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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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2
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Wheatley BB, Gilmore EC, Fuller LH, Drake AM, Donahue SW. How the geometry and mechanics of bighorn sheep horns mitigate the effects of impact and reduce the head injury criterion. BIOINSPIRATION & BIOMIMETICS 2023; 18:026005. [PMID: 36652719 DOI: 10.1088/1748-3190/acb478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 01/18/2023] [Indexed: 06/17/2023]
Abstract
Male bighorn sheep (Ovis canadensis) participate in seasonal ramming bouts that can last for hours, yet they do not appear to suffer significant brain injury. Previous work has shown that the keratin-rich horn and boney horncore may play an important role in mitigating brain injury by reducing brain cavity accelerations through energy dissipating elastic mechanisms. However, the extent to which specific horn shapes (such as the tapered spiral of bighorn sheep) may reduce accelerations post-impact remains unclear. Thus, the goals of this work were to (a) quantify bighorn sheep horn shape, particularly the cross-sectional areal properties related to bending that largely dictate post-impact deformations, and (b) investigate the effects of different tapered horn shapes on reducing post-impact accelerations in an impact model with finite element analysis. Cross-sectional areal properties indicate bighorn sheep horns have a medial-lateral bending preference at the horn tip (p= 0.006), which is likely to dissipate energy through medial-lateral horn tip oscillations after impact. Finite element modeling showed bighorn sheep native horn geometry reduced the head injury criterion (HIC15) by 48% compared to horns with cross-sections rotated by 90° to have a cranial-caudal bending preference, and by 125% compared to a circular tapered spiral model. These results suggest that the tapered spiral horn shape of bighorn sheep is advantageous for dissipating energy through elastic mechanisms following an impact. These findings can be used to broadly inform the design of improved safety equipment and impact systems.
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Affiliation(s)
- Benjamin B Wheatley
- Department of Mechanical Engineering, Bucknell University, Lewisburg, PA, United States of America
| | - Emma C Gilmore
- Department of Biomedical Engineering, University of Massachusetts Amherst, Amherst, MA, United States of America
| | - Luca H Fuller
- Department of Biomedical Engineering, University of Massachusetts Amherst, Amherst, MA, United States of America
| | - Aaron M Drake
- Function First Innovative Design, LLC, Denver, CO, United States of America
| | - Seth W Donahue
- Department of Biomedical Engineering, University of Massachusetts Amherst, Amherst, MA, United States of America
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3
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Smith AL, Davis J, Panagiotopoulou O, Taylor AB, Robinson C, Ward CV, Kimbel WH, Alemseged Z, Ross CF. Does the model reflect the system? When two-dimensional biomechanics is not 'good enough'. J R Soc Interface 2023; 20:20220536. [PMID: 36695017 PMCID: PMC9874278 DOI: 10.1098/rsif.2022.0536] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Models are mathematical representations of systems, processes or phenomena. In biomechanics, finite-element modelling (FEM) can be a powerful tool, allowing biologists to test form-function relationships in silico, replacing or extending results of in vivo experimentation. Although modelling simplifications and assumptions are necessary, as a minimum modelling requirement the results of the simplified model must reflect the biomechanics of the modelled system. In cases where the three-dimensional mechanics of a structure are important determinants of its performance, simplified two-dimensional modelling approaches are likely to produce inaccurate results. The vertebrate mandible is one among many three-dimensional anatomical structures routinely modelled using two-dimensional FE analysis. We thus compare the stress regimes of our published three-dimensional model of the chimpanzee mandible with a published two-dimensional model of the chimpanzee mandible and identify several fundamental differences. We then present a series of two-dimensional and three-dimensional FE modelling experiments that demonstrate how three key modelling parameters, (i) dimensionality, (ii) symmetric geometry, and (iii) constraints, affect deformation and strain regimes of the models. Our results confirm that, in the case of the primate mandible (at least), two-dimensional FEM fails to meet this minimum modelling requirement and should not be used to draw functional, ecological or evolutionary conclusions.
