scholarly journals Endocranial and masticatory muscle volumes in myostatin-deficient mice

2014 ◽  
Vol 1 (4) ◽  
pp. 140187 ◽  
Author(s):  
Nathan Jeffery ◽  
Christopher Mendias
Keyword(s):  
Brain Size ◽  
Masticatory Muscles ◽  
Muscle Size ◽  
Masticatory Muscle ◽  
Cavalieri Principle ◽  
Trade Offs ◽  
Contrast Enhanced ◽  
Endocranial Volume ◽  
Deficient Mice ◽  
Total Muscle

Structural and functional trade-offs are integral to the evolution of the mammalian skull and its development. This paper examines the potential for enlargement of the masticatory musculature to limit the size of the endocranial cavity by studying a myostatin-deficient mouse model of hypermuscularity (MSTN−/−). The study tests the null prediction that the larger MSTN−/− mice have larger brains compared with wild-type (WT) mice in order to service the larger muscles. Eleven post-mortem MSTN−/− mice and 12 WT mice were imaged at high resolution using contrast enhanced micro-CT. Masticatory muscle volumes (temporalis, masseter, internal and external pterygoids) and endocranial volumes were measured on the basis of two-dimensional manual tracings and the Cavalieri principle. Volumes were compared using Kruskal–Wallis and Student's t -tests. Results showed that the masticatory muscles of the MSTN−/− mice were significantly larger than in the WT mice. Increases were in the region of 17–36% depending on the muscle. Muscles increased in proportion to each other, maintaining percentages in the region of 5, 10, 21 and 62% of total muscle volume for the external ptyergoid, internal pterygoid, temporalis and masseter, respectively. Kruskal–Wallis and t -tests demonstrated that the endocranial volume was significantly larger in the WT mice, approximately 16% larger on average than that seen in the MSTN−/− mice. This comparative reduction of MSTN−/− endocranial size could not be explained in terms of observer bias, ageing, sexual dimorphism or body size scaling. That the results showed a reduction of brain size associated with an increase of muscle size falsifies the null prediction and lends tentative support to the view that the musculature influences brain growth. It remains to be determined whether the observed effect is primarily physical, nutritional, metabolic or molecular in nature.

Craniofacial Morphology in Myostatin-deficient Mice

2007 ◽  
Vol 86 (11) ◽  
pp. 1068-1072 ◽  
Author(s):  
L. Vecchione ◽  
C. Byron ◽  
G.M. Cooper ◽  
T. Barbano ◽  
M.W. Hamrick ◽  
...  
Keyword(s):  
Masseter Muscle ◽  
Shape Index ◽  
Craniofacial Morphology ◽  
Cranial Vault ◽  
Muscle Size ◽  
Masticatory Muscle ◽  
Wild Type ◽  
Muscle Weight ◽  
Mandibular Body ◽  
Deficient Mice

GDF-8 (myostatin) is a negative growth regulator of skeletal muscle, and myostatin-deficient mice are hypermuscular. Muscle size and force production are thought to influence growth of the craniofacial skeleton. To test this relationship, we compared masticatory muscle size and craniofacial dimensions in myostatin-deficient and wild-type CD-1 control mice. Myostatin-deficient mice had significantly (p < 0.01) greater body (by 18%) and masseter muscle weight (by 83%), compared with wild-type controls. Significant differences (p < 0.05) were noted for cranial vault length, maxillary length, mandibular body length, and mandibular shape index. Significant correlations were noted between masseter muscle weight and mandibular body length (r = 0.68; p < 0.01), cranial vault length (r = −0.57; p < 0.05), and the mandibular shape index (r = −0.56; p < 0.05). Masticatory hypermuscularity resulted in significantly altered craniofacial morphology, probably through altered biomechanical stress. These findings emphasize the important role that masticatory muscle function plays in the ontogeny of the cranial vault, the maxilla, and, most notably, the mandible.

