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Muscles, Masticatory

Muscles responsible for mastication or chewing.
They include the muscles of the jaw, such as the masseter, temporalis, pterygoid, and digastric muscles.
These muscles play a crucial role in the mechanics of biting, chewing, and grinding food.
Optimal functioning of the masticatory muscles is essential for proper oral and dental health, as well as overall nutritional intake.
Researchers often study these muscles to understand their biomechanics, physiology, and potential disorders that may impact mastication and oral function.

Most cited protocols related to «Muscles, Masticatory»

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Publication 2011
Arthralgia Buffaloes Cheek Ethics Committees, Research Facial Injuries Headache Mandible Muscles, Masseter Muscles, Masticatory Muscle Tissue Myalgia Occlusal Splints Operative Surgical Procedures Oral Cavity Orofacial Pain Pain Palpation Temporal Muscle Temporomandibular Joint Temporomandibular Joint Disorders
Plane models of 11 mandibles of Cingulata (Table 1), each one corresponding to a different species, were created according to the methodology summarized by Fortuny et al. (2012) (link). The models were created using the ANSYS FEA Package (Ansys Inc.) v.15 for Windows 7 (64-bit system) to obtain the von Mises stress distribution.
Two main masticatory muscles (i.e., temporalis and masseter) were included in the model as a vector between the centroid of the muscular attachment in the mandible and the centroid of the equivalent muscle attachment in the skull following the modelling approach used in Serrano-Fochs et al. (2015) (link). To compare the models, a scaling of the values of the forces was applied according to a quasi-homothetic transformation in the FEA models (Marcé-Nogué et al., 2013 ) using the plane model of Chaetophractus villosus as a reference. This method corresponds to an adaptation of the scaling methods proposed by Wroe, McHenry & Thomason (2005) (link) and Dumont, Grosse & Slater (2009) (link) for plane models. This procedure was performed to apply the appropriate force in each model, thus allowing the comparison of the stress results when the specimens differ in size.
The information for each analysed species regarding the area of the mandible, insertion areas, forces (musculature applied force per unit area (N/mm2)), thickness and the scale factor in the quasi-homothetic transformation can be found in Table 1.
The boundary conditions were defined and placed to represent the loads, displacements, and constraining anchors that the structure (i.e., mandible) experiences during its function. The mandible was constrained in the x and y direction at the most anterior part and fixed in the x and y directions on the condyle at the level of the mandibular notch (Fig. 1) following the procedures described in Serrano-Fochs et al. (2015) (link) and Marcé-Nogué et al. (2016) .
Isotropic and linear elastic properties were assumed for the bone. In the absence of data for Cingulata or any other closer relative, as well as lacking data for any mammalian clade with a similarly shaped jaw, we decided to apply the mandibular material properties of Macaca rhesus: E (Elasticity Modulus) = 21,000 MPa and v (Poisson coefficient) = 0.45 (Dechow & Hylander, 2000 (link)). We chose the available properties of Macaca rhesus because it has a wide range of habitats and diet which resembles omnivorous or generalist insectivorous armadillos (Richard, Goldstein & Dewar, 1989 (link)). In addition, it has been shown that in a comparative analysis these values are not crucial (See Gil, Marcé-Nogué & Sánchez, 2015 for discussion).
As primary data, we obtained the von Mises stress distribution of each one of the analysed species. Von Mises stress is an isotropic criterion used to predict the yielding of ductile materials determining an equivalent state of stress (Reddy, 2008 ). Considering bone as a ductile material (Dumont, Grosse & Slater, 2009 (link)) and according to Doblaré, García & Gómez (2004) (link) when isotropic material properties are defined in cortical bone, the von Mises criterion is the most adequate for comparing stress states.
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Publication 2017
Acclimatization Armadillos Bones Cingulata Cloning Vectors Compact Bone Condyle Cranium Diet Displacement, Psychology General Practitioners Insectivora Macaca mulatta Mammals Mandible Muscles, Masseter Muscles, Masticatory Muscle Tissue Temporal Muscle
The generated model yielded a total of 1,854,710 tetrahedral elements with 350,289 nodes, and was imported into a FEA program ABAQUS 6.9 (ABAQUS Inc, Providence, RI). Dentine, pulp, enamel, periodontal ligament, dental follicle, cortical bone and cancellous bone were assigned relevant mechanical properties as indicated in Table 1, according to values established in the literature [53] (link), [63] (link)–[66] (link). Please note that although the mechanical properties of bone do vary according to the direction of force applied, these differences are nonetheless fairly small in all three directions [67] (link), [68] (link) and to a considerable extent lead to very close agreement between experimental and numerical results [64] (link), [69] (link). For this reason, use of linear isotropic elastic properties seems justifiable in anatomical modelling under physiological loading [70] (link). As such, tissues were treated as homogeneous, isotropic and linearly elastic materials.
Sites for attachment of masticatory muscles were defined according to the established anatomical literature, in which the force from the following muscles was modelled: superficial and deep masseter; anterior, middle and posterior fascicles of temporalis; medial and lateral pterygoid; and the anterior belly of the digastric [71] , [72] (link) (Figure 3).
The temporomandibular joint is comparatively resilient, with the condyle impacting against a fibrous articular disk in the anterior region, and articular ligament material in the posterior region. To model this, two blocks of cortical bone were positioned on the articular surfaces of condyles, and the space in-between filled by a 2 mm thick layer of elastic material (Figure 3), while the mechanical properties assigned to the anterior and posterior parts of this area were analogous to the anterior and posterior articular joint materials as indicated in Table 1[64] (link), [66] (link).
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Publication 2013
Bones Cancellous Bone Cardiac Arrest Compact Bone Condyle Dental Enamel Dental Pulp Dental Sac Dentin Fibrosis Joints Ligaments, Articular Meniscus Muscles, Masseter Muscles, Masticatory Muscle Tissue Neocortex Periodontal Ligament physiology Posterior Fascicle Temporal Muscle Temporomandibular Joint Tissues
The muscles applied to the finite element models in this study were limited to the muscles primarily responsible for closing the jaw during biting: anterior temporalis, superficial and deep masseter and medial pterygoid. The muscle force data were derived from physiological cross sectional area data (PCSA), which were obtained from the dissection of a female chimpanzee (see Table 3, Strait et al., 2009 (link)). These data were not scaled by experimental electromyographic (EMG) data because at the time of this FE study, in vivo feeding experiments had not yet been completed for chimpanzees, and thus these data were not available. Because of this, muscle forces were modeled as bilaterally symmetric and at peak (100%) activity level, which approximates maximal static biting. Resulting strain and reaction force magnitudes therefore represent the maximum values that are allowable physiologically, and likely exceed those present in life. However, prior studies (Ross et al., 2005 ; Strait et al., 2009 (link)) demonstrate that the effect of using bilaterally symmetrical forces has a minimal effect on the spatial distribution of strain concentrations, except insofar as strain magnitudes in certain balancing side regions are disproportionately high; strain distributions on the working side are largely unaffected. Fitton et al. (2012) (link) have further demonstrated that strain and deformation patterns are very conservative in the face of variation in muscle force activity.
Muscle forces were applied in all models by scaling the PCSA values by the bone volume of each model to the 2/3 power. This procedure ensures that larger models experience larger muscle forces; however the purpose of this approach is not to estimate true muscle forces in each of our models, since it is known that muscle PCSA scales with positive allometry to body mass (Perry and Wall, 2008 ). Rather, this scaling procedure allows us to eliminate size as a variable affecting strains. Thus, the differences in strain in our models only reflect differences in cranial shape and do not reflect differences in cranial size (Dumont et al., 2009 ). This allows for an assessment of the effect of shape on structural strength. In order to more closely approximate physiological loading, all of the models were loaded using the tangential plus traction function of BoneLoad, a program that simulates the physiological wrapping of muscle around rigid bony structures and extrapolates muscle forces to vectors (Grosse et al., 2007 ). Areas of muscle origin were modeled as force plates and focal coordinates were chosen by selecting insertion points for the muscles of mastication on the surface file of a mandible attached to the modeled cranium, using muscle markings as a guide. This had the effect of directing the force vectors for each muscle to run from origin to insertion.
Publication 2014
Bones Cloning Vectors Cranium Dissection Face Females Human Body Mandible Muscle Rigidity Muscles, Masseter Muscles, Masticatory Muscle Tissue Pan troglodytes Physiological Processes physiology Simulate composite resin Strains Temporal Muscle Traction

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Publication 2011
Buffaloes Cheek Facial Injuries Headache Mandible Muscles, Masseter Muscles, Masticatory Muscle Tissue Occlusal Splints Operative Surgical Procedures Oral Cavity Orofacial Pain Pain Palpation Temporal Muscle Temporomandibular Joint Temporomandibular Joint Disorders

Most recents protocols related to «Muscles, Masticatory»

Male C.B-17/Icr-+/+Jcl mice were purchased from CLEA Japan (Tokyo, Japan). Eighty-one mice were divided into three groups: sham (3 mice), middle cerebral artery occlusion (MCAO) + non-exercise (39 mice), and MCAO + exercise (39 mice). Four MCAO + non-exercise mice and five MCAO + exercise mice died owing to a reduction in food intake that was caused by surgical invasion of the masticatory muscles; hence, these mice were excluded from the experiments. One MCAO + exercise mouse was excluded from the experiments because of its unusual vascular structure. The detailed number of mice in each experiment is indicated in each figure legend. All animal experiments were approved by the Animal Care and Use Committee of Ritsumeikan University, Biwako Kusatsu Campus. We used as few animals as possible and always minimized their suffering.
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Publication 2023
Animals Blood Vessel Eating Males Mice, House Mice, Inbred ICR Middle Cerebral Artery Occlusion Muscles, Masticatory Operative Surgical Procedures
To capture electromyographic signals from the masseter and temporal muscles, a Myosystem-Br1 P84 portable electromyograph (DataHominis Tec. Ltd, Brazil) was used. Differential simple active electrodes and a reference electrode on the wrist consisting of an oval stainless-steel plate, 45 mm long, 30 mm wide, and 1 mm thick, wrapped in plastic, were used.
Before placing the electrodes, the skin was cleaned with alcohol to eliminate grease and pollution residues. The electrodes were positioned by the same trained examiner. To ensure the correct location of the masticatory muscles, specific maneuvers of maximal voluntary contraction were performed, accompanied by digital palpation, according to the recommendations of the surface EMG for non-invasive assessment of muscles (SENIAM) project [12 (link)].
Electromyographic activity (microvolts) was evaluated during mandibular rest (4 s), protrusion (10 s), right laterality (10 s), left laterality (10 s), and dental clenching during maximum voluntary contraction (4 s). During the recording of electromyographic activities, the environment was kept calm and silent, with patients seated in a comfortable chair, upright posture, soles of the feet resting on the ground, and hands resting on the thighs. The head was positioned with the Frankfurt horizontal plane parallel to the ground [13 (link)].
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Publication 2023
Dental Health Services Electromyography Ethanol Fingers Foot Head Mandible Muscles, Masseter Muscles, Masticatory Muscle Tissue Palpation Patients Skin Stainless Steel Surface Electromyography Temporal Muscle Thigh Wrist
A double-blinded, interventional, non-randomized control trial was conducted in the Aligarh Province (Uttar Pradesh, India) between 2017 and 2019. This study aimed to evaluate the role of vitamin D on masticatory muscle activity among completely edentulous patients and its effect on the retention of dentures as perceived by patients. The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Ethics Committee of the Institute. JNMC, AMU, Aligarh, India [JNMC-AMU/ECL/22-2013-14]. The study protocol was developed, and all subjects gave their written informed consent for inclusion before they participated in the study.
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Publication 2023
Denture Retention Ergocalciferol Ethics Committees Muscles, Masticatory Patients
To test our first and second hypotheses, maximum bite forces were simulated. In order to obtain maximum bite forces that were comparable at each gape, the temporo-mandibular joint (TMJ) was modelled as a revolute joint (only permitting rotation in one degree of freedom). The DGO was set to follow a motion which opened the jaw to a distance of approximately 15.5 mm between the incisors, and then closed it again. Although no in vivo data on squirrel jaw motion during feeding currently exists in the published literature, studies of other rodents [34 (link),35 (link)] suggest that, during the power stroke of incision, mandibular motion is largely constrained to the vertical axis. Thus, the use of a revolute TMJ, producing a simple hinge movement of the mandible, was felt to be a reasonable approximation of incision in the squirrel. By contrast, mastication at the molar teeth in rodents involves a much wider range of highly complex jaw movements in all three axes. Without further experimental information on squirrels, it was felt that maximal molar biting could not be realistically simulated in our MDA models and so was not included in the analyses here (but see section below on non-maximal molar biting).
To simulate a maximum bite force, the translational spring damper was set with a high stiffness in each orthogonal direction, so that the food bolus did not deform. Maximum incisor bite force was calculated using three different sizes of food bolus: 2, 7.5 and 15 mm. The largest bolus size was chosen to represent the approximate diameter of a hazelnut. The smaller sizes are an acknowledgement that squirrels do not generally bite across the widest point of a nut, but rather gnaw with multiple, smaller bites.
In order to investigate how each masticatory muscle contributes to incisor biting, maximum incisor bites were calculated in a series of simulations, whereby in each simulation the activation of each bilateral pair of muscles was set to zero. This represented a ‘virtual ablation’ of each pair of muscles, as has been undertaken previously in finite-element analysis studies (e.g. [13 ,61 (link),62 (link)]). The maximum incisor bite force calculated in each simulation was then used to determine the percentage reduction in force, when compared to the maximum incisor bite force generated with all muscles active. The percentage reduction in bite force was compared across gapes to determine whether each pair of muscles performs better at narrow or wide gapes. In addition, the percentage reduction in bite force was also compared to the muscle's percentage contribution to total adductor force (table 1, as determined from muscle PCSA) to investigate if each muscle ‘overperforms’ or ‘underperforms’ relative to the theoretical maximum force it can produce.
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Publication 2023
Bites Cerebrovascular Accident Chewing Dental Occlusion Epistropheus Feelings Food Hazelnuts Incisor Joints Mandible Molar Movement Muscles, Masticatory Muscle Tissue Protein Biosynthesis Rodent Squirrels Temporomandibular Joint
MDA models of the red and grey squirrel heads were created by importing the virtual reconstructions of the cranium and mandible to Adams View v. 2021 (MSC Software Corp., Irvine, CA, USA). The mass and inertial properties of the mandible were calculated based on volume and a standard tissue density of 1.05 g cm−3 [59 (link)]. The jaw-closing muscles, as listed above and in table 1, were added to the model. Each jaw adductor was modelled as a series of strands in order to capture the differing fibre directions present within a single muscle (figure 1). The masticatory system was completed by including a jaw opener (digastric muscle). Muscle wrapping was employed to enable accurate fibre excursions and to prevent muscle–bone and muscle–muscle intersections. This was particularly important for modelling the superficial masseter, anterior deep masseter, temporalis, lateral pterygoid and digastric.

