scholarly journals Comparative skull biomechanics in Varanus and Salvator ‘Tupinambis’

2017 ◽  
Author(s):  
Hugo Dutel ◽  
Alana C Sharp ◽  
Marc E H Jones ◽  
Susan E Evans ◽  
Micheal J Fagan ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Feeding Behaviour ◽  
Micro Computed Tomography ◽  
Lizard Species ◽  
Element Analysis ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Computer Based ◽  
Morphological Differences

The lizard species Salvator ‘Tupinambis’ merianae and Varanus ornatus evolved independently in South America and Africa but share similar ecology and feeding behaviour, despite having notable differences in their skull structure. Tupinambis has a compact, relatively short and wide snout, whereas that of Varanus is more slender and narrow. In addition, a postorbital bar (POB) is present in Tupinambis but absent in Varanus, and the former lacks the mid-frontal suture that is present in the latter. Here, we explore the biomechanical significance of these differences using 3D computer-based mechanical simulations based on micro-computed tomography, detailed muscle dissections, and in vivo data. First, we simulated muscle activity and joint-reaction forces during biting using Multibody Dynamics Analysis. Then, the forces calculated from these models were used as an input for Finite Element Analysis, to investigate and compare the strains of the skull in these two species. The effects of the presence/absence of structures, such as the POB, were investigated by constructing artificial models which geometry was altered. Our results indicate that strains in the skull bones are lower in Tupinambis than in Varanus, in particular at the back of the skull. The presence of a POB clearly reduces the strains in the bones during posterior biting in Tupinambis, but not in Varanus. Our results hence highlight how the morphological differences between these two taxa affect the mechanical behaviour of their respective skulls during feeding.

scholarly journals Comparative skull biomechanics in Varanus and Salvator ‘Tupinambis’

2017 ◽  
Author(s):  
Hugo Dutel ◽  
Alana C Sharp ◽  
Marc E H Jones ◽  
Susan E Evans ◽  
Micheal J Fagan ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Feeding Behaviour ◽  
Micro Computed Tomography ◽  
Lizard Species ◽  
Element Analysis ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Computer Based ◽  
Morphological Differences

The lizard species Salvator ‘Tupinambis’ merianae and Varanus ornatus evolved independently in South America and Africa but share similar ecology and feeding behaviour, despite having notable differences in their skull structure. Tupinambis has a compact, relatively short and wide snout, whereas that of Varanus is more slender and narrow. In addition, a postorbital bar (POB) is present in Tupinambis but absent in Varanus, and the former lacks the mid-frontal suture that is present in the latter. Here, we explore the biomechanical significance of these differences using 3D computer-based mechanical simulations based on micro-computed tomography, detailed muscle dissections, and in vivo data. First, we simulated muscle activity and joint-reaction forces during biting using Multibody Dynamics Analysis. Then, the forces calculated from these models were used as an input for Finite Element Analysis, to investigate and compare the strains of the skull in these two species. The effects of the presence/absence of structures, such as the POB, were investigated by constructing artificial models which geometry was altered. Our results indicate that strains in the skull bones are lower in Tupinambis than in Varanus, in particular at the back of the skull. The presence of a POB clearly reduces the strains in the bones during posterior biting in Tupinambis, but not in Varanus. Our results hence highlight how the morphological differences between these two taxa affect the mechanical behaviour of their respective skulls during feeding.

Influence of the Musculotendon Dynamics on the Muscle Force-Sharing Problem of the Shoulder—A Fully Inverse Dynamics Approach

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Quental Carlos ◽  
Azevedo Margarida ◽  
Ambrósio Jorge ◽  
Gonçalves S. B. ◽  
Folgado João
Keyword(s):  
Muscle Activation ◽  
Inverse Dynamics ◽  
Glenohumeral Joint ◽  
Inverse Dynamic ◽  
Force Sharing ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Muscle Activations ◽  
Joint Reaction

Abstract Most dynamic simulations are based on inverse dynamics, being the time-dependent physiological nature of the muscle properties rarely considered due to numerical challenges. Since the influence of muscle physiology on the consistency of inverse dynamics simulations remains unclear, the purpose of the present study is to evaluate the computational efficiency and biological validity of four musculotendon models that differ in the simulation of the muscle activation and contraction dynamics. Inverse dynamic analyses are performed using a spatial musculoskeletal model of the upper limb. The muscle force-sharing problem is solved for five repetitions of unloaded and loaded motions of shoulder abduction and shoulder flexion. The performance of the musculotendon models is evaluated by comparing muscle activation predictions with electromyography (EMG) signals, measured synchronously with motion for 11 muscles, and the glenohumeral joint reaction forces estimated numerically with those measured in vivo. The results show similar muscle activations for all muscle models. Overall, high cross-correlations are computed between muscle activations and the EMG signals measured for all movements analyzed, which provides confidence in the results. The glenohumeral joint reaction forces estimated compare well with those measured in vivo, but the influence of the muscle dynamics is found to be negligible. In conclusion, for slow-speed, standard movements of the upper limb, as those studied here, the activation and musculotendon contraction dynamics can be neglected in inverse dynamic analyses without compromising the prediction of muscle and joint reaction forces.

Tissue Engineered Bone Using Polycaprolactone Scaffolds Made by Selective Laser Sintering

2004 ◽  
Vol 845 ◽  
Author(s):  
J. M. Williams ◽  
A. Adewunmi ◽  
R. M. Schek ◽  
C. L. Flanagan ◽  
P. H. Krebsbach ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Selective Laser Sintering ◽  
Mandibular Condyle ◽  
Computational Design ◽  
Laser Sintering ◽  
Histological Evaluation ◽  
Micro Computed Tomography ◽  
Element Analysis ◽  
Immunocompromised Mice

ABSTRACTPolycaprolactone is a bioresorbable polymer that has potential for tissue engineering of bone and cartilage. In this work, we report on the computational design and freeform fabrication of porous polycaprolactone scaffolds using selective laser sintering, a rapid prototyping technique. The microstructure and mechanical properties of the fabricated scaffolds were assessed and compared to designed porous architectures and computationally predicted properties. Compressive modulus and yield strength were within the lower range of reported properties for human trabecular bone. Finite element analysis showed that mechanical properties of scaffold designs and of fabricated scaffolds can be computationally predicted. Scaffolds were seeded with BMP-7 transduced fibroblasts and implanted subcutaneously in immunocompromised mice. Histological evaluation and micro-computed tomography (μCT) analysis confirmed that bone was generated in vivo. Finally, we have demonstrated the clinical application of this technology by producing a prototype mandibular condyle scaffold based on an actual pig condyle.

Estimation of In-Vivo Quadriceps Forces of the Knee: A Combined In-Vivo Patellofemoral Joint Kinematics Measurement and Finite Element Prediction

2011 ◽  
Author(s):  
Koichi Kobayashi ◽  
Guoan Li
Keyword(s):  
Knee Joint ◽  
Load Transfer ◽  
Weight Bearing ◽  
Knee Oa ◽  
Moment Arms ◽  
Joint Reaction Forces ◽  
Joint Contact ◽  
Reaction Forces ◽  
Knee Pathology

The load transfer mechanics across the patellofemoral (PF) joint during weight-bearing conditions is important for treatment of the knee pathology, such as knee OA, ACL deficiency as well as TKA. Many studies have characterized the PF joint reaction forces using equilibriums of the quadriceps and ground reaction forces at the knee joint [1,2,3]. However, this simplification does not consider other muscle function as well as 3D knee joint contact location when calculate moment arms of the involved forces.

Inverse Dynamic Analysis of Shoulder Muscle Activity During Archery Draw Back

2015 ◽  
Author(s):  
Aviktha Reddy ◽  
Yahia M. Al-Smadi
Keyword(s):  
Muscle Activity ◽  
Inverse Dynamic ◽  
Repetitive Motion ◽  
Inverse Dynamic Analysis ◽  
Shoulder Muscle ◽  
Biomechanical Simulation ◽  
Working Postures ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Joint Reaction

The objective of this study is to conduct biomechanical simulation for a musculoskeletal of archery performance. The simulation aims to find the movement patterns in working postures, the muscle activity and joint reaction forces. The results obtained are discussed and the work presented can help analyze the utilization of various muscles during the performance of the repetitive motion of archery.

scholarly journals Ontogenetic plasticity in cranial morphology is associated with a change in the food processing behavior in Alpine newts

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Daniel Schwarz ◽  
Nicolai Konow ◽  
Laura B. Porro ◽  
Egon Heiss
Keyword(s):  
Food Processing ◽  
High Speed ◽  
Cranial Morphology ◽  
Feeding Apparatus ◽  
Micro Computed Tomography ◽  
Morphological Differences ◽  
Alpine Newt ◽  
Similar Body ◽  
Processing Mechanism

Abstract Background The feeding apparatus of salamanders consists mainly of the cranium, mandible, teeth, hyobranchial apparatus and the muscles of the cranial region. The morphology of the feeding apparatus in turn determines the boundary conditions for possible food processing (i.e., intraoral mechanical reduction) mechanisms. However, the morphology of the feeding apparatus changes substantially during metamorphosis, prompting the hypothesis that larvae might use a different food processing mechanism than post-metamorphic adults. Salamandrid newts with facultative metamorphosis are suitable for testing this hypothesis as adults with divergent feeding apparatus morphologies often coexist in the same population, share similar body sizes, and feed on overlapping prey spectra. Methods We use high-speed videography to quantify the in vivo movements of key anatomical elements during food processing in paedomorphic and metamorphic Alpine newts (Ichthyosaura alpestris). Additionally, we use micro-computed tomography (μCT) to analyze morphological differences in the feeding apparatus of paedomorphic and metamorphic Alpine newts and sort them into late-larval, mid-metamorphic and post-metamorphic morphotypes. Results Late-larval, mid-metamorphic and post-metamorphic individuals exhibited clear morphological differences in their feeding apparatus. Regardless of the paedomorphic state being externally evident, paedomorphic specimens can conceal different morphotypes (i.e., late-larval and mid-metamorphic morphotypes). Though feeding on the same prey under the same (aquatic) condition, food processing kinematics differed between late-larval, mid-metamorphic and post-metamorphic morphotypes. Conclusions The food processing mechanism in the Alpine newt changes along with morphology of the feeding apparatus during ontogeny, from a mandible-based to a tongue-based processing mechanism as the changing morphology of the mandible prevents chewing and the tongue allows enhanced protraction. These results could indicate that early tetrapods, in analogy to salamanders, may have developed new feeding mechanisms in their aquatic environment and that these functional innovations may have later paved the way for terrestrial feeding mechanisms.

scholarly journals The mechanoresponse of bone is closely related to the osteocyte lacunocanalicular network architecture

2020 ◽  
Vol 117 (51) ◽  
pp. 32251-32259
Author(s):  
Alexander Franciscus van Tol ◽  
Victoria Schemenz ◽  
Wolfgang Wagermaier ◽  
Andreas Roschger ◽  
Hajar Razi ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Network Structure ◽  
Network Architecture ◽  
Local Strain ◽  
Bone Adaptation ◽  
Micro Computed Tomography ◽  
Entire Cross Section ◽  
Element Analysis ◽  
3D Network