(Preprint)

2018 ◽  
Author(s):  
Dr Malathi Dayalan ◽  
Dr Sudeshna Sharma ◽  
Dr Shweta Poovani ◽  
Dr Saher Altaf
Keyword(s):  
Myofascial Pain ◽  
Mouth Opening ◽  
Masticatory Muscles ◽  
Matched Pair ◽  
Masticatory Muscle ◽  
Muscle Disorders ◽  
Occlusal Contact ◽  
Group I ◽  
Group Ii

BACKGROUND Masticatory system is a complex functional unit, primarily engaged in chewing, swallowing and breathing functions, and some parts are involved in taste recognition and determination of food consistency. Sophisticated functional performances of speech and emotional expressions are specifically human qualities. Irregularities in occlusion appears to be the precipitating factor in the pathogenesis of myofascial pain dysfunction syndrome. Tek- Scan III records the bite length, number, distribution, timing, duration and the relative force of each tooth contact. It also records the sequence of occlusal contacts in terms of time and the associated force with each occlusal contact. The aim of this study was to treat masticatory muscle disorders with occlusal equilibration, and compare the efficacy of treatment outcomes between selective grinding and stabilization splints using Tek-Scan III. OBJECTIVE Objective of this study was to compare the efficacy of occlusal equilibration achieved through selective griding and stabilization splints using Tek-Scan III. METHODS In this in vivo study, 40 patients with masticatory muscle disorders were selected based on the inclusion and exclusion criteria. The occlusal discrepancies were analyzed using Tek-Scan III. The selected 40 subjects were then randomly divided into 2 groups based on the treatment they recieved; Group I – Selective grinding group (20) and Group II – Stabilization splint group (20). Comparison of pre-treatment and post treatment results were evaluated in terms of pain, mouth opening, left and right side force percentage as recorded through Tek-Scan III and reduction of disclusion time. Statistical analysis was carried out with Kolmogorov Smirnov test, Wilcoxon matched pair test and Mann-Whitney U test. RESULTS Wilcoxon matched pairs test demonstrated that there was statistically significant results ( p = 0.0007) in both the groups for reduction of disclusion time, elimination of pain and improved mouth opening. Patients in Group I showed better results as compared to Group II in terms of disclusion time, pain and mouth opening. CONCLUSIONS Occlusal equilibration brought about by reducing the disclusion time using the Tek- Scan III reduced the symptoms of pain in masticatory muscles. Patients in group I (Selective grinding) however showed better results when compared to patients in group II (Stabilization splints).

scholarly journals The energy allocation trade-offs underlying life history traits in hypometabolic strepsirhines and other primates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bruno Simmen ◽  
Luca Morino ◽  
Stéphane Blanc ◽  
Cécile Garcia
Keyword(s):  
Life History ◽  
Energy Expenditure ◽  
Body Mass ◽  
Life History Traits ◽  
Brain Size ◽  
Energy Allocation ◽  
Interbirth Interval ◽  
Energy Investment ◽  
Litter Mass ◽  
Trade Offs

AbstractLife history, brain size and energy expenditure scale with body mass in mammals but there is little conclusive evidence for a correlated evolution between life history and energy expenditure (either basal/resting or daily) independent of body mass. We addressed this question by examining the relationship between primate free-living daily energy expenditure (DEE) measured by doubly labeled water method (n = 18 species), life history variables (maximum lifespan, gestation and lactation duration, interbirth interval, litter mass, age at first reproduction), resting metabolic rate (RMR) and brain size. We also analyzed whether the hypometabolic primates of Madagascar (lemurs) make distinct energy allocation tradeoffs compared to other primates (monkeys and apes) with different life history traits and ecological constraints. None of the life-history traits correlated with DEE after controlling for body mass and phylogeny. In contrast, a regression model showed that DEE increased with increasing RMR and decreasing reproductive output (i.e., litter mass/interbirth interval) independent of body mass. Despite their low RMR and smaller brains, lemurs had an average DEE remarkably similar to that of haplorhines. The data suggest that lemurs have evolved energy strategies that maximize energy investment to survive in the unusually harsh and unpredictable environments of Madagascar at the expense of reproduction.

scholarly journals FEATURES OF MANUFACTURE OF ADVANCED PROVISIONAL BRIDGE-BASED PROSTHESES

2021 ◽  
pp. 33-37
Author(s):  
А. В. Kostyshyn
Keyword(s):  
High Efficiency ◽  
Age Groups ◽  
Masticatory Muscles ◽  
Pathological Process ◽  
Muscle Group ◽  
Control Group ◽  
Masticatory Muscle ◽  
Orthopedic Treatment ◽  
Group 2 ◽  
Reinforcement Model

