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Wilken AT, Schultz JA, Luo ZX, Ross CF. A new biomechanical model of the mammal jaw based on load path analysis. J Exp Biol 2024; 227:jeb247030. [PMID: 39092673 PMCID: PMC11463961 DOI: 10.1242/jeb.247030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 07/24/2024] [Indexed: 08/04/2024]
Abstract
The primary function of the tetrapod jaw is to transmit jaw muscle forces to bite points. The routes of force transfer in the jaw have never been studied but can be quantified using load paths - the shortest, stiffest routes from regions of force application to support constraints. Here, we use load path analysis to map force transfer from muscle attachments to bite point and jaw joint, and to evaluate how different configurations of trabecular and cortical bone affect load paths. We created three models of the mandible of the Virginia opossum, Didelphis virginiana, each with a cortical bone shell, but with different material properties for the internal spaces: (1) a cortical-trabecular model, in which the interior space is modeled with bulk properties of trabecular bone; (2) a cortical-hollow model, in which trabeculae and mandibular canal are modeled as hollow; and (3) a solid-cortical model, in which the interior is modeled as cortical bone. The models were compared with published in vivo bite force and bone strain data, and the load paths calculated for each model. The trabecular model, which is preferred because it most closely approximates the actual morphology, was best validated by in vivo data. In all three models, the load path was confined to cortical bone, although its route within the cortex varied depending on the material properties of the inner model. Our analysis shows that most of the force is transferred through the cortical, rather than trabecular bone, and highlights the potential of load path analysis for understanding form-function relationships in the skeleton.
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Affiliation(s)
- Alec T. Wilken
- The University of Chicago, Department of Organismal Biology and Anatomy, 1027 E 57th Street, Chicago, IL, 60637, USA
| | - Julia A. Schultz
- Rheinische Friedrich-Wilhelms-Universität Bonn, Section Paleontology, Institute of Geosciences, 53115 Bonn, Germany
| | - Zhe-Xi Luo
- The University of Chicago, Department of Organismal Biology and Anatomy, 1027 E 57th Street, Chicago, IL, 60637, USA
| | - Callum F. Ross
- The University of Chicago, Department of Organismal Biology and Anatomy, 1027 E 57th Street, Chicago, IL, 60637, USA
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Panagiotopoulou O, Robinson D, Iriarte-Diaz J, Ackland D, Taylor AB, Ross CF. Dynamic finite element modelling of the macaque mandible during a complete mastication gape cycle. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220549. [PMID: 37839457 PMCID: PMC10577025 DOI: 10.1098/rstb.2022.0549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 09/14/2023] [Indexed: 10/17/2023] Open
Abstract
Three-dimensional finite element models (FEMs) are powerful tools for studying the mechanical behaviour of the feeding system. Using validated, static FEMs we have previously shown that in rhesus macaques the largest food-related differences in strain magnitudes during unilateral postcanine chewing extend from the lingual symphysis to the endocondylar ridge of the balancing-side ramus. However, static FEMs only model a single time point during the gape cycle and probably do not fully capture the mechanical behaviour of the jaw during mastication. Bone strain patterns and moments applied to the mandible are known to vary during the gape cycle owing to variation in the activation peaks of the jaw-elevator muscles, suggesting that dynamic models are superior to static ones in studying feeding biomechanics. To test this hypothesis, we built dynamic FEMs of a complete gape cycle using muscle force data from in vivo experiments to elucidate the impact of relative timing of muscle force on mandible biomechanics. Results show that loading and strain regimes vary across the chewing cycle in subtly different ways for different foods, something which was not apparent in static FEMs. These results indicate that dynamic three-dimensional FEMs are more informative than static three-dimensional FEMs in capturing the mechanical behaviour of the jaw during feeding by reflecting the asymmetry in jaw-adductor muscle activations during a gape cycle. This article is part of the theme issue 'Food processing and nutritional assimilation in animals'.