Organisms rely on mechanosensing mechanisms to adapt to changes in their mechanical environment. Fluid-filled network structures not only ensure efficient transport but can also be employed for mechanosensation. The lacunocanalicular network (LCN) is a fluid-filled network structure, which pervades our bones and accommodates a cell network of osteocytes. For the mechanism of mechanosensation, it was hypothesized that load-induced fluid flow results in forces that can be sensed by the cells. We use a controlled in vivo loading experiment on murine tibiae to test this hypothesis, whereby the mechanoresponse was quantified experimentally by in vivo micro-computed tomography (µCT) in terms of formed and resorbed bone volume. By imaging the LCN using confocal microscopy in bone volumes covering the entire cross-section of mouse tibiae and by calculating the fluid flow in the three-dimensional (3D) network, we could perform a direct comparison between predictions based on fluid flow velocity and the experimentally measured mechanoresponse. While local strain distributions estimated by finite-element analysis incorrectly predicts preferred bone formation on the periosteal surface, we demonstrate that additional consideration of the LCN architecture not only corrects this erroneous bias in the prediction but also explains observed differences in the mechanosensitivity between the three investigated mice. We also identified the presence of vascular channels as an important mechanism to locally reduce fluid flow. Flow velocities increased for a convergent network structure where all of the flow is channeled into fewer canaliculi. We conclude that, besides mechanical loading, LCN architecture should be considered as a key determinant of bone adaptation.

scholarly journals Biomechanics of hip joint: a systematic review

2018 ◽  
Vol 7 (3) ◽  
pp. 1672 ◽  
Author(s):  
Chethan KN ◽  
Shyamasunder Bhat N ◽  
Satish Shenoy B
Keyword(s):  
Hip Joint ◽  
Living Organism ◽  
Upper Body ◽  
Joint Prosthesis ◽  
Load Carrying ◽  
Different Types ◽  
Joint Reaction Forces ◽  
Reaction Forces

Hip joint is the second largest joint in human after knee joint. It is associated with different types of motion which helps in the movement of human body and provide stability. Biomechanics involves the study of movement of living organism. It is important to know and understand the basics of biomechanics of hip joint to define the movement of hip joint along with its load carrying capacity in different day to day activities. Many researchers are worked to know the basics biomechanics of hip joint both in in-vitro and in- vivo conditions. In this paper, it has been reported in detail to know the different biomechanical aspects involved in the hip joint during different movement and also different biomaterials used in the hip joint prosthesis. It is majorly focused on load transmitting by hip joint by upper body to lower body in different activities such as walking, running, stumbling etc. So, these basic understanding helps to understand effectively the joint reaction forces which is acting on hip joint while designing new hip joint prosthesis.  

scholarly journals Cancellous bone adaptation to tibial compression is not sex dependent in growing mice

2010 ◽  
Vol 109 (3) ◽  
pp. 685-691 ◽  
Author(s):  
Maureen E. Lynch ◽  
Russell P. Main ◽  
Qian Xu ◽  
Daniel J. Walsh ◽  
Mitchell B. Schaffler ◽  
...  
Keyword(s):  
Bone Mass ◽  
Mechanical Loading ◽  
Cancellous Bone ◽  
Adaptive Response ◽  
Bone Adaptation ◽  
Micro Computed Tomography ◽  
Element Analysis ◽  
Male And Female ◽  
And Control

Mechanical loading can be used to increase bone mass and thus attenuate pathological bone loss. Because the skeleton's adaptive response to loading is most robust before adulthood, elucidating sex-specific responses during growth may help maximize peak bone mass. This study investigated the effect of sex on the response to controlled, in vivo mechanical loading in growing mice. Ten-week-old male and female C57Bl/6 mice underwent noninvasive compression of the left tibia. Peak loads of −11.5 N were applied, corresponding to +1,200 με at the tibial midshaft in both sexes. Cancellous bone mass, architecture, and dynamic formation in the proximal metaphysis were compared between loaded and control limbs via micro-computed tomography and histomorphometry. The strain environment of the proximal metaphysis during loading was characterized using finite element analysis. Both sexes responded to tibial compression through increased bone mass and altered architecture. Cancellous bone mass and tissue density were enhanced in loaded limbs relative to control limbs in both sexes through trabecular thickening and reduced separation. Changes in mass were due to increased cellular activity in loaded limbs compared with control limbs. Adaptation to loading increased the proportion of load transferred by the cancellous bone in the proximal metaphysis. For all cancellous measures, the response to tibial compression did not differ between male and female mice. When similar strains are engendered in males and females, the adaptive response in cancellous bone to mechanical loading does not depend on sex.

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