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Greg M Murray - One of the best experts on this subject based on the ideXlab platform.
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single motor units from the medial Pterygoid Muscle can be active during isometric horizontal and vertical forces
Journal of Oral Rehabilitation, 2019Co-Authors: Yalda Nozad Mojaver, Paul B Tawadros, Polyana Moura Ferreira, Terry Whittle, Greg M MurrayAbstract:OBJECTIVES: To determine (a) whether the medial Pterygoid Muscle is active in an isometric vertical force task and in isometric horizontal force tasks in the contralateral, protrusion and ipsilateral directions; (b) whether the same single motor units (SMUs) could be active across different directions of isometric force generation; and (c) whether different regions of the medial Pterygoid Muscle exhibit different patterns of SMU activation during the generation of any one direction of isometric force. METHODS: Intramuscular electromyographic (EMG) recordings were made from the right medial Pterygoid Muscle in 15 healthy participants during isometric force tasks: vertical and horizontal contralateral, protrusion and ipsilateral. A computed tomography scan divided the EMG recording site into a medial or lateral part in each participant. Single motor units were discriminated in each task. RESULTS: Medial Pterygoid SMU activity was recorded in 100% of participants for the vertical biting tasks, 86% of participants for the horizontal contralateral and horizontal protrusion tasks and 57% of the horizontal ipsilateral tasks. Of the 72 SMUs that were discriminated, 36% were active in all tasks; 18% were active only in the vertical tasks and 17% were active in the vertical, horizontal contralateral and horizontal protrusion tasks. The proportion of SMUs that was active in at least 1 horizontal task in the lateral part (33/39) was significantly higher than the proportion (21/33) in the medial part (Chi-Square, P < 0.05). CONCLUSION: The data are consistent with a stabilisation role for the medial Pterygoid Muscle in isometric jaw forces in the vertical and horizontal planes.
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the medial Pterygoid Muscle a stabiliser of horizontal jaw movement
Journal of Oral Rehabilitation, 2017Co-Authors: Hui Chen, Greg M Murray, Terry Whittle, John Gal, Iven KlinebergAbstract:There is limited information of the normal function of the human medial Pterygoid Muscle (MPt). The aims were to determine whether (i) the MPt is active throughout horizontal jaw movements with the teeth apart and (ii) whether single motor units (SMUs) are active during horizontal and opening-closing jaw movements. Intramuscular electrodes were placed in the right MPt of 18 participants who performed five teeth-apart tasks: (i) postural position, (ii) ipsilateral (i.e. right) jaw movement, (iii) contralateral movement, (iv) protrusive movement and (v) opening-closing movement. Movement tasks were guided by a target and were divided into BEFORE, OUT, HOLDING, RETURN and AFTER phases according to the movement trajectories recorded by a jaw tracking system. Increased EMG activity was consistently found in the OUT, HOLDING and RETURN phases of the contralateral and protrusive movement tasks. An increased RETURN phase activity in the ipsilateral task indicates an important role for the MPt in the contralateral force vector. Of the 14 SMUs active in the opening-closing task, 64% were also active in at least one horizontal task. There were tonically active SMUs at the postural jaw position in 44% of participants. These new data point to an important role for the MPt in the fine control of low forces as required for stabilisation of vertical mandibular position not only to maintain postural position, but also throughout horizontal jaw movements with the teeth apart. These findings provide baseline information for future investigations of the possible role of this Muscle in oro-facial pain conditions.
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the medial Pterygoid Muscle a stabiliser of horizontal jaw movement
Journal of Oral Rehabilitation, 2017Co-Authors: Hui Chen, Greg M Murray, Terry Whittle, Iven KlinebergAbstract:There is limited information of the normal function of the human medial Pterygoid Muscle (MPt). The aims were to determine whether (a) the MPt is active throughout horizontal jaw movements with the teeth apart and (b) whether single motor units (SMUs) are active during horizontal and opening - closing jaw movements. Intramuscular electrodes were placed in the right MPt of 18 participants who performed 5 teeth-apart tasks: 1) postural position, 2) ipsilateral (i.e. right) jaw movement, 3) contralateral movement, 4) protrusive movement, 5) opening–closing movement. Movement tasks were guided by a target and were divided into BEFORE, OUT, HOLDING, RETURN and AFTER phases according to the movement trajectories recorded by a jaw tracking system. Increased EMG activity was consistently found in the OUT, HOLDING and RETURN phases of the contralateral and protrusive movement tasks. An increased RETURN phase activity in the ipsilateral task indicates an important role for the MPt in the contralateral force vector. Of the 14 SMUs active in the opening-closing task, 64% were also active in at least 1 horizontal task. There were tonically active SMUs at the postural jaw position in 44% of participants. These new data point to an important role for the MPt in the fine control of low forces as required for stabilization of vertical mandibular position not only to maintain postural position, but also throughout horizontal jaw movements with the teeth apart. These findings provide baseline information for future investigations of the possible role of this Muscle in orofacial pain conditions. This article is protected by copyright. All rights reserved.