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Affiliation(s)
- Amanda L. Smith
- Department of Organismal Biology and Anatomy, University of Chicago, 1027 East 57th St, Chicago, IL 60637, USA,Department of Anatomy, Pacific Northwest University of Health Sciences, Yakima, WA 90981, USA
| | - Julian Davis
- Department of Engineering, University of Southern Indiana, 8600 University Blvd, Evansville, IN 47712, USA
| | - Olga Panagiotopoulou
- Department of Anatomy & Developmental Biology, Monash Biomedicine Discovery Institute, Faculty of Medicine Nursing and Health Sciences, Monash University, Clayton, Melbourne, Victoria 3800, Australia
| | | | - Chris Robinson
- Department of Biological Sciences, Bronx Community College, Bronx, NY 10453, USA,Doctoral Program in Anthropology, The Graduate Center, City University of New York, New York, NY 10016, USA
| | - Carol V. Ward
- Department of Pathology & 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 St, Chicago, IL 60637, USA
| | - Callum F. Ross
- Department of Anatomy, Pacific Northwest University of Health Sciences, Yakima, WA 90981, USA
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4
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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: 6] [Impact Index Per Article: 2.0] [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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Ackermans NL, Varghese M, Wicinski B, Torres J, De Gasperi R, Pryor D, Elder GA, Gama Sosa MA, Reidenberg JS, Williams TM, Hof PR. Unconventional animal models for traumatic brain injury and chronic traumatic encephalopathy. J Neurosci Res 2021; 99:2463-2477. [PMID: 34255876 PMCID: PMC8596618 DOI: 10.1002/jnr.24920] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/09/2021] [Accepted: 06/24/2021] [Indexed: 12/11/2022]
Abstract
Traumatic brain injury (TBI) is one of the main causes of death worldwide. It is a complex injury that influences cellular physiology, causes neuronal cell death, and affects molecular pathways in the brain. This in turn can result in sensory, motor, and behavioral alterations that deeply impact the quality of life. Repetitive mild TBI can progress into chronic traumatic encephalopathy (CTE), a neurodegenerative condition linked to severe behavioral changes. While current animal models of TBI and CTE such as rodents, are useful to explore affected pathways, clinical findings therein have rarely translated into clinical applications, possibly because of the many morphofunctional differences between the model animals and humans. It is therefore important to complement these studies with alternative animal models that may better replicate the individuality of human TBI. Comparative studies in animals with naturally evolved brain protection such as bighorn sheep, woodpeckers, and whales, may provide preventive applications in humans. The advantages of an in-depth study of these unconventional animals are threefold. First, to increase knowledge of the often-understudied species in question; second, to improve common animal models based on the study of their extreme counterparts; and finally, to tap into a source of biological inspiration for comparative studies and translational applications in humans.
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Affiliation(s)
- Nicole L Ackermans
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Merina Varghese
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Bridget Wicinski
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Joshua Torres
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Rita De Gasperi
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- General Medical Research Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
| | - Dylan Pryor
- General Medical Research Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
| | - Gregory A Elder
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Neurology Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
| | - Miguel A Gama Sosa
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- General Medical Research Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
| | - Joy S Reidenberg
- Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Terrie M Williams
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, USA
| | - Patrick R Hof
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Tobiansky DJ, Long KM, Hamden JE, Brawn JD, Fuxjager MJ. Cost-reducing traits for agonistic head collisions: a case for neurophysiology. Integr Comp Biol 2021; 61:1394-1405. [PMID: 33885750 DOI: 10.1093/icb/icab034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many animal species have evolved extreme behaviors requiring them to engage in repeated high-impact collisions. These behaviors include mating displays like headbutting in sheep and drumming in woodpeckers. To our knowledge, these taxa do not experience any notable acute head trauma, even though the deceleration forces would cause traumatic brain injury in most animals. Previous research has focused on skeletomuscular morphology, biomechanics, and material properties in an attempt to explain how animals moderate these high-impact forces. However, many of these behaviors are understudied, and most morphological or computational studies make assumptions about the behavior without accounting for the physiology of an organism. Studying neurophysiological and immune adaptations that co-vary with these behaviors can highlight unique or synergistic solutions to seemingly deleterious behavioral displays. Here, we argue that selection for repeated, high-impact head collisions may rely on a suite of coadaptations in intracranial physiology as a cost-reducing mechanism. We propose that there are three physiological systems that could mitigate the effects of repeated head trauma: (i) the innate neuroimmune response, (ii) the glymphatic system, and (iii) the choroid plexus. These systems are interconnected yet can evolve in an independent manner. We then briefly describe the function of these systems, their role in head trauma, and research that has examined how these systems may evolve to help reduce the cost of repeated, forceful head impacts. Ultimately, we note that little is known about cost-reducing intracranial mechanisms making it a novel field of comparative study that is ripe for exploration.