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Affiliation(s)
- Olga Panagiotopoulou
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria 3800, Australia
| | - Dale Robinson
- Department of Biomedical Engineering, University of Melbourne, Melbourne, Victoria 3053, Australia
| | - Jose Iriarte-Diaz
- Department of Biology, University of the South, Sewanee, TN 37383, USA
| | - David Ackland
- Department of Biomedical Engineering, University of Melbourne, Melbourne, Victoria 3053, Australia
| | - Andrea B. Taylor
- Department of Foundational Biomedical Sciences, Touro University California, Vallejo, CA 94592, USA
| | - Callum F. Ross
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
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Laird MF, Iriarte-Diaz J, Byron CD, Granatosky MC, Taylor AB, Ross CF. Gape drives regional variation in temporalis architectural dynamics in tufted capuchins. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220550. [PMID: 37839440 PMCID: PMC10577035 DOI: 10.1098/rstb.2022.0550] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 06/10/2023] [Indexed: 10/17/2023] Open
Abstract
Dynamic changes in jaw movements and bite forces depend on muscle architectural and neural factors that have rarely been compared within the same muscle. Here we investigate how regional muscle architecture dynamics-fascicle rotation, shortening, lengthening and architectural gear ratio (AGR)-vary during chewing across a functionally heterogeneous muscle. We evaluate whether timing in architecture dynamics relates to gape, food material properties and/or muscle activation. We also examine whether static estimates of temporalis fibre architecture track variation in dynamic architecture. Fascicle-level architecture dynamics were measured in three regions of the superficial temporalis of three adult tufted capuchins (Sapajus apella) using biplanar videoradiography and the XROMM workflow. Architecture dynamics data were paired with regional fine-wire electromyography data from four adult tufted capuchins. Gape accounted for most architectural change across the temporalis, but architectural dynamics varied between regions. Mechanically challenging foods were associated with lower AGRs in the anterior region. The timing of most dynamic architectural changes did not vary between regions and differed from regional variation in static architecture. Collectively these findings suggest that, when modelling temporalis muscle force production in extant and fossil primates, it is important to account for the effects of gape, regionalization and food material properties. This article is part of the theme issue 'Food processing and nutritional assimilation in animals'.
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Affiliation(s)
- Myra F. Laird
- Department of Basic and Translational Sciences, University of Pennsylvania, Levy 443, 4010 Locust Street, Philadelphia, PA 19104, USA
| | - Jose Iriarte-Diaz
- Department of Biology, University of the South, Sewanee, TN 37383-1000, USA
| | - Craig D. Byron
- Department of Biology, Mercer University, Macon, GA 312014, USA
| | - Michael C. Granatosky
- Department of Anatomy, New York Institute of Technology, Old Westbury, NY 11545, USA
| | - Andrea B. Taylor
- Department of Foundational Biomedical Sciences, Touro University, Vallejo, CA 94592, USA
| | - Callum F. Ross
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
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VAN Linden L, Stoops K, Dumbá LCCS, Cozzuol MA, Maclaren JA. Sagittal crest morphology decoupled from relative bite performance in Pleistocene tapirs (Perissodactyla: Tapiridae). Integr Zool 2023; 18:254-277. [PMID: 35048523 DOI: 10.1111/1749-4877.12627] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bite force is often associated with specific morphological features, such as sagittal crests. The presence of a pronounced sagittal crest in some tapirs (Perissodactyla: Tapiridae) was recently shown to be negatively correlated with hard-object feeding, in contrast with similar cranial structures in carnivorans. The aim of this study was to investigate bite forces and sagittal crest heights across a wide range of modern and extinct tapirs and apply a comparative investigation to establish whether these features are correlated across a broad phylogenetic scope. We examined a sample of 71 specimens representing 15 tapir species (5 extant, 10 extinct) using the dry-skull method, linear measurements of cranial features, phylogenetic reconstruction, and comparative analyses. Tapirs were found to exhibit variation in bite force and sagittal crest height across their phylogeny and between different biogeographical realms, with high-crested morphologies occurring mostly in Neotropical species. The highest bite forces within tapirs appear to be driven by estimates for the masseter-pterygoid muscle complex, rather than predicted forces for the temporalis muscle. Our results demonstrate that relative sagittal crest height is poorly correlated with relative cranial bite force, suggesting high force application is not a driver for pronounced sagittal crests in this sample. The divergent biomechanical capabilities of different contemporaneous tapirids may have allowed multiple species to occupy overlapping territories and partition resources to avoid excess competition. Bite forces in tapirs peak in Pleistocene species, independent of body size, suggesting possible dietary shifts as a potential result of climatic changes during this epoch.