Abstract. The relevance of the topic is related to the need to improve methods of preparation of dentitions for orthopedic treatment, taking into account the defects of dentitions in patients with reduced occlusion height, taking into account the condition of the masticatory muscles and temporary use of plastic dentures, which provide gradual lifting of occlusion to normalize the masticatory group muscles and reorganization of myostatic reflexes. The aim of the research. Improving the effectiveness of preparation for orthopedic treatment of patients with partial tooth loss, with reduced occlusion height, by improving the design of a temporary bridge-based prosthesis. Materials and methods of research. We examined, treated and conducted clinical observation of 93 patients, who were divided into three groups according to the height of the reduction in occlusion, to achieve this goal and solve problems during the dissertation. Group 1 consisted of 32 patients with included dentition defects with reduced occlusion height up to 2 mm (n=32), group 2 - patients with included dentition defects with reduced occlusion height up to 2-4 mm (n=31), group 3 - these are patients with included dentition defects with reduced occlusion height up to 4-6 mm (n=30). All patients of the main groups belonged to the second and third age groups according to the WHO, aged 35-55 years. The control group (n=30) are young people who belonged to the 1st age group according to the WHO with intact dentition, without concomitant somatic and dental pathology, were admitted in one visit. Also, 123 fiberglass-reinforced plastic prostheses were made. Research results. When drawing up a plan for orthopedic treatment of patients with reduced occlusion height, we took into account possible complications, which are characterized by chipping of the facing material, pathological changes in the temporomandibular joint and masticatory muscle group. We have improved the method of manufacturing non-removable temporary plastic orthopedic constructions by reinforcing with fiberglass tapes and beams, to prevent them and gradually raise the bite. Expanded data on the dynamics of changes in myostatic reflexes and the effectiveness of the use of fixed orthopedic constructions, depending on the pathological process, the timing of adaptation of the masticatory muscle group to orthopedic constructions, according to the degree of reduction in occlusion height. The absence of complaints of breakage and other technical defects of the proposed temporary orthopedic constructions in 100% of cases, successfully allows to use it in the clinic of orthopedic dentistry. A new method of preparing patients for permanent orthopedic treatment by combined reinforcement of temporary non-removable bridge constructions with fiberglass tapes and beams is proposed, which differ in that after preliminary modeling of the frame of the bridge constructions, the technology of double reinforcement, model two support platforms with a step-like transition between them, in which fiberglass tapes and beams are fitted with dental tweezers, after which they are polymerized by the generally accepted method with a photopolymer lamp. Complete the modeling of the constructions and polymerize the prosthesis in the pneumopolymerizer with subsequent grinding and polymerize the prosthesis. Conclusion. The results of the research revealed the high efficiency of the improved method of manufacturing non-removable makeshift plastic of orthopedic constructions.

Brain size/body weight in the dingo (Canis dingo): comparisons with domestic and wild canids

2017 ◽  
Vol 65 (5) ◽  
pp. 292 ◽  
Author(s):  
Bradley P. Smith ◽  
Teghan A. Lucas ◽  
Rachel M. Norris ◽  
Maciej Henneberg
Keyword(s):  
Body Size ◽  
Brain Size ◽  
Cuon Alpinus ◽  
Size Relationship ◽  
Wild Canids ◽  
Free Ranging ◽  
The Impact ◽  
Endocranial Volume ◽  
The Brain

Endocranial volume was measured in a large sample (n = 128) of free-ranging dingoes (Canis dingo) where body size was known. The brain/body size relationship in the dingoes was compared with populations of wild (Family Canidae) and domestic canids (Canis familiaris). Despite a great deal of variation among wild and domestic canids, the brain/body size of dingoes forms a tight cluster within the variation of domestic dogs. Like dogs, free-ranging dingoes have paedomorphic crania; however, dingoes have a larger brain and are more encephalised than most domestic breeds of dog. The dingo’s brain/body size relationship was similar to those of other mesopredators (medium-sized predators that typically prey on smaller animals), including the dhole (Cuon alpinus) and the coyote (Canis latrans). These findings have implications for the antiquity and classification of the dingo, as well as the impact of feralisation on brain size. At the same time, it highlights the difficulty in using brain/body size to distinguish wild and domestic canids.