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Affiliation(s)
| | - Kira M Long
- The University of Illinois at Urbana-Champaign, Urbana-Champaign, IL USAKML
| | | | - Jeffrey D Brawn
- The University of Illinois at Urbana-Champaign, Urbana-Champaign, IL USAJDB
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7
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Rico-Guevara A, Hurme KJ. Intrasexually selected weapons. Biol Rev Camb Philos Soc 2019; 94:60-101. [PMID: 29924496 DOI: 10.1111/brv.12436] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 05/14/2018] [Accepted: 05/18/2018] [Indexed: 01/24/2023]
Abstract
We propose a practical concept that distinguishes the particular kind of weaponry that has evolved to be used in combat between individuals of the same species and sex, which we term intrasexually selected weapons (ISWs). We present a treatise of ISWs in nature, aiming to understand their distinction and evolution from other secondary sex traits, including from 'sexually selected weapons', and from sexually dimorphic and monomorphic weaponry. We focus on the subset of secondary sex traits that are the result of same-sex combat, defined here as ISWs, provide not previously reported evolutionary patterns, and offer hypotheses to answer questions such as: why have only some species evolved weapons to fight for the opposite sex or breeding resources? We examined traits that seem to have evolved as ISWs in the entire animal phylogeny, restricting the classification of ISW to traits that are only present or enlarged in adults of one of the sexes, and are used as weapons during intrasexual fights. Because of the absence of behavioural data and, in many cases, lack of sexually discriminated series from juveniles to adults, we exclude the fossil record from this review. We merge morphological, ontogenetic, and behavioural information, and for the first time thoroughly review the tree of life to identify separate evolution of ISWs. We found that ISWs are only found in bilateral animals, appearing independently in nematodes, various groups of arthropods, and vertebrates. Our review sets a reference point to explore other taxa that we identify with potential ISWs for which behavioural or morphological studies are warranted. We establish that most ISWs come in pairs, are located in or near the head, are endo- or exoskeletal modifications, are overdeveloped structures compared with those found in females, are modified feeding structures and/or locomotor appendages, are most common in terrestrial taxa, are frequently used to guard females, territories, or both, and are also used in signalling displays to deter rivals and/or attract females. We also found that most taxa lack ISWs, that females of only a few species possess better-developed weapons than males, that the cases of independent evolution of ISWs are not evenly distributed across the phylogeny, and that animals possessing the most developed ISWs have non-hunting habits (e.g. herbivores) or are faunivores that prey on very small prey relative to their body size (e.g. insectivores). Bringing together perspectives from studies on a variety of taxa, we conceptualize that there are five ways in which a sexually dimorphic trait, apart from the primary sex traits, can be fixed: sexual selection, fecundity selection, parental role division, differential niche occupation between the sexes, and interference competition. We discuss these trends and the factors involved in the evolution of intrasexually selected weaponry in nature.