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The Lateral Pterygoid Muscle: Function and Dysfunction
Seminars in Orthodontics, 2012Co-Authors: Greg M MurrayAbstract:The human lateral Pterygoid Muscle plays an important role in the control of jaw movements. This review provides an update on some aspects of the normal function of the lateral Pterygoid Muscle and its response to alterations, including mandibular advancement, occlusal changes, and experimental orofacial pain. Both the upper or superior head (SHLP) and the lower or inferior head (IHLP) of the lateral Pterygoid insert predominantly into the neck of the condyle. A number of recent studies have carried out recordings of jaw movement and electromyographic (EMG) activity from the lateral Pterygoid Muscle, where verification of electrode location has been achieved through computer tomography imaging. From these studies, there is no evidence of background EMG activity within IHLP or SHLP when the jaw is in the clinically determined postural jaw position. There is little evidence for a reciprocal relation in activity between SHLP and IHLP, and both SHLP and IHLP play an important role in contralateral, protrusive, and jaw-opening movements and force generation. There is evidence for independent activation of subcompartments within the lateral Pterygoid Muscle to allow a range of force vectors to be delivered to the condyle. In terms of the role of the lateral Pterygoid Muscle in mandibular advancement and occlusal changes, the lack of studies of these issues, where verified recordings have been made from the lateral Pterygoid Muscle, means that there is no definitive evidence in humans for the "lateral Pterygoid hypothesis," and there is also little reliable information as to the effect of occlusal variables on the activity of the lateral Pterygoid Muscle. There is also little information on the effect of pain on lateral Pterygoid Muscle activity, although recent studies demonstrate that the pattern of pain-induced changes in lateral Pterygoid Muscle EMG activity is not clear-cut but can vary with the task performed and jaw displacement magnitude. The lateral Pterygoid Muscle is a difficult Muscle to access, and only verified recordings from the Muscle will yield definitive conclusions.
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threshold properties of single motor units in superior head of human lateral Pterygoid Muscle
Archives of Oral Biology, 2007Co-Authors: Manish K. Bhutada, Terry Whittle, Christopher C. Peck, I. Phanachet, K. Wanigaratne, Greg M MurrayAbstract:Abstract The superior head of the human lateral Pterygoid Muscle (SHLP) may play a similar role in jaw movement as the inferior head (IHLP). Objective The aim was to determine whether threshold properties of single motor units (SMUs) within SHLP during jaw tasks were comparable to those identified for IHLP. Design In 24 human subjects, SMUs were recorded intramuscularly from computer-tomography verified sites within SHLP during standardised jaw tasks recorded by a jaw-tracking device. Results Of the 69 SMUs discriminated, 54 were active during contralateral, 52 during protrusive and 8 during ipsilateral jaw movements. The thresholds, at which SMUs commenced firing, decreased ( p Conclusions The similarities in SHLP and IHLP functional properties support the proposal that both heads should be regarded as a system of fibers acting as one Muscle.
Terry Whittle - One of the best experts on this subject based on the ideXlab platform.
