1
40
9
-
Text
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URL Address
<a href="http://doi.org/10.1002/ajpa.20290" target="_blank" rel="noreferrer noopener">http://doi.org/10.1002/ajpa.20290</a>
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Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Pages
215-224
Issue
2
Volume
129
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Title
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Phase II jaw movements and masseter muscle activity during chewing in Papio anubis
Publisher
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American Journal of Physical Anthropology
Date
A point or period of time associated with an event in the lifecycle of the resource
2006
2006-02
Subject
The topic of the resource
adaptations; Anthropology; bone strain; dentition; emg; evolution; Evolutionary Biology; jaw muscles; loading patterns; macaca-fascicularis; macaques; mastication; power stroke; primates; teeth
Creator
An entity primarily responsible for making the resource
Wall C E; Vinyard C J; Johnson K R; Williams S H; Hylander W L
Description
An account of the resource
It was proposed that the power stroke in primates has two distinct periods of occlusal contact, each with a characteristic motion of the mandibular molars relative to the maxillary molars. The two movements are called phase I and phase IT, and they occur sequentially in that order (Kay and Hiiemae [1974] Am J. Phys. Anthropol. 40:227-256, Kay and Hiiemae [1974] Prosimian Biology, Pittsburgh: University of Pittsburgh Press, p. 501-530). Phase I movement is said to be associated with shearing along a series of crests, producing planar phase I facets and crushing on surfaces on the basins of the molars. Phase I terminates in centric occlusion. Phase II movement is said to be associated with grinding along the same surfaces that were used for crushing at the termination of phase I. Hylander et al. ([1987] Am J. Phys. Anthropol. 72:287-312; see also Hiiemae [1984] Food Acquisition and Processing, London: Academic Press, p. 257-281; Hylander and Crompton [1980] Am J. Phys. Anthropol. 52:239-251, [1986] Arch. Oral. Biol. 31:841-848) analyzed data on macaques and suggested that phase IT movement may not be nearly as significant for food breakdown as phase I movement simply because, based on the magnitude of mandibular bone strain patterns, adductor muscle and occlusal forces are likely negligible during movement out of centric occlusion. Our goal is to better understand the functional significance of phase IT movement within the broader context of masticatory kinematics during the power stroke. We analyze vertical and transverse mandibular motion and relative activity of the masseter and temporalis muscles during phase I and II movements in Papio anubis. We test whether significant muscle activity and, by inference, occlusal force occurs during phase IT movement. We find that during phase IT movement, there is negligible force developed in the superficial and deep masseter and the anterior and posterior temporalis muscles. Furthermore, mandibular movements are small during phase II compared to phase I. These results suggest that grinding during phase IT movement is of minimal importance for food breakdown, and that most food breakdown on phase IT facets occurs primarily at the end of phase I movement (i.e., crushing during phase I movement). We note, however, that depending on the orientation of phase I facets, significant grinding also occurs along phase I facets during phase I. (c) 2005 Wiley-Liss, Inc.
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<a href="http://doi.org/10.1002/ajpa.20290" target="_blank" rel="noreferrer noopener">10.1002/ajpa.20290</a>
Format
The file format, physical medium, or dimensions of the resource
Journal Article
2006
adaptations
American journal of physical anthropology
Anthropology
bone strain
Dentition
emg
Evolution
Evolutionary Biology
Hylander W L
jaw muscles
Johnson K R
Journal Article
loading patterns
macaca-fascicularis
macaques
Mastication
power stroke
Primates
Teeth
Vinyard C J
Wall C E
Williams S H
-
Text
A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text.
URL Address
<a href="http://doi.org/10.1111/j.1469-7580.2008.01008.x" target="_blank" rel="noreferrer noopener">http://doi.org/10.1111/j.1469-7580.2008.01008.x</a>
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Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Pages
65-78
Issue
1
Volume
214
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Title
A name given to the resource
Mandibular corpus bone strain in goats and alpacas: Implications for understanding the biomechanics of mandibular form in selenodont artiodactyls
Publisher
An entity responsible for making the resource available
Journal of Anatomy
Date
A point or period of time associated with an event in the lifecycle of the resource
2009
2009-01
Subject
The topic of the resource
adductor muscle force; Anatomy & Morphology; bone strain; functional-significance; jaw; macaca-fascicularis; mandibles; mandibular corpus; mastication; masticatory biomechanics; morphology; movements; stress; symphyseal fusion
Creator
An entity primarily responsible for making the resource
Williams S H; Vinyard C J; Wall C E; Hylander W L
Description
An account of the resource
The goal of this study is to clarify the functional and biomechanical relationship between jaw morphology and in vivo masticatory loading in selenodont artiodactyls. We compare in vivo strains from the mandibular corpus of goats and alpacas to predicted strain patterns derived from biomechanical models for mandibular corpus loading during mastication. Peak shear strains in both species average 600-700 mu epsilon on the working side and approximately 450 mu epsilon on the balancing side. Maximum principal tension in goats and alpacas is directed at approximately 30 degrees dorsocaudally relative to the long axis of the corpus on the working side and approximately perpendicular to the long axis on the balancing side. Strain patterns in both species indicate primarily torsion of the working-side corpus about the long axis and parasagittal bending and/or lateral transverse bending of the balancing-side corpus. Interpretation of the strain patterns is consistent with comparative biomechanical analyses of jaw morphology suggesting that in goats, the balancing-side mandibular corpus is parasagittally bent whereas in alpacas it experiences lateral transverse bending. However, in light of higher working-side corpus strains, biomechanical explanations of mandibular form also need to consider that torsion influences relative corpus size and shape. Furthermore, the complex combination of loads that occur along the selenodont artiodactyl mandibular corpus during the power stroke has two implications. First, added clarification of these loading patterns requires in vivo approaches for elucidating biomechanical links between mandibular corpus morphology and masticatory loading. Second, morphometric approaches may be limited in their ability to accurately infer masticatory loading regimes of selenodont artiodactyl jaws.
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<a href="http://doi.org/10.1111/j.1469-7580.2008.01008.x" target="_blank" rel="noreferrer noopener">10.1111/j.1469-7580.2008.01008.x</a>
Format
The file format, physical medium, or dimensions of the resource
Journal Article
2009
adductor muscle force
Anatomy & Morphology
bone strain
functional-significance
Hylander W L
jaw
Journal Article
Journal of anatomy
macaca-fascicularis
mandibles
mandibular corpus
Mastication
masticatory biomechanics
morphology
movements
Stress
symphyseal fusion
Vinyard C J
Wall C E
Williams S H
-
Text
A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text.
URL Address
<a href="http://doi.org/10.1002/jez.a.362" target="_blank" rel="noreferrer noopener">http://doi.org/10.1002/jez.a.362</a>
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Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Pages
226-240
Issue
4
Volume
307A
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Title
A name given to the resource
Masticatory motor patterns in ungulates: A quantitative assessment of jaw-muscle coordination in goats, alpacas and horses
Publisher
An entity responsible for making the resource available
Journal of Experimental Zoology Part a-Ecological Genetics and Physiology
Date
A point or period of time associated with an event in the lifecycle of the resource
2007
2007-04
Subject
The topic of the resource
electromyography; emg; force; fusion; mandibular symphysis; masseter muscle; movements; pigs; Zoology
Creator
An entity primarily responsible for making the resource
Williams S H; Vinyard C J; Wall C E; Hylander W L
Description
An account of the resource
We investigated patterns of jaw-muscle coordination during rhythmic mastication in three species of ungulates displaying the marked transverse jaw movements typical of many large mammalian herbivores. In order to quantify consistent motor patterns during chewing, electromyograms were recorded from the superficial masseter, deep masseter, posterior temporalis and medial pterygoid muscles of goats, alpacas and horses. Timing differences between muscle pairs were evaluated in the context of an evolutionary model of jaw-muscle function. In this model, the closing and food reduction phases of mastication are primarily controlled by two distinct muscle groups, triplet I (balancing-side superficial masseter and medial pterygoid and working-side posterior temporalis) and triplet II (working-side superficial masseter and medial pterygoid and balancing-side posterior temporalis), and the asynchronous activity of the working- and balancing-side deep masseters. The three species differ in the extent to which the jaw muscles are coordinated as triplet I and triplet II. Alpacas, And to a lesser extent, goats, exhibit the triplet pattern whereas horses do not. In contrast, all three species show marked asynchrony of the working-side and balancing-side deep masseters, with jaw closing initiated by the working-side muscle and the balancing-side muscle firing much later during closing. However, goats differ from alpacas and horses in the timing of the balancing-side deep masseter relative to the triplet II muscles. This study highlights interspecific differences in the coordination of jaw muscles to influence transverse jaw movements and the production of bite force in herbivorous ungulates.