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Affiliation(s)
- Alejandro Rico-Guevara
- Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building, Berkeley, CA, 94720, U.S.A.,Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd, Unit 3043, Storrs, CT, 06269, U.S.A.,Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Código Postal 11001, Bogotá DC, Colombia
| | - Kristiina J Hurme
- Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building, Berkeley, CA, 94720, U.S.A.,Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd, Unit 3043, Storrs, CT, 06269, U.S.A
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Churchill M, Geisler JH, Beatty BL, Goswami A. Evolution of cranial telescoping in echolocating whales (Cetacea: Odontoceti). Evolution 2018; 72:1092-1108. [DOI: 10.1111/evo.13480] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/23/2018] [Indexed: 12/01/2022]
Affiliation(s)
- Morgan Churchill
- Department of Biology University of Wisconsin Oshkosh Oshkosh Wisconsin 54901
- Department of Anatomy, College of Osteopathic Medicine New York Institute of Technology Old Westbury New York 11568
| | - Jonathan H. Geisler
- Department of Biology University of Wisconsin Oshkosh Oshkosh Wisconsin 54901
| | - Brian L. Beatty
- Department of Biology University of Wisconsin Oshkosh Oshkosh Wisconsin 54901
| | - Anjali Goswami
- Life Sciences Department The Natural History Museum London SW7 5BD United Kingdom
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9
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Panagiotopoulou O, Iriarte-Diaz J, Wilshin S, Dechow PC, Taylor AB, Mehari Abraha H, Aljunid SF, Ross CF. In vivo bone strain and finite element modeling of a rhesus macaque mandible during mastication. ZOOLOGY 2017; 124:13-29. [PMID: 29037463 DOI: 10.1016/j.zool.2017.08.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 08/25/2017] [Accepted: 08/25/2017] [Indexed: 12/29/2022]
Abstract
Finite element analysis (FEA) is a commonly used tool in musculoskeletal biomechanics and vertebrate paleontology. The accuracy and precision of finite element models (FEMs) are reliant on accurate data on bone geometry, muscle forces, boundary conditions and tissue material properties. Simplified modeling assumptions, due to lack of in vivo experimental data on material properties and muscle activation patterns, may introduce analytical errors in analyses where quantitative accuracy is critical for obtaining rigorous results. A subject-specific FEM of a rhesus macaque mandible was constructed, loaded and validated using in vivo data from the same animal. In developing the model, we assessed the impact on model behavior of variation in (i) material properties of the mandibular trabecular bone tissue and teeth; (ii) constraints at the temporomandibular joint and bite point; and (iii) the timing of the muscle activity used to estimate the external forces acting on the model. The best match between the FEA simulation and the in vivo experimental data resulted from modeling the trabecular tissue with an isotropic and homogeneous Young's modulus and Poisson's value of 10GPa and 0.3, respectively; constraining translations along X,Y, Z axes in the chewing (left) side temporomandibular joint, the premolars and the m1; constraining the balancing (right) side temporomandibular joint in the anterior-posterior and superior-inferior axes, and using the muscle force estimated at time of maximum strain magnitude in the lower lateral gauge. The relative strain magnitudes in this model were similar to those recorded in vivo for all strain locations. More detailed analyses of mandibular strain patterns during the power stroke at different times in the chewing cycle are needed.
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Affiliation(s)
- Olga Panagiotopoulou
- Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia; Department of Anatomy and Developmental Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Melbourne, Victoria 3800, Australia
| | - José Iriarte-Diaz
- Department of Oral Biology, University of Illinois, 801 S. Paulina St., Chicago, IL 60612, USA
| | - Simon Wilshin
- Department of Biomedical Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, United Kingdom
| | - Paul C Dechow
- Department of Biomedical Sciences, College of Dentistry, Texas A&M University, 3302 Gaston Ave., Dallas, TX 75246, USA
| | - Andrea B Taylor
- Department of Basic Science, Touro University, 1310 Club Drive, Mare Island, Vellejo, CA 94592, USA
| | - Hyab Mehari Abraha
- Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Sharifah F Aljunid
- Materialise Unit 5-01, Menara OBYU, No. 4, Jalan PJU 8/8A, Damansara Perdana, 47820 Petaling Jaya, Selangor, Malaysia
| | - Callum F Ross
- Department of Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th St., Chicago, IL 60637, USA.
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Rolvien T, Hahn M, Siebert U, Püschel K, Wilke HJ, Busse B, Amling M, Oheim R. Vertebral bone microarchitecture and osteocyte characteristics of three toothed whale species with varying diving behaviour. Sci Rep 2017; 7:1604. [PMID: 28487524 PMCID: PMC5431672 DOI: 10.1038/s41598-017-01926-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 04/06/2017] [Indexed: 11/09/2022] Open
Abstract
Although vertebral bone microarchitecture has been studied in various tetrapods, limited quantitative data are available on the structural and compositional changes of vertebrae in marine mammals. Whales exhibit exceptional swimming and diving behaviour, and they may not be immune to diving-associated bone pathologies. Lumbar vertebral bodies were analysed in three toothed whale species: the sperm whale (Physeter macrocephalus), orca (Orcinus orca) and harbour porpoise (Phocoena phocoena). The bone volume fraction (BV/TV) did not scale with body size, although the trabeculae were thicker, fewer in number and further apart in larger whale species than in the other two species. These parameters had a negative allometric scaling relationship with body length. In sperm whales and orcas, the analyses revealed a central ossification zone (“bone-within-bone”) with an increased BV/TV and trabecular thickness. Furthermore, a large number of empty osteocyte lacunae was observed in the sperm whales. Quantitative backscattered electron imaging showed that the lacunae were significantly smaller and less densely packed. Our results indicate that whales have a unique vertebral bone morphology with an inside-out appearance and that deep diving may result in a small number of viable osteocytes because of diving depth-related osteocyte death.