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single motor units from the medial Pterygoid Muscle can be active during isometric horizontal and vertical forces
Journal of Oral Rehabilitation, 2019Co-Authors: Yalda Nozad Mojaver, Paul B Tawadros, Polyana Moura Ferreira, Terry Whittle, Greg M MurrayAbstract:OBJECTIVES: To determine (a) whether the medial Pterygoid Muscle is active in an isometric vertical force task and in isometric horizontal force tasks in the contralateral, protrusion and ipsilateral directions; (b) whether the same single motor units (SMUs) could be active across different directions of isometric force generation; and (c) whether different regions of the medial Pterygoid Muscle exhibit different patterns of SMU activation during the generation of any one direction of isometric force. METHODS: Intramuscular electromyographic (EMG) recordings were made from the right medial Pterygoid Muscle in 15 healthy participants during isometric force tasks: vertical and horizontal contralateral, protrusion and ipsilateral. A computed tomography scan divided the EMG recording site into a medial or lateral part in each participant. Single motor units were discriminated in each task. RESULTS: Medial Pterygoid SMU activity was recorded in 100% of participants for the vertical biting tasks, 86% of participants for the horizontal contralateral and horizontal protrusion tasks and 57% of the horizontal ipsilateral tasks. Of the 72 SMUs that were discriminated, 36% were active in all tasks; 18% were active only in the vertical tasks and 17% were active in the vertical, horizontal contralateral and horizontal protrusion tasks. The proportion of SMUs that was active in at least 1 horizontal task in the lateral part (33/39) was significantly higher than the proportion (21/33) in the medial part (Chi-Square, P < 0.05). CONCLUSION: The data are consistent with a stabilisation role for the medial Pterygoid Muscle in isometric jaw forces in the vertical and horizontal planes.
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the medial Pterygoid Muscle a stabiliser of horizontal jaw movement
Journal of Oral Rehabilitation, 2017Co-Authors: Hui Chen, Greg M Murray, Terry Whittle, John Gal, Iven KlinebergAbstract:There is limited information of the normal function of the human medial Pterygoid Muscle (MPt). The aims were to determine whether (i) the MPt is active throughout horizontal jaw movements with the teeth apart and (ii) whether single motor units (SMUs) are active during horizontal and opening-closing jaw movements. Intramuscular electrodes were placed in the right MPt of 18 participants who performed five teeth-apart tasks: (i) postural position, (ii) ipsilateral (i.e. right) jaw movement, (iii) contralateral movement, (iv) protrusive movement and (v) opening-closing movement. Movement tasks were guided by a target and were divided into BEFORE, OUT, HOLDING, RETURN and AFTER phases according to the movement trajectories recorded by a jaw tracking system. Increased EMG activity was consistently found in the OUT, HOLDING and RETURN phases of the contralateral and protrusive movement tasks. An increased RETURN phase activity in the ipsilateral task indicates an important role for the MPt in the contralateral force vector. Of the 14 SMUs active in the opening-closing task, 64% were also active in at least one horizontal task. There were tonically active SMUs at the postural jaw position in 44% of participants. These new data point to an important role for the MPt in the fine control of low forces as required for stabilisation of vertical mandibular position not only to maintain postural position, but also throughout horizontal jaw movements with the teeth apart. These findings provide baseline information for future investigations of the possible role of this Muscle in oro-facial pain conditions.
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the medial Pterygoid Muscle a stabiliser of horizontal jaw movement
Journal of Oral Rehabilitation, 2017Co-Authors: Hui Chen, Greg M Murray, Terry Whittle, Iven KlinebergAbstract:There is limited information of the normal function of the human medial Pterygoid Muscle (MPt). The aims were to determine whether (a) the MPt is active throughout horizontal jaw movements with the teeth apart and (b) whether single motor units (SMUs) are active during horizontal and opening - closing jaw movements. Intramuscular electrodes were placed in the right MPt of 18 participants who performed 5 teeth-apart tasks: 1) postural position, 2) ipsilateral (i.e. right) jaw movement, 3) contralateral movement, 4) protrusive movement, 5) opening–closing movement. Movement tasks were guided by a target and were divided into BEFORE, OUT, HOLDING, RETURN and AFTER phases according to the movement trajectories recorded by a jaw tracking system. Increased EMG activity was consistently found in the OUT, HOLDING and RETURN phases of the contralateral and protrusive movement tasks. An increased RETURN phase activity in the ipsilateral task indicates an important role for the MPt in the contralateral force vector. Of the 14 SMUs active in the opening-closing task, 64% were also active in at least 1 horizontal task. There were tonically active SMUs at the postural jaw position in 44% of participants. These new data point to an important role for the MPt in the fine control of low forces as required for stabilization of vertical mandibular position not only to maintain postural position, but also throughout horizontal jaw movements with the teeth apart. These findings provide baseline information for future investigations of the possible role of this Muscle in orofacial pain conditions. This article is protected by copyright. All rights reserved.