Identifier
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<a href="http://doi.org/10.1002/jez.a.362" target="_blank" rel="noreferrer noopener">10.1002/jez.a.362</a>
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The file format, physical medium, or dimensions of the resource
Journal Article
2007
Electromyography
emg
force
fusion
Hylander W L
Journal Article
Journal of Experimental Zoology Part a-Ecological Genetics and Physiology
mandibular symphysis
masseter muscle
movements
pigs
Vinyard C J
Wall C E
Williams S H
Zoology
-
Text
A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text.
URL Address
<a href="http://doi.org/10.1093/icb/icr068" target="_blank" rel="noreferrer noopener">http://doi.org/10.1093/icb/icr068</a>
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Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Pages
247-259
Issue
2
Volume
51
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Title
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A Preliminary Analysis of Correlated Evolution in Mammalian Chewing Motor Patterns
Publisher
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Integrative and Comparative Biology
Date
A point or period of time associated with an event in the lifecycle of the resource
2011
2011-08
Subject
The topic of the resource
alpacas; discrete characters; electromyography; emg; fusion; jaw movements; masseter; masticatory muscles; mechanics; morphology; symphyseal; Zoology
Creator
An entity primarily responsible for making the resource
Williams S H; Vinyard C J; Wall C E; Doherty A H; Crompton A W; Hylander W L
Description
An account of the resource
Descriptive and quantitative analyses of electromyograms (EMG) from the jaw adductors during feeding in mammals have demonstrated both similarities and differences among species in chewing motor patterns. These observations have led to a number of hypotheses of the evolution of motor patterns, the most comprehensive of which was proposed by Weijs in 1994. Since then, new data have been collected and additional hypotheses for the evolution of motor patterns have been proposed. Here, we take advantage of these new data and a well-resolved species-level phylogeny for mammals to test for the correlated evolution of specific components of mammalian chewing motor patterns. We focus on the evolution of the coordination of working-side (WS) and balancing-side (BS) jaw adductors (i.e., Weijs' Triplets I and II), the evolution of WS and BS muscle recruitment levels, and the evolution of asynchrony between pairs of muscles. We converted existing chewing EMG data into binary traits to incorporate as much data as possible and facilitate robust phylogenetic analyses. We then tested hypotheses of correlated evolution of these traits across our phylogeny using a maximum likelihood method and the Bayesian Markov Chain Monte Carlo method. Both sets of analyses yielded similar results highlighting the evolutionary changes that have occurred across mammals in chewing motor patterns. We find support for the correlated evolution of (1) Triplets I and II, (2) BS deep masseter asynchrony and Triplets I and II, (3) a relative delay in the activity of the BS deep masseter and a decrease in the ratio of WS to BS muscle recruitment levels, and (4) a relative delay in the activity of the BS deep masseter and a delay in the activity of the BS posterior temporalis. In contrast, changes in relative WS and BS activity levels across mammals are not correlated with Triplets I and II. Results from this work can be integrated with dietary and morphological data to better understand how feeding and the masticatory apparatus have evolved across mammals in the context of new masticatory demands.
Identifier
An unambiguous reference to the resource within a given context
<a href="http://doi.org/10.1093/icb/icr068" target="_blank" rel="noreferrer noopener">10.1093/icb/icr068</a>
Format
The file format, physical medium, or dimensions of the resource
Journal Article
2011
alpacas
Crompton A W
discrete characters
Doherty A H
Electromyography
emg
fusion
Hylander W L
Integrative and comparative biology
jaw movements
Journal Article
Masseter
masticatory muscles
mechanics
morphology
symphyseal
Vinyard C J
Wall C E
Williams S H
Zoology
-
Text
A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text.
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n/a
Rights
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Pages
E143-E143
Volume
51
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Title
A name given to the resource
Patterns of functional integration in the mammalian masticatory apparatus
Publisher
An entity responsible for making the resource available
Integrative and Comparative Biology
Date
A point or period of time associated with an event in the lifecycle of the resource
2011
2011-03
Subject
The topic of the resource
Zoology
Creator
An entity primarily responsible for making the resource
Vinyard C J; Doherty A H; Wall C E; Williams S H; Ross C F; Herring S W; Crompton A W; Hylander W L
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n/a
Format
The file format, physical medium, or dimensions of the resource
Journal Article
2011
Crompton A W
Doherty A H
Herring S W
Hylander W L
Integrative and comparative biology
Journal Article
Ross C F
Vinyard C J
Wall C E
Williams S H
Zoology
-
Text
A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text.
