Hyoid movements are correlated with contractile patterns of the hyoid musculature during infant feeding
Mayerl CJ; Steer KE; Chava AM; Bond LE; Edmonds CE; Gould FDH; Stricklen BM; Hieronymous TL; Vinyard CJ; German RZ
Integrative And Comparative Biology
2021
2021-03
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
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<a href="http://doi.org/" target="_blank" rel="noreferrer noopener"></a>
Intraskeletal Consistency in Patterns of Vascularity within Bat Limb Bones.
Bone; Chiroptera; Cortical porosity; Micro-CT; Synchrotron
Bats are the only mammals to have achieved powered flight. A key innovation allowing for bats to conquer the skies was a forelimb modified into a flexible wing. The wing bones of bats are exceptionally long and dynamically bend with wingbeats. Bone microarchitectural features supporting these novel performance attributes are still largely unknown. The humeri and femora of bats are typically avascular, with the exception of large-bodied taxa (e.g., pteropodid flying foxes). No thorough investigation of vascular canal regionalization and morphology has been undertaken as historically it has been difficult to reconstruct the 3D architecture of these canals. This study augments our understanding of the vascular networks supporting the bone matrix of a sample of bats (n=24) of variable body mass, representing three families (Pteropodidae (large-bodied, Species=6), Phyllostomidae (medium-bodied, Species=2), and Molossidae (medium-bodied, Species=1)). We employed Synchrotron Radiation-based micro-Computed Tomography (SRμCT) to allow for a detailed comparison of canal morphology within humeri and femora. Results indicated that across selected bats, canal number per unit volume is similar independent of body size. Differences in canal morphometry based on body size and bone type appear primarily related to a broader distribution of the canal network as cortical volume increases. Heavier bats display a relatively rich vascular network of mostly longitudinally-oriented canals that are localized mainly to the mid-cortical and endosteal bone envelopes. Taken together, our results suggest that relative vascularity of the limb bones of heavier bats forms support for nutrient exchange in a regional pattern. This article is protected by copyright. All rights reserved.
Andronowski JM; Cole Mary E; Hieronymous TL; Davis RA; Usher Logan R; Cooper LN
Anatomical Record
2021
2021-06-08
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1002/ar.24694" target="_blank" rel="noreferrer noopener">10.1002/ar.24694</a>
The stabilizing function of the tail during arboreal quadrupedalism.
angular momentum; balance; locomotor biomechanics; primates; Stability
Locomotion on the narrow and compliant supports of the arboreal environment is inherently precarious. Previous studies have identified a host of morphological and behavioral specializations in arboreal animals broadly thought to promote stability when on precarious substrates. Less well-studied is the role of the tail in maintaining balance. However, prior anatomical studies have found that arboreal taxa frequently have longer tails for their body size than their terrestrial counterparts, and prior laboratory studies of tail kinematics and the effects of tail reduction in focal taxa have broadly supported the hypothesis that the tail is functionally important for maintaining balance on narrow and mobile substrates. In the current set of studies, we extend this work in two ways. First, we use a laboratory dataset on three-dimensional segmental kinematics and tail inertial properties in squirrel monkeys (Saimiri boliviensis) to investigate how tail angular momentum is modulated during steady-state locomotion on narrow supports. In the second study, we use a quantitative dataset on quadrupedal locomotion in wild platyrrhine monkeys to investigate how free-ranging arboreal animals adjust tail movements in response to substrate variation, focusing on kinematic measures validated in prior laboratory studies of tail mechanics (including the laboratory data presented). Our laboratory results show that S. boliviensis significantly increase average tail angular momentum magnitudes and amplitudes on narrow supports, and primarily regulate that momentum by adjusting the linear and angular velocity of the tail (rather than via changes in tail posture per se). We build on these findings in our second study by showing that wild platyrrhines responded to the precarity of narrow and mobile substrates by extending the tail and exaggerating tail displacements, providing ecological validity to the laboratory studies of tail mechanics presented here and elsewhere. In conclusion, our data support the hypothesis that the long and mobile tails of arboreal animals serve a biological role of enhancing stability when moving quadrupedally over narrow and mobile substrates. Tail angular momentum could be used to cancel out the angular momentum generated by other parts of the body during steady-state locomotion, thereby reducing whole-body angular momentum and promoting stability, and could be used to mitigate the effects of destabilizing torques about the support should the animals encounter large, unexpected perturbations. Overall, these studies suggest that long and mobile tails should be considered among the fundamental suite of adaptations promoting safe and efficient arboreal locomotion.
Young JW; Chadwell BA; Dunham NT; McNamara A; Phelps T; Hieronymous TL; Shapiro LJ
Integrative And Comparative Biology
2021
2021-05-22
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journalArticle
<a href="http://doi.org/10.1093/icb/icab096" target="_blank" rel="noreferrer noopener">10.1093/icb/icab096</a>
The contractile patterns, anatomy and physiology of the hyoid musculature change longitudinally through infancy.
ontogeny; mammal; feeding; swallowing; ANATOMY; EMG; DEGLUTITION; PHYSIOLOGY; HYOID bone; INFANTS; MAMMAL anatomy; MOTOR unit
All mammalian infants suckle, a fundamentally different process than drinking in adults. Infant mammal oropharyngeal anatomy is also anteroposteriorly compressed and becomes more elongate postnatally. While suckling and drinking require different patterns of muscle use and kinematics, little insight exists into how the neuromotor and anatomical systems change through the time that infants suckle. We measured the orientation, activity and contractile patterns of five muscles active during infant feeding from early infancy until weaning using a pig model. Muscles not aligned with the long axis of the body became less mediolaterally orientated with age. However, the timing of activation and the contractile patterns of those muscles exhibited little change, although variation was larger in younger infants than older infants. At both ages, there were differences in contractile patterns within muscles active during both sucking and swallowing, as well as variation among muscles during swallowing. The changes in anatomy, coupled with less variation closer to weaning and little change in muscle firing and shortening patterns suggest that the neuromotor system may be optimized to transition to solid foods. The lesser consequences of aspiration during feeding on an all-liquid diet may not necessitate the evolution of variation in neuromotor function through infancy.
Mayerl CJ; Steer KE; Chava AM; Bond LE; Edmonds CE; Gould FDH; Stricklen BM; Hieronymous TL; German RZ
Proceedings of the Royal Society B. Biological Sciences
2021
2021-03-10
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1098/rspb.2021.0052" target="_blank" rel="noreferrer noopener">10.1098/rspb.2021.0052</a>