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Affiliation(s)
- Tim Rolvien
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - Michael Hahn
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstrasse 6, 25761, Buesum, Germany
| | - Klaus Püschel
- Department of Forensic Medicine, University Medical Center Hamburg-Eppendorf, Butenfeld 34, 22529, Hamburg, Germany
| | - Hans-Joachim Wilke
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14 D, 89081, Ulm, Germany
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany.
| | - Ralf Oheim
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
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Panagiotopoulou O, Spyridis P, Mehari Abraha H, Carrier DR, Pataky TC. Architecture of the sperm whale forehead facilitates ramming combat. PeerJ 2016; 4:e1895. [PMID: 27069822 PMCID: PMC4824896 DOI: 10.7717/peerj.1895] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/14/2016] [Indexed: 11/20/2022] Open
Abstract
Herman Melville’s novel Moby Dick was inspired by historical instances in which large sperm whales (Physeter macrocephalus L.) sank 19th century whaling ships by ramming them with their foreheads. The immense forehead of sperm whales is possibly the largest, and one of the strangest, anatomical structures in the animal kingdom. It contains two large oil-filled compartments, known as the “spermaceti organ” and “junk,” that constitute up to one-quarter of body mass and extend one-third of the total length of the whale. Recognized as playing an important role in echolocation, previous studies have also attributed the complex structural configuration of the spermaceti organ and junk to acoustic sexual selection, acoustic prey debilitation, buoyancy control, and aggressive ramming. Of these additional suggested functions, ramming remains the most controversial, and the potential mechanical roles of the structural components of the spermaceti organ and junk in ramming remain untested. Here we explore the aggressive ramming hypothesis using a novel combination of structural engineering principles and probabilistic simulation to determine if the unique structure of the junk significantly reduces stress in the skull during quasi-static impact. Our analyses indicate that the connective tissue partitions in the junk reduce von Mises stresses across the skull and that the load-redistribution functionality of the former is insensitive to moderate variation in tissue material parameters, the thickness of the partitions, and variations in the location and angle of the applied load. Absence of the connective tissue partitions increases skull stresses, particularly in the rostral aspect of the upper jaw, further hinting of the important role the architecture of the junk may play in ramming events. Our study also found that impact loads on the spermaceti organ generate lower skull stresses than an impact on the junk. Nevertheless, whilst an impact on the spermaceti organ would reduce skull stresses, it would also cause high compressive stresses on the anterior aspect of the organ and the connective tissue case, possibly making these structures more prone to failure. This outcome, coupled with the facts that the spermaceti organ houses sensitive and essential sonar producing structures and the rostral portion of junk, rather than the spermaceti organ, is frequently a site of significant scarring in mature males suggest that whales avoid impact with the spermaceti organ. Although the unique structure of the junk certainly serves multiple functions, our results are consistent with the hypothesis that the structure also evolved to function as a massive battering ram during male-male competition.
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Affiliation(s)
- Olga Panagiotopoulou
- Faculty of Medicine and Biomedical Sciences, Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland , Brisbane , Australia
| | - Panagiotis Spyridis
- Polytropos Ltd, London, United Kingdom; Department of Civil Engineering and Natural Hazards, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Hyab Mehari Abraha
- Faculty of Medicine and Biomedical Sciences, Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland , Brisbane , Australia
| | - David R Carrier
- Department of Biology, University of Utah , Salt Lake City , Utah, United States of America
| | - Todd C Pataky
- Institute for Fiber Engineering, Department of Bioengineering, Shinshu University , Ueda, Nagano , Japan
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