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n/a
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Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Pages
E151-E151
Volume
51
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Title
A name given to the resource
Patterns of jaw-muscle recruitment evolution in mammals
Publisher
An entity responsible for making the resource available
Integrative and Comparative Biology
Date
A point or period of time associated with an event in the lifecycle of the resource
2011
2011-03
Subject
The topic of the resource
Zoology
Creator
An entity primarily responsible for making the resource
Williams S H; Vinyard C J; Crompton A W; Hylander W L
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An unambiguous reference to the resource within a given context
n/a
Format
The file format, physical medium, or dimensions of the resource
Journal Article
2011
Crompton A W
Hylander W L
Integrative and comparative biology
Journal Article
Vinyard C J
Williams S H
Zoology
-
Text
A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text.
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n/a
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Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Pages
107-107
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Title
A name given to the resource
The Evolutionary Significance Of Canine Reduction In Hominins: Functional Links Between Jaw Mechanics And Canine Size
Publisher
An entity responsible for making the resource available
American Journal of Physical Anthropology
Date
A point or period of time associated with an event in the lifecycle of the resource
2006
2006
Subject
The topic of the resource
Anthropology; Evolutionary Biology
Creator
An entity primarily responsible for making the resource
Hylander W L; Vinyard C J
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n/a
Format
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Journal Article or Conference Abstract Publication
2006
American journal of physical anthropology
Anthropology
Evolutionary Biology
Hylander W L
Journal Article or Conference Abstract Publication
Vinyard C J
-
Text
A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text.
URL Address
<a href="http://doi.org/10.1002/ajpa.21529" target="_blank" rel="noreferrer noopener">http://doi.org/10.1002/ajpa.21529</a>
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Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Pages
531-547
Issue
4
Volume
145
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Title
A name given to the resource
Functional And Evolutionary Significance Of The Recruitment And Firing Patterns Of The Jaw Adductors During Chewing In Verreaux's Sifaka (propithecus Verreauxi)
Publisher
An entity responsible for making the resource available
American Journal of Physical Anthropology
Date
A point or period of time associated with an event in the lifecycle of the resource
2011
2011-08
Subject
The topic of the resource
Anthropology; biomechanics; bone-strain; electromyography; Evolutionary Biology; Force; fusion; lemurs lemur-catta; macaca-fascicularis; mandibular symphysis; masseter force; mastication; muscle; primates; strepsirrhines; wishboning
Creator
An entity primarily responsible for making the resource
Hylander W L; Vinyard C J; Wall C E; Williams S H; Johnsonl K R
Description
An account of the resource
Jaw-muscle electromyographic (EMG) patterns indicate that compared with thick-tailed galagos and ring-tailed lemurs, anthropoids recruit more relative EMG from their balancing-side deep masseter, and that this muscle peaks late in the power stroke. These recruitment and firing patterns in anthropoids are thought to cause the mandibular symphysis to wishbone (lateral transverse bending), resulting in relatively high symphyseal stresses. We test the hypothesis that living strepsirrhines with robust, partially fused symphyses have muscle recruitment and firing patterns more similar to anthropoids, unlike those strepsirrhines with highly mobile unfused symphyses. Electromyographic (EMG) activity of the superficial and deep masseter, anterior and posterior temporalis, and medial pterygoid muscles were recorded in four dentally adult Verreaux's sifakas (Propithecus verreauxi). As predicted, we find that sifaka motor patterns are more similar to anthropoids. For example, among sifakas, recruitment levels of the balancing-side (b-s) deep masseter are high, and the b-s deep masseter fires late during the power stroke. As adult sifakas often exhibit nearly complete symphyseal fusion, these data support the hypothesis that the evolution of symphyseal fusion in primates is functionally linked to wishboning. Furthermore, these data provide compelling evidence for the convergent evolution of the wishboning motor patterns in anthropoids and sifakas. Am J Phys Anthropol 145:531-547, 2011. (C) 2011 Wiley-Liss, Inc.
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<a href="http://doi.org/10.1002/ajpa.21529" target="_blank" rel="noreferrer noopener">10.1002/ajpa.21529</a>
Format
The file format, physical medium, or dimensions of the resource
Journal Article or Conference Abstract Publication
2011
American journal of physical anthropology
Anthropology
biomechanics
bone-strain
Electromyography
Evolutionary Biology
force
fusion
Hylander W L
Johnsonl K R
Journal Article or Conference Abstract Publication
lemurs lemur-catta
macaca-fascicularis
mandibular symphysis
masseter force
Mastication
Muscle
Primates
strepsirrhines
Vinyard C J
Wall C E
Williams S H
wishboning
-
Text
A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text.
