Predicting Skull Loading: Applying Multibody Dynamics Analysis to a Macaque Skull

Abstract

Evaluating stress and strain fields in anatomical structures is a way to test hypotheses that relate specific features of facial and skeletal morphology to mechanical loading. Engineering techniques such as finite element analysis are now commonly used to calculate stress and strain fields, but if we are to fully accept these methods we must be confident that the applied loading regimens are reasonable. Multibody dynamics analysis (MDA) is a relatively new three dimensional computer modeling technique that can be used to apply varying muscle forces to predict joint and bite forces during static and dynamic motions. The method ensures that equilibrium of the structure is maintained at all times, even for complex statically indeterminate problems, eliminating nonphysiological constraint conditions often seen with other approaches. This study describes the novel use of MDA to investigate the influence of different muscle representations on a macaque skull model (Macaca fascicularis), where muscle groups were represented by either a single, multiple, or wrapped muscle fibers. The impact of varying muscle representation on stress fields was assessed through additional finite element simulations. The MDA models highlighted that muscle forces varied with gape and that forces within individual muscle groups also varied; for example, the anterior strands of the superficial masseter were loaded to a greater extent than the posterior strands. The direction of the muscle force was altered when temporalis muscle wrapping was modeled, and was coupled with compressive contact forces applied to the frontal, parietal and temporal bones of the cranium during biting.

Modularity and integration in ontogeny of the middle facial skeleton in two West African monkey species: collared mangabey (Cercocebus torquatus) and olive colobus (Procolobus verus)

“…It might be an adaptation for accommodation of large incisors (a characteristic trait of all mangabeys) and a way to increase of the whole bone robustness before beginning of the extreme masticatory loadings which start in this animals during the first year of life (McGraw, 2011). So in this case masticatory adaptation might express itself not as a result of direct stimulation of bone growth by cyclic strains (Kopher & Mao, 2003;Curtis et al, 2008;Herring, 2008) but prior to this stimulation as a preparation for it. The masticatory muscles do not influence growth during prenatal and early postnatal periods but the nasal septum is very active at that time as a source of quasi-static stress to adjacent bones (Latham, 1970;Mooney & Siegel, 1986).…”

“…2) Points belonging to both the malar bone and the zygomatic arch, a core of conventional masticatory module (Cheverud, 1982;Richmond et al, 2005;Curtis et al, 2008), were also excluded. We have excluded points from the alveolar process as well since this structure is known to be particularly strongly influenced epigenetically (Enlow, 1975).…”

Biomechanical assessment of evolutionary changes in the lepidosaurian skull

“…The application of 2 powerful computational toolsmultibody dynamic analysis (MDA) and finite element analysis (FEA)-is becoming widespread in the field of functional morphology to answer questions surrounding the biomechanical significance of cranial design (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33). We implemented both of these techniques on Uromastyx hardwickii, a streptostylic but otherwise akinetic herbivorous lizard.…”

A Sensitivity Analysis to the Role of the Fronto‐Parietal Suture in Lacerta Bilineata: A Preliminary Finite Element Study

“…Therefore, varying the properties of the sutures had more of an impact on the anterior regions than the posterior regions (considering the movement across the FP suture). This observation highlights the importance of applying physiological loading conditions to the skull where muscle forces and joint forces would be expected (Duda et al, 1998;Curtis et al, 2008Curtis et al, , 2010Moazen et al, 2008a,b).…”

“…It is important to impose accurate boundary conditions in FE analysis to obtain results that correspond to the complex biological condition (Curtis et al, 2008;Moazen et al, 2008a). However, as far as the objective of this sensitivity study is concerned, a simplified boundary condition was imposed on the skull.…”