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threshold properties of single motor units in superior head of human lateral Pterygoid Muscle
Archives of Oral Biology, 2007Co-Authors: Manish K. Bhutada, Terry Whittle, Christopher C. Peck, I. Phanachet, K. Wanigaratne, Greg M MurrayAbstract:Abstract The superior head of the human lateral Pterygoid Muscle (SHLP) may play a similar role in jaw movement as the inferior head (IHLP). Objective The aim was to determine whether threshold properties of single motor units (SMUs) within SHLP during jaw tasks were comparable to those identified for IHLP. Design In 24 human subjects, SMUs were recorded intramuscularly from computer-tomography verified sites within SHLP during standardised jaw tasks recorded by a jaw-tracking device. Results Of the 69 SMUs discriminated, 54 were active during contralateral, 52 during protrusive and 8 during ipsilateral jaw movements. The thresholds, at which SMUs commenced firing, decreased ( p Conclusions The similarities in SHLP and IHLP functional properties support the proposal that both heads should be regarded as a system of fibers acting as one Muscle.
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The human lateral Pterygoid Muscle
Archives of oral biology, 2006Co-Authors: Greg M Murray, Manish K. Bhutada, Christopher C. Peck, I. Phanachet, Daraporn Sae-lee, Terry WhittleAbstract:One of the jaw Muscles particularly implicated in temporomandibular disorders (TMD), a common form of non-dental chronic orofacial pain, is the human lateral Pterygoid Muscle. The precise role of this Muscle in TMD is unclear as is the nature of the interaction between pain and motor function particularly involving this Muscle. This research group has adopted a two-stage approach to studying the effects of pain on motor function. The first is to study normal orofacial motor function through recordings of jaw movement and electromyographic (EMG) activity from a number of jaw Muscles (including recordings from the lateral Pterygoid Muscle; verification of electrode location achieved through computer tomography imaging) during a number of standardised jaw movements. These studies have defined the detailed functional properties of, in particular, the lateral Pterygoid Muscle, whose physiology and function is not well understood. In summary, the data are consistent with the hypothesis previously proposed that the lateral Pterygoid should be regarded as a system of fibres that acts as one Muscle, with varying amounts of evenly graded activity throughout its entire range, and with the distribution of activity within the Muscle being determined by the biomechanical demands of the task. Our second approach has been to study the effects of experimental masseter Muscle pain on the detailed functional properties (e.g., root-mean-square EMG activity) of the jaw Muscles, especially the lateral Pterygoid Muscle. Preliminary data from these pain studies point towards significant effects of human experimental Muscle pain on jaw Muscle activity and jaw movement.
I. Phanachet - One of the best experts on this subject based on the ideXlab platform.
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threshold properties of single motor units in superior head of human lateral Pterygoid Muscle
Archives of Oral Biology, 2007Co-Authors: Manish K. Bhutada, Terry Whittle, Christopher C. Peck, I. Phanachet, K. Wanigaratne, Greg M MurrayAbstract:Abstract The superior head of the human lateral Pterygoid Muscle (SHLP) may play a similar role in jaw movement as the inferior head (IHLP). Objective The aim was to determine whether threshold properties of single motor units (SMUs) within SHLP during jaw tasks were comparable to those identified for IHLP. Design In 24 human subjects, SMUs were recorded intramuscularly from computer-tomography verified sites within SHLP during standardised jaw tasks recorded by a jaw-tracking device. Results Of the 69 SMUs discriminated, 54 were active during contralateral, 52 during protrusive and 8 during ipsilateral jaw movements. The thresholds, at which SMUs commenced firing, decreased ( p Conclusions The similarities in SHLP and IHLP functional properties support the proposal that both heads should be regarded as a system of fibers acting as one Muscle.