URL Address
<a href="http://doi.org/10.1002/ajpa.20058" target="_blank" rel="noreferrer noopener">http://doi.org/10.1002/ajpa.20058</a>
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Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Pages
35-56
Issue
1
Volume
128
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Title
A name given to the resource
Ternporalis Function In Anthropoids And Strepsirrhines: An Emg Study
Publisher
An entity responsible for making the resource available
American Journal of Physical Anthropology
Date
A point or period of time associated with an event in the lifecycle of the resource
2005
2005-09
Subject
The topic of the resource
adductor muscle force; Anthropology; biomechanics; electromyography; Evolutionary Biology; fusion; galago crassicaudatus; invivo bone strain; jaw-adductor muscle force; macaca-fascicularis; mandibular symphysis; masseter force; mastication; patterns; postorbital septum; primates; temporalis
Creator
An entity primarily responsible for making the resource
Hylander W L; Wall C E; Vinyard C J; Ross C; Ravosa M R; Williams S H; Johnson K R
Description
An account of the resource
The major purpose of this study is to analyze anterior and posterior temporalis muscle force recruitment and firing patterns in various anthropoid and strepsirrhine primates. There are two specific goals for this project. First, we test the hypothesis that in addition to transversely directed muscle force, the evolution of symphyseal fusion in primates may also be linked to vertically directed balancing-side muscle force during chewing (Hylander et al. [2000] Am. J. Phys. Anthropol. 112:469-492). Second, we test the hypothesis of whether strepsirrhines retain the hypothesized primitive mammalian condition for the firing of the anterior temporalis, whereas anthropoids have the derived condition (Weijs [1994] Biomechanics of Feeding in Vertebrates; Berlin: Springer-Verlag, p. 282-320). Electromyographic (EMG) activities of the left and right anterior and posterior temporalis muscles were recorded and analyzed in baboons, macaques, owl monkeys, thick-tailed galagos, and ring-tailed lemurs. In addition, as we used the working-side superficial masseter as a reference muscle, we also recorded and analyzed EMG activity of the left and right superficial masseter in these primates. The data for the anterior temporalis provided no support for the hypothesis that symphyseal fusion in primates is linked to vertically directed jaw muscle forces during mastication. Thus, symphyseal fusion in primates is most likely mainly linked to the timing and recruitment of transversely directed forces from the balancing-side deep masseter (Hylander et al. [2000] Am. J. Phys. Anthropol. 112:469-492). In addition, our data demonstrate that the firing patterns for the working- and balancing-side anterior temporalis muscles are near identical in both strepsirrhines and anthropoids. Their working- and balancing-side anterior temporalis muscles fire asynchronously and reach peak activity during the power stroke. Similarly, their working- and balancing-side posterior temporalis muscles also fire asynchronously and reach peak activity during the power stroke. Compared to these strepsirrhines, however, the balancing-side posterior temporalis of anthropoids appears to have a relatively delayed firing pattern. Moreover, based on their smaller W/B ratios, anthropoids demonstrate a relative increase in muscle-force recruitment of the balancing-side posterior temporalis. This in turn suggests that anthropoids may emphasize the duration and magnitude of the power stroke during mastication. This hypothesis, however, requires additional testing. Furthermore, during the latter portion of the power stroke, the late activity of the balancing-side posterior temporalis of anthropoids apparently assists the balancing-side deep masseter in driving the working-side molars through the terminal portion of occlusion.
Identifier
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<a href="http://doi.org/10.1002/ajpa.20058" target="_blank" rel="noreferrer noopener">10.1002/ajpa.20058</a>
Format
The file format, physical medium, or dimensions of the resource
Journal Article or Conference Abstract Publication
2005
adductor muscle force
American journal of physical anthropology
Anthropology
biomechanics
Electromyography
Evolutionary Biology
fusion
galago crassicaudatus
Hylander W L
invivo bone strain
jaw-adductor muscle force
Johnson K R
Journal Article or Conference Abstract Publication
macaca-fascicularis
mandibular symphysis
masseter force
Mastication
patterns
postorbital septum
Primates
Ravosa M R
Ross C
Temporalis
Vinyard C J
Wall C E
Williams S H