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Greg M. Murray - One of the best experts on this subject based on the ideXlab platform.
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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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superior head of human Lateral Pterygoid Muscle single motor unit firing rates during isometric force
Archives of Oral Biology, 2007Co-Authors: S Ruangsri, Terry Whittle, Greg M. MurrayAbstract:Abstract The superior head of the human Lateral Pterygoid Muscle (SHLP) has been classically considered to have functions that are independent of the inferior head of the Lateral Pterygoid (IHLP). Recent evidence however suggests that some of the functional properties of the SHLP are similar to those of the IHLP. The aim was to determine whether the functional properties in terms of single motor unit (SMU) firing rates within the SHLP vary with horizontal isometric force (400–800 gwt) and direction (i.e., contraLateral (CL), protrusive (P), ipsiLateral (IL) and intermediate directions, CL-P, IL-P) in a manner similar to those identified for the IHLP, and as would be expected if both SHLP and IHLP should be regarded as one Muscle. In eight subjects, the firing rates of 40 SMUs were recorded from computer tomography (CT)-verified SHLP sites while each subject exerted horizontal isometric forces with their lower jaw onto a force transducer in the five directions. Firing rates increased significantly with horizontal isometric force from 400 to 800 gwt. Firing rates also changed significantly ( p
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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, Christopher C. Peck, I. Phanachet, Terry Whittle, 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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functional activity of superior head of human Lateral Pterygoid Muscle during isometric force
Journal of Dental Research, 2005Co-Authors: S Ruangsri, K. Wanigaratne, Terry Whittle, 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.
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, Christopher C. Peck, I. Phanachet, Terry Whittle, 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 ...
Li Li Min - One of the best experts on this subject based on the ideXlab platform.
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Lateral Pterygoid Muscle volume and migraine in patients with temporomandibular disorders
Imaging Science in Dentistry, 2015Co-Authors: Sérgio Lúcio Pereira De Castro Lopes, André Luiz Ferreira Costa, Thiago De Oliveira Gamba, Isadora Luana Flores, Adriana Dibo Da Cruz, Li Li MinAbstract:Purpose: Lateral Pterygoid Muscle (LPM) plays an important role in jaw movement and has been implicated in Temporomandibular disorders (TMDs). Migraine has been described as a common symptom in patients with TMDs and may be related to Muscle hyperactivity. This study aimed to compare LPM volume in individuals with and without migraine, using segmentation of the LPM in magnetic resonance (MR) imaging of the TMJ. Materials and Methods: Twenty patients with migraine and 20 volunteers without migraine underwent a clinical examination of the TMJ, according to the Research Diagnostic Criteria for TMDs. MR imaging was performed and the LPM was segmented using the ITK-SNAP 1.4.1 software, which calculates the volume of each segmented structure in voxels per cubic millimeter. The chi-squared test and the Fisher’s exact test were used to relate the TMD variables obtained from the MR images and clinical examinations to the presence of migraine. Logistic binary regression was used to determine the importance of each factor for predicting the presence of a migraine headache. Results: Patients with TMDs and migraine tended to have hypertrophy of the LPM (58.7%). In addition, abnormal mandibular movements (61.2%) and disc displacement (70.0%) were found to be the most common signs in patients with TMDs and migraine. Conclusion: In patients with TMDs and simultaneous migraine, the LPM tends to be hypertrophic. LPM segmentation on MR imaging may be an alternative method to study this Muscle in such patients because the hypertrophic LPM is not always palpable. (Imaging Sci Dent 2015; 45: 1-5)
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Lateral Pterygoid Muscle volume and migraine in patients with temporomandibular disorders
Imaging Science In Dentistry, 2015Co-Authors: Lopes, Sérgio Lúcio Pereira De Castro [unesp], Costa, André Luiz Ferreira, Gamba, Thiago De Oliveira, Flores, Isadora Luana, Cruz, Adriana Dibo, Li Li MinAbstract:Lateral Pterygoid Muscle (LPM) plays an important role in jaw movement and has been implicated in Temporomandibular disorders (TMDs). Migraine has been described as a common symptom in patients with TMDs and may be related to Muscle hyperactivity. This study aimed to compare LPM volume in individuals with and without migraine, using segmentation of the LPM in magnetic resonance (MR) imaging of the TMJ. Twenty patients with migraine and 20 volunteers without migraine underwent a clinical examination of the TMJ, according to the Research Diagnostic Criteria for TMDs. MR imaging was performed and the LPM was segmented using the ITK-SNAP 1.4.1 software, which calculates the volume of each segmented structure in voxels per cubic millimeter. The chi-squared test and the Fisher's exact test were used to relate the TMD variables obtained from the MR images and clinical examinations to the presence of migraine. Logistic binary regression was used to determine the importance of each factor for predicting the presence of a migraine headache. Patients with TMDs and migraine tended to have hypertrophy of the LPM (58.7%). In addition, abnormal mandibular movements (61.2%) and disc displacement (70.0%) were found to be the most common signs in patients with TMDs and migraine. In patients with TMDs and simultaneous migraine, the LPM tends to be hypertrophic. LPM segmentation on MR imaging may be an alternative method to study this Muscle in such patients because the hypertrophic LPM is not always palpable
Terry Whittle - One of the best experts on this subject based on the ideXlab platform.
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superior head of human Lateral Pterygoid Muscle single motor unit firing rates during isometric force
Archives of Oral Biology, 2007Co-Authors: S Ruