastication

Herring, Susan W.; Rafferty, Katherine L.; Liu, Zi Jun; Marshall, Christopher D.

doi:10.1016/s1095-6433(01)00472-x

Cited by 135 publications

(128 citation statements)

References 35 publications

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“…The data for Otolemur come from experiments on one adult O. garnetti, two adult male (Ravosa et al 2000 a) and one adult female O. crassicaudatus (Ross 2001). Data are also available from numerous individuals of min- (Herring and Teng 2000;Herring et al 1996Herring et al , 2001Rafferty et al 2000) and two Alligator mississipiensis (Ross and Metzger, unpublished data).…”

Section: Methodsmentioning

confidence: 99%

“…When peak c-max values were not reported (Dechow and Hylander 2000), the maximum values of e 1 and e 2 re- corded during a single experiment were used to estimate peak c-max. In the case of the data from the pigs, neither c-max nor maximum e 1 and e 2 data were available, so peak c-max data are not presented (Herring and Teng 2000;Herring et al 1996Herring et al , 2001Rafferty et al 2000). The primate and pig mean c-max values were calculated using only working-side mastication data, pooling data from all food types.…”

Section: Methodsmentioning

confidence: 99%

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Bone strain gradients and optimization in vertebrate skulls

Ross

Metzger

2004

Annals of Anatomy - Anatomischer Anzeiger

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Summary. It is often stated that the skull is optimally designed for resisting feeding forces, where optimality is defined as maximum strength with minimum material. Running counter to this hypothesis are bone strain gradients -variation in bone strain magnitudes across the skull -which in the primate skull have been hypothesized to suggest that different parts of the skull are optimized for different functions. In this paper strain gradients in the skulls of four genera of primates, Sus, and Alligator were documented and compared. Strain gradients were pervasive in all taxa sampled. Patterns of strain gradients showed inter-taxon differences, but strains in the mandible and zygomatic arch were always higher than those in the circumorbital and neurocranial regions. Strain magnitudes in Alligator were twice as high as those in mammals. Strain gradients were also positively allometric; i. e., larger primates show steeper gradients (larger differences) between the mandible and circumorbital region than smaller primates. Different strain magnitudes in different areas of the same animal are hypothesized to reflect optimization to different criteria. It is therefore hardly surprising that the skull, in which numerous functional systems are found, exhibits very steep gradients. Inter-specific differences in strain magnitudes at similar sites also suggest inter-specific differences in optimality criteria. The higher strain magnitudes in the Alligator skull suggest that the Alligator skull may be designed to experience extremely high strains less frequently whereas the primate skull may be designed to resist lower strains more frequently.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Bone strain gradients and optimization in vertebrate skulls

Ross

Metzger

2004

Annals of Anatomy - Anatomischer Anzeiger

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“…The former is occlusal force, and its major influence on the skull is to shear the maxilla upward and the mandible downward. 13 The reaction force on the TMJs arises from lever mechanics and the fact that the resultant muscle force rarely if ever passes through the bite point. 14 Depending on the particular species, however, it is clear that there are major differences in the geometry of the muscle resultant and hence the relative magnitude of the TMJ reaction load.…”

Section: Muscles Mastication and The Biomechanics Of The Skullmentioning

confidence: 99%

“…Thus in pigs, mandibular and maxillary strains are identical on the working and balancing sides. 13 In fact, the only part of the pig skull that strains differently depending on the side of chewing is the premaxillary, because incisor occlusion, unlike molar occlusion, is one-sided. 19 Like occlusal force, TMJ loads are reactions to muscle pull.…”

Section: Muscles Mastication and The Biomechanics Of The Skullmentioning

confidence: 99%

Masticatory muscles and the skull: A comparative perspective

Herring

2007

Archives of Oral Biology

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Masticatory muscles are anatomically and functionally complex in all mammals, but relative sizes, orientation of action lines, and fascial subdivisions vary greatly among different species in association with their particular patterns of occlusion and jaw movement. The most common contraction pattern for moving the jaw laterally involves a force couple of protrusor muscles on one side and retrusors on the other. Such asymmetrical muscle usage sets up torques on the skull and combines with occlusal loads to produce bony deformations not only in the tooth-bearing jaw bones, but also in more distant elements such as the braincase. Maintenance of bone in the jaw joint, and probably elsewhere in the skull, is dependent on these loads.

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“…Some texts include equations for shell structures. Although these equations can be used to estimate patterns of stress and strain in relatively simply shaped biological structures, such as long limb bones (Rybicki et al, 1977;Carter et al, 1981;Biewener and Dial, 1995;Demes, 1998;Blob and Biewener, 1999), curved mandibles (Hylander, 1984), or zygomatic arches (Hylander and Johnson, 1997), the complex morphology of the skull makes it difficult to say definitive things about exactly how the skull is deformed during feeding (Herring et al, 2001;Ross, 2001). For example, the question "Is the skull twisting like a cylinder?"…”

Section: Structure-function Relationships Of Complex Shapesmentioning

confidence: 99%

Finite element analysis in vertebrate biomechanics

Ross

2005

Anat. Rec.

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This special issue of The Anatomical Record presents a series of papers that apply the method of finite element analysis (FEA) to questions in vertebrate biomechanics. These papers are salient examples of the use of FEA to test hypotheses regarding structure-function relationships in complexly shaped biological objects such as skulls and in areas of the skeleton that are otherwise impervious to study. FEA is also a powerful tool for studying patterns of stress and strain in fossil animals and artificial constructs hypothesized to represent ancestral conditions. FEA has been used deductively, to study patterns of growth and development, and to investigate whether skull shapes can be created from amorphous blocks using an iterative approach of loading and removing elements. Several of the papers address methodological issues, such as the relative importance of loading conditions and material properties for generating an accurate model and the validation of models using in vivo strain data. Continuing improvements in model building techniques will make possible increased application of FEA to study the functional effects of variation in morphology, whether through ontogenetic or phylogenetic transformations. Key words: finite-element analysis; fossils; dinosaurs; primates; skulls; bone strain; stress Finite-element modeling (FEM) is a numerical tool for solving complex mathematical problems in order to determine patterns of stress, strain, deflections, heat transfer, fluid flow, etc., in computer models of structural components. FEM provides a method for addressing a range of questions that are otherwise intractable, or very difficult to solve , this issue), and is potentially one of the most powerful tools in the methodological arsenal of vertebrate biomechanics.One of the central aims of vertebrate biomechanics is elucidating the functional consequences attendant on the remarkable histological and morphological diversity of vertebrate skeletal tissues (Currey, 2002). This structurefunction relationship is important to clinically oriented research on various disorders or diseases of the skeleton, research aimed at improving skeletal health during longterm space flight, as well as interpretation of skeletons found in the fossil and archeological records. The formfunction relationships of the skeleton are therefore of concern to bioengineers, clinicians, biological anthropologists, and paleontologists, and FEM provides a method for studying them.The availability of increasingly powerful computers at progressively more affordable prices has made FEM an accessible tool for vertebrate biomechanists. Consequently, the wide use of FEM in clinical research is now beginning to be replicated in basic science research. Those of us who are not finite-element modelers can see that FEM clearly presents opportunities, but what is it precisely, and what are its limitations?These questions were addressed in a symposium on finite-element analysis of vertebrate skulls at the International Congress of Vertebrate Morphology in...

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Jaw muscles and the skull in mammals: the biomechanics of mastication

Cited by 135 publications

References 35 publications

Bone strain gradients and optimization in vertebrate skulls

Bone strain gradients and optimization in vertebrate skulls

Masticatory muscles and the skull: A comparative perspective

Finite element analysis in vertebrate biomechanics

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