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Affiliation(s)
- Lisa VAN Linden
- Functional Morphology Lab, Department of Biology, Campus Drie Eiken, Universiteit Antwerpen, Antwerpen, Belgium
| | - Kim Stoops
- Functional Morphology Lab, Department of Biology, Campus Drie Eiken, Universiteit Antwerpen, Antwerpen, Belgium
| | - Larissa C C S Dumbá
- Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil
| | - Mario A Cozzuol
- Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil
| | - Jamie A Maclaren
- Functional Morphology Lab, Department of Biology, Campus Drie Eiken, Universiteit Antwerpen, Antwerpen, Belgium.,Evolution and Diversity Dynamics Lab, Department of Geology, Université de Liège, Quartier Agora, Liège, Belgium
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Smith AL, Robinson C, Taylor AB, Panagiotopoulou O, Davis J, Ward CV, Kimbel WH, Alemseged Z, Ross CF. Comparative biomechanics of the Pan and Macaca mandibles during mastication: finite element modelling of loading, deformation and strain regimes. Interface Focus 2021; 11:20210031. [PMID: 34938438 PMCID: PMC8361577 DOI: 10.1098/rsfs.2021.0031] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/09/2021] [Indexed: 10/17/2023] Open
Abstract
The mechanical behaviour of the mandibles of Pan and Macaca during mastication was compared using finite element modelling. Muscle forces were calculated using species-specific measures of physiological cross-sectional area and scaled using electromyographic estimates of muscle recruitment in Macaca. Loading regimes were compared using moments acting on the mandible and strain regimes were qualitatively compared using maps of principal, shear and axial strains. The enlarged and more vertically oriented temporalis and superficial masseter muscles of Pan result in larger sagittal and transverse bending moments on both working and balancing sides, and larger anteroposterior twisting moments on the working side. The mandible of Pan experiences higher principal strain magnitudes in the ramus and mandibular prominence, higher transverse shear strains in the top of the symphyseal region and working-side corpus, and a predominance of sagittal bending-related strains in the balancing-side mandible. This study lays the foundation for a broader comparative study of Hominidae mandibular mechanics in extant and fossil hominids using finite element modelling. Pan's larger and more vertical masseter and temporalis may make it a more suitable model for hominid mandibular biomechanics than Macaca.
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Affiliation(s)
- Amanda L. Smith
- Department of Anatomy, Pacific Northwest University of Health Sciences, 200 University Parkway, Yakima, WA 98901, USA
- Department of Organismal Biology and Anatomy, University of Chicago, 1027 East 57th Street, Chicago, IL 60637, USA
| | - Chris Robinson
- Department of Biological Sciences, Bronx Community College, Bronx, NY 10453, USA
| | | | - Olga Panagiotopoulou
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Melbourne, Victoria 3800, Australia
| | - Julian Davis
- Department of Engineering, University of Southern Indiana, 8600 University Boulevard, Evansville, IN 47712, USA
| | - Carol V. Ward
- Department of Pathology and Anatomical Sciences, One Hospital Drive, University of Missouri, Columbia, MO 65212, USA
| | - William H. Kimbel
- School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85287-4101, USA
| | - Zeresenay Alemseged
- Department of Organismal Biology and Anatomy, University of Chicago, 1027 East 57th Street, Chicago, IL 60637, USA
| | - Callum F. Ross
- Department of Organismal Biology and Anatomy, University of Chicago, 1027 East 57th Street, Chicago, IL 60637, USA
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Kramer PA, Berthaume MA. Introduction to the theme issue ‘Biological anthroengineering’. Interface Focus 2021. [DOI: 10.1098/rsfs.2021.0058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Patricia Ann Kramer
- Department of Anthropology, University of Washington, Seattle, WA 98195-3100, USA
- Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA 98195-3100, USA
| | - Michael A. Berthaume
- Division of Mechanical Engineering and Design, London South Bank University, London, UK
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