MDA model of the (a) red squirrel skull in right lateral view; and the grey squirrel skull in (b) right lateral; (c) ventral; and (d) frontal views. Muscles represented by coloured strands: sky blue, superficial masseter; royal blue, anterior deep masseter; midnight blue, posterior deep masseter; light green, anterior ZM; dark green, posterior ZM; red, temporalis; orange, medial pterygoid; yellow, lateral pterygoid; brown, digastric. Scale bar = 10 mm.

Biting was simulated through modelling a food bolus positioned between the cranium and mandible on the right side. The food bolus was modelled as two rigid plates separated by a translational spring damper which connected the two plates at a coincident location. A contact with a high friction coefficient was defined between the lower plate and the mandible to ensure there was minimal displacement between the two. The translational spring damper was defined with three orthogonal forces, all of which were proportional to the distance between the two plates. The height and position of the food bolus were both adjustable in order to simulate biting at gapes.
The muscles were activated through the application of a Dynamic Geometric Optimization (DGO) method [60 (link)], which estimates the muscle forces (taking into account the instantaneous strand orientations) to make the mandible follow a specific motion (see below). Each muscle was assigned a maximum muscle force (table 1), along with a small passive tension that is naturally developed in resistance to their elongation. A maximum passive tension of 0.15 N was assigned to each muscle strand to provide resistance during jaw opening and closing [60 (link)]. This passive tension was the same in all simulations for comparative purposes. Although consideration of the length-tension curve of the masticatory muscles would provide a greater degree of accuracy in the muscle forces applied across the jaw closing cycle, this data does not currently exist for squirrels. Moreover, previous research on rats [33 (link)] concluded that changes in isometric tension over the range of muscle extension generated during feeding would be very small. We believe this holds true for the squirrel models here as the maximum muscle stretch (approximately 35% in the anterior deep masseter) is similar to that reported in the rat (30% [33 (link)]).
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Publication 2023
Bones Cranium Fibrosis Food Friction Head Intersectional Framework Mandible Masticatory System Mental Orientation Methyl Green Muscle Rigidity Muscles, Masseter Muscles, Masticatory Muscle Tissue Protein Biosynthesis Reconstructive Surgical Procedures Squirrels Temporal Muscle Tissues

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More about "Muscles, Masticatory"

Chewing Muscles, Jaw Muscles, Masticatory Apparatus, Mastication Muscles, Masticatory System, Mandibular Muscles, Oral Muscles, Stomatognathic System.
The masticatory muscles, including the masseter, temporalis, pterygoid, and digastric muscles, play a crucial role in the mechanics of biting, chewing, and grinding food.
Optimal functioning of these muscles is essential for proper oral and dental health, as well as overall nutritional intake.
Researchers often study the biomechanics, physiology, and potential disorders of the masticatory muscles using tools like SPSS Statistics 22, SigmaStat version 3.5, and the Pain Test™ Model FPK.
Innovative platforms like PubCompare.ai utilize AI-driven comparisons to help identify the best research protocols and products for masticatory muscle studies, enhancing reproducibility and accuracy.
Understanding the masticatory system, including the use of BALB/c mice, Ketalar, Rompun, and the High-Capacity cDNA Reverse Transcription Kit, is crucial for maintaining overall oral health and function.