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The human lateral Pterygoid Muscle
Archives of oral biology, 2006Co-Authors: Greg M Murray, Manish K. Bhutada, Christopher C. Peck, I. Phanachet, Daraporn Sae-lee, Terry WhittleAbstract:One of the jaw Muscles particularly implicated in temporomandibular disorders (TMD), a common form of non-dental chronic orofacial pain, is the human lateral Pterygoid Muscle. The precise role of this Muscle in TMD is unclear as is the nature of the interaction between pain and motor function particularly involving this Muscle. This research group has adopted a two-stage approach to studying the effects of pain on motor function. The first is to study normal orofacial motor function through recordings of jaw movement and electromyographic (EMG) activity from a number of jaw Muscles (including recordings from the lateral Pterygoid Muscle; verification of electrode location achieved through computer tomography imaging) during a number of standardised jaw movements. These studies have defined the detailed functional properties of, in particular, the lateral Pterygoid Muscle, whose physiology and function is not well understood. In summary, the data are consistent with the hypothesis previously proposed that the lateral Pterygoid should be regarded as a system of fibres that acts as one Muscle, with varying amounts of evenly graded activity throughout its entire range, and with the distribution of activity within the Muscle being determined by the biomechanical demands of the task. Our second approach has been to study the effects of experimental masseter Muscle pain on the detailed functional properties (e.g., root-mean-square EMG activity) of the jaw Muscles, especially the lateral Pterygoid Muscle. Preliminary data from these pain studies point towards significant effects of human experimental Muscle pain on jaw Muscle activity and jaw movement.
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The human lateral Pterygoid Muscle: a review of some experimental aspects and possible clinical relevance.
Australian dental journal, 2004Co-Authors: Greg M Murray, I. Phanachet, S Uchida, Terry WhittleAbstract:The clinical notion that some disturbance to the activity of the lateral Pterygoid Muscle plays a role in the aetiology of temporomandibular disorders (TMD) is still widely accepted and influences management strategies. However, there is no rigorous scientific evidence to support this clinical notion and the role of the lateral Pterygoid Muscle in normal function is still controversial. The classically defined functions of each head of the Muscle are that the superior head is active on closing, retrusion, and ipsilateral jaw movements, while the inferior head is active on opening, protrusion and contralateral jaw movements. However, recent data indicate that these concepts are too simplistic. For example, recent evidence suggests that parts of the superior head may also be active on opening, protrusion and contralateral jaw movements, and that the superior head may consist of three mediolaterally arranged functional zones. Given these complexities, the proposal that clicking and/or locking conditions arise in the temporomandibular joint through some form of lack of co-ordination between the two heads of the Muscle needs re-evaluation. Despite earlier reports to the contrary, both heads of the lateral Pterygoid Muscle appear to be electrically silent at the postural or resting jaw position, and therefore appear to play no role in the anteroposterior positioning of the jaw at the postural position. An important role has also been demonstrated electromyographically for progressive changes in activity in the inferior head as the direction of horizontal jaw force shifts from one side to the other. This suggests an important role for the lateral Pterygoid Muscle in the generation of side-to-side and protrusive jaw forces. The lateral Pterygoid Muscle is likely therefore to play an important role in parafunctional excursive jaw movements and also possibly a role in influencing jaw position in patients where the maxillomandibular relationship records change from session to session. The above data provide new insights into the normal function of the lateral Pterygoid Muscle. The proposal that the lateral Pterygoid Muscle plays some role in the aetiology of TMD needs now to be rigorously tested.
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Functional properties of single motor units in the inferior head of human lateral Pterygoid Muscle: task firing rates.
Journal of neurophysiology, 2002Co-Authors: I. Phanachet, Terry Whittle, K. Wanigaratne, Greg M MurrayAbstract:The precise function of the inferior head of the human lateral Pterygoid Muscle (IHLP) is unclear. The aim of this study was to clarify the normal function of the IHLP. The hypothesis was that an i...
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Functional properties of single motor units in inferior head of human lateral Pterygoid Muscle: task relations and thresholds.
Journal of neurophysiology, 2001Co-Authors: I. Phanachet, Terry Whittle, K. Wanigaratne, Greg M MurrayAbstract:The aim of this study was to clarify the normal function of the inferior head of the human lateral Pterygoid Muscle (IHLP). The hypothesis was that an important function of the IHLP is in the fine ...
K. Wanigaratne - One of the best experts on this subject based on the ideXlab platform.
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threshold properties of single motor units in superior head of human lateral Pterygoid Muscle
Archives of Oral Biology, 2007Co-Authors: Manish K. Bhutada, Terry Whittle, Christopher C. Peck, I. Phanachet, K. Wanigaratne, Greg M MurrayAbstract:Abstract The superior head of the human lateral Pterygoid Muscle (SHLP) may play a similar role in jaw movement as the inferior head (IHLP). Objective The aim was to determine whether threshold properties of single motor units (SMUs) within SHLP during jaw tasks were comparable to those identified for IHLP. Design In 24 human subjects, SMUs were recorded intramuscularly from computer-tomography verified sites within SHLP during standardised jaw tasks recorded by a jaw-tracking device. Results Of the 69 SMUs discriminated, 54 were active during contralateral, 52 during protrusive and 8 during ipsilateral jaw movements. The thresholds, at which SMUs commenced firing, decreased ( p Conclusions The similarities in SHLP and IHLP functional properties support the proposal that both heads should be regarded as a system of fibers acting as one Muscle.
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functional activity of superior head of human lateral Pterygoid Muscle during isometric force
Journal of Dental Research, 2005Co-Authors: S Ruangsri, Terry Whittle, K. Wanigaratne, Greg M MurrayAbstract:There is controversy as to the jaw tasks for which the superior head of the human lateral Pterygoid Muscle (SHLP) becomes active. The aim was to describe the functional activities of SHLP single motor units (SMUs) during horizontal isometric force tasks. In 11 subjects, 48 SMUs were recorded from computer-tomography-verified SHLP sites during generation of horizontal isometric force in the contralateral (CL), protrusive (P), and ipsilateral (IL) directions and intermediate directions (CL-P, IL-P). In eight subjects, SHLP SMUs were active in CL, CL-P, and P. Qualitatively, SHLP EMG activity increased with increased isometric force. Forty-two SMUs were active in directions other than IL; 6 exhibited activity at IL and other directions. The similarity of these data to previous human lateral Pterygoid (IHLP) data supports the notion that SHLP and IHLP should be regarded as a single Muscle, with activities shaded according to the biomechanical demands of the task.
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Functional properties of single motor units in the inferior head of human lateral Pterygoid Muscle: task firing rates.
Journal of neurophysiology, 2002Co-Authors: I. Phanachet, Terry Whittle, K. Wanigaratne, Greg M MurrayAbstract:The precise function of the inferior head of the human lateral Pterygoid Muscle (IHLP) is unclear. The aim of this study was to clarify the normal function of the IHLP. The hypothesis was that an i...
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Functional properties of single motor units in inferior head of human lateral Pterygoid Muscle: task relations and thresholds.
Journal of neurophysiology, 2001Co-Authors: I. Phanachet, Terry Whittle, K. Wanigaratne, Greg M MurrayAbstract:The aim of this study was to clarify the normal function of the inferior head of the human lateral Pterygoid Muscle (IHLP). The hypothesis was that an important function of the IHLP is in the fine ...
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a method for standardizing jaw displacements in the horizontal plane while recording single motor unit activity in the human lateral Pterygoid Muscle
Journal of Neuroscience Methods, 2001Co-Authors: I. Phanachet, Terry Whittle, K. Wanigaratne, Shinji Uchida, Sheejith Peeceeyen, Greg M MurrayAbstract:Abstract The normal function of the lateral Pterygoid Muscle is not well understood although this Muscle is thought to play an important role in the control of jaw and jaw-joint function and is implicated in temporomandibular disorders (TMD). The lack of a validated method for standardization of jaw movement in studies of lateral Pterygoid function has contributed to the lack of understanding of the normal function of this Muscle. An improved understanding of normal function will allow valid comparisons to be made with TMD patients in order to identify whether purported differences in activity actually exist. This paper describes a methodology for standardizing command jaw movements in the horizontal plane, together with reliable recordings of single-motor-unit (SMU) activity. In six human participants, jaw movements were standardized by having participants track a linear bank of light-emitting diodes (LEDs) aligned on a monitor displaying the mid-incisor point (MIPT). In all participants, the MIPT target (i.e. an illuminated LED) could be tracked, according to a pre-determined criterion, during single- and multiple-step displacements at different rates (1.3–6.5 mm/s at MIPT) and magnitudes (0.65–12 mm) of movement. SMU activity from the superior (SHLP) or inferior (IHLP) head of the lateral Pterygoid Muscle could be reliably discriminated during repeated trials of these defined tasks. This methodology establishes a reliable technique for characterizing the firing properties of SMUs within the lateral Pterygoid, and has implications for analogous studies in other jaw Muscles.
Mamie Mizusaki Iyomasa - One of the best experts on this subject based on the ideXlab platform.
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metabolic and vascular pattern in medial Pterygoid Muscle is altered by chronic stress in an animal model of hypodontia
Physiology & Behavior, 2018Co-Authors: Rodrigo Alberto Restrepo Fernandez, Yamba Carla Lara Pereira, Daniela Mizusaki Iyomasa, Ricardo Alexandre Junqueira Calzzani, Christie Ramos Andrade Leitepanissi, Mamie Mizusaki Iyomasa, Glauce Crivelaro Do NascimentoAbstract:Abstract Psychological stress is an important perpetuating, worsening and risk factor for temporomandibular disorders of muscular or articular origin. Occlusion instability, by the way, is considered a risk factor of this pathology and can be reproduced in some experimental animal models. The exact physiologic mechanism underlying these relations however, remains unclear. Our purpose was to test the hypothesis that chronic stress and unilateral exodontia induce metabolic and vascular changes in the medial Pterygoid Muscle of rats. Adult Wistar rats were submitted to chronic unpredictable stress and/or unilateral exodontia and their plasma and medial Pterygoid Muscle were removed for analysis. The parameters evaluated included plasma levels of corticosterone, metabolic activity by succinate dehydrogenase, oxidative capacity by nicotinamide adenine dinucleotide diaphorase, capillary density by laminin and alfa-CD staining and reactive oxidative species production. Chronic unpredictable stress as an isolated factor, increased oxidative metabolism, capillary density and reactive oxygen species production at medial Pterygoid Muscle. Conversely, exodontia has a main effect in metabolism, promoting glycolytic transformation of Muscle fibers. Association of both factors induced a major glycolytic pattern in Muscle and vascular changes. Our findings provide insights into the mechanisms, possibly inducing metabolic and vascular alterations on medial Pterygoid Muscle of rats, by which chronic stress and occlusal instabilities might be involved as risk factors in the pathophysiology of temporomandibular disorders with muscular components.
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chronic stress effects in contralateral medial Pterygoid Muscle of rats with occlusion alteration
Physiology & Behavior, 2016Co-Authors: Bruno Melo Loyola, Rodrigo Alberto Restrepo Fernandez, Yamba Carla Lara Pereira, Daniela Mizusaki Iyomasa, Christie Ramos Andrade Leitepanissi, Glauce Crivelaro Do Nascimento, João Paulo Mardegan Issa, Mamie Mizusaki IyomasaAbstract:Abstract Temporomandibular disorder (TMD) has a high prevalence in our society, characterized by a severe pain condition of the masticatory Muscles and temporomandibular joint. Despite the indication of multiple factor initiators of TMD, there is still controversy about its etiology and its pathophysiology is poorly understood. Using rats as experimental animals we investigated the effect of unpredictable chronic stress with or without unilateral molar extraction on the contralateral medial Pterygoid Muscle. Our hypothesis is that these two factors induce changes in morphology, oxidative metabolism and oxidative stress of Muscle fibers. Young adult male Wistar rats (± 200 g) were divided into four groups: a group with extraction and unpredictable chronic stress (E + US); with extraction and without stress (E + C); without extraction and with unpredictable chronic stress (NO + US); and a control group without either extraction or stress (NO + C). The animals were subjected to unilateral extraction of the upper left molars, under intraperitoneal anesthesia with 4% Xylazine (10 mg/kg) and 10% Ketamine (80 mg/kg) on day zero. The rats of groups E + US and NO + US were submitted to different protocols of stress, from the 14th day after the extraction. The protocols were different every day for five consecutive days, which were repeated from the 6th day for five days more. Contralateral medial Pterygoid Muscles were obtained on the 24th day after the start of the experiment for morphological, metabolic, capillary density, and oxidative stress analysis. The data from capillary density showed a decrease of capillaries in animals subjected to dental extraction, compared with those without extraction and an increase of laminin expression in the group submitted to the unpredictable chronic stress when compared to the unexposed to stress. SDH test revealed a decrease of light fibers in the group submitted to unilateral extraction of molars, compared with this area in the control group. In E + US and NO + US groups, the deeply stained fibers increased compared to NO + C.·The exodontia factor was able to increase the ROS activity in Muscle, whereas the stress factor does not significantly alter ROS in this tissue. It was concluded that both unpredictable chronic stress and the extraction induce metabolic and density of capillary changes in the contralateral medial Pterygoid Muscle to extraction, suggesting that these factors for a longer period of this experiment could induce Muscle damage related to TMD.
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morphological and histological effects on the medial Pterygoid Muscle after unilateral exodontia in gerbils
Micron, 2008Co-Authors: Mamie Mizusaki Iyomasa, Ana Maria De Oliveira, Fernando De Oliveira, João Paulo Mardegan Issa, Maria Bernadete Sasso Stuani, Iisei WatanabeAbstract:Abstract Morphological effects on the medial Pterygoid Muscle were evaluated in 20 male gerbils (average weight, 55 g) after occlusal alterations induced by extraction of left side molar teeth. Controls were only submitted to surgical stress. Sixty days after surgery, the groups were divided into two subgroups for the following studies: (1) observation of macroscopic morphology and vessels distribution (n = 10); (2) light microscopy histological analysis (n = 10). Group results were statistically compared using the Wilcoxon and Mann–Whitney tests, with a significant value of p
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ultrastructural and biochemical changes of the medial Pterygoid Muscle induced by unilateral exodontia
Micron, 2008Co-Authors: Emmanuel Bazan, Iisei Watanabe, Carlos Alberto Mandarimdelacerda, João Paulo Mardegan Issa, Mamie Mizusaki IyomasaAbstract:Abstract The aim of the present study was to investigate the histological, biochemical and ultrastructural effects of occlusal alteration induced by unilateral exodontia on medial Pterygoid Muscle in guinea pigs, Cavia porcellus. Thirty (n = 30) male guinea pigs (450 g) were divided into two groups: experimental-animals submitted to exodontia of the left upper molars, and sham-operated were used as control. The duration of the experimental period was 60 days. Medial Pterygoid Muscles from ipsilateral and contralateral side were analyzed by histological (n = 10), histochemical (n = 10), and ultrastructural (n = 10) methods. The data were submitted to statistical analysis. When the ipsilateral side was compared to the control group, it showed a significantly shorter neuromuscular spindle length (P 0.05). In the contralateral side, the neuromuscular spindles showed significantly shorter length (P
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ultrastructural and biochemical changes of the medial Pterygoid Muscle induced by unilateral exodontia
Micron, 2008Co-Authors: Emmanuel Bazan, Iisei Watanabe, Carlos Alberto Mandarimdelacerda, João Paulo Mardegan Issa, Elaine Aparecida Del Bel, Mamie Mizusaki IyomasaAbstract:The aim of the present study was to investigate the histological, biochemical and ultrastructural effects of occlusal alteration induced by unilateral exodontia on medial Pterygoid Muscle in guinea pigs, Cavia porcellus. Thirty (n=30) male guinea pigs (450g) were divided into two groups: experimental-animals submitted to exodontia of the left upper molars, and sham-operated were used as control. The duration of the experimental period was 60 days. Medial Pterygoid Muscles from ipsilateral and contralateral side were analyzed by histological (n=10), histochemical (n=10), and ultrastructural (n=10) methods. The data were submitted to statistical analysis. When the ipsilateral side was compared to the control group, it showed a significantly shorter neuromuscular spindle length (P 0.05). In the contralateral side, the neuromuscular spindles showed significantly shorter length (P<0.05), the fibers reflected a higher oxidative capacity, the blood capillaries showed endothelial cell emitting slender sprouting along the pre-existing capillary, and significantly higher blood capillary surface density, and volume density (V(v)=89% Mann-Whitney test, P<0.05). This finding indicated a complex morphological and functional medial Pterygoid Muscle adaptation to occlusal alteration in this experimental model. Considering that neuromuscular spindles are responsible for the control of mandibular positioning and movements, the professional should consider if these changes interfere in the success of clinical procedures in medical field involving stomatognathic structures.