Relationship Between Masticatory Muscle Size and Bone Regeneration After Mandibular Angle Osteotomy

2021 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Yuanliang Huang ◽  
Liya Yang ◽  
Yanxian Lin ◽  
Lin Mu ◽  
Minghao Zhao ◽  
...  
Keyword(s):  
Bone Regeneration ◽  
Muscle Size ◽  
Masticatory Muscle ◽  
Mandibular Angle

scholarly journals Do Different Methods Yield Equivalent Estimations of Brain Size in Birds?

2020 ◽  
Vol 95 (2) ◽  
pp. 113-122
Author(s):  
Diego Ocampo ◽  
César Sánchez ◽  
Gilbert Barrantes
Keyword(s):  
Body Size ◽  
Brain Size ◽  
Brain Mass ◽  
Wide Range ◽  
Evolutionary Studies ◽  
Relative Brain Size ◽  
Using Data ◽  
Endocranial Volume ◽  
The Brain ◽  
Size Estimates

The ratio of brain size to body size (relative brain size) is often used as a measure of relative investment in the brain in ecological and evolutionary studies on a wide range of animal groups. In birds, a variety of methods have been used to measure the brain size part of this ratio, including endocranial volume, fixed brain mass, and fresh brain mass. It is still unclear, however, whether these methods yield the same results. Using data obtained from fresh corpses and from published sources, this study shows that endocranial volume, mass of fixed brain tissue, and fresh mass provide equivalent estimations of brain size for 48 bird families, in 19 orders. We found, however, that the various methods yield significantly different brain size estimates for hummingbirds (Trochilidae). For hummingbirds, fixed brain mass tends to underestimate brain size due to reduced tissue density, whereas endocranial volume overestimates brain size because it includes a larger volume than that occupied by the brain.

scholarly journals Brain size is correlated with endangerment status in mammals

2016 ◽  
Vol 283 (1825) ◽  
pp. 20152772 ◽  
Author(s):  
Eric S. Abelson
Keyword(s):  
Brain Size ◽  
Extinction Risk ◽  
Small Body ◽  
Cost Benefit ◽  
Metabolic Cost ◽  
Trade Offs ◽  
Extant Species ◽  
Body Sizes ◽  
The Cost ◽  
The Relationship

Increases in relative encephalization (RE), brain size after controlling for body size, comes at a great metabolic cost and is correlated with a host of cognitive traits, from the ability to count objects to higher rates of innovation. Despite many studies examining the implications and trade-offs accompanying increased RE, the relationship between mammalian extinction risk and RE is unknown. I examine whether mammals with larger levels of RE are more or less likely to be at risk of endangerment than less-encephalized species. I find that extant species with large levels of encephalization are at greater risk of endangerment, with this effect being strongest in species with small body sizes. These results suggest that RE could be a valuable asset in estimating extinction vulnerability. Additionally, these findings suggest that the cost–benefit trade-off of RE is different in large-bodied species when compared with small-bodied species.

MUSCLE BULGING REDUCES MUSCLE FORCE AND LIMITS THE MAXIMAL EFFECTIVE MUSCLE SIZE

2006 ◽  
Vol 06 (03) ◽  
pp. 229-239 ◽  
Author(s):  
KARL DAGGFELDT
Keyword(s):  
Muscle Force ◽  
Muscle Length ◽  
Biomechanical Model ◽  
Muscle Performance ◽  
Muscle Size ◽  
Intramuscular Pressure ◽  
Shortening Velocity ◽  
Muscle Shortening ◽  
Force Reduction ◽  
Total Muscle

A biomechanical model was generated in order to investigate the possible mechanisms behind reductions in muscle performance due to muscle bulging. It was shown that the proportion of fiber force contributing to the total muscle force is reduced with fiber bulging and that the cause of this reduction is due to the intramuscular pressure (IMP) created by the bulging fibers. Moreover, it was established that the amount of IMP generated muscle force reduction is determined by the extent to which muscle thickening restricts muscle fibers from shortening, thereby limiting their power contribution. It was shown that bulging can set a limit to the maximal size a muscle can take without losing force and power producing capability. Possible effects, due to bulging, on maximal muscle force in relation to both muscle length and muscle shortening velocity were also demonstrated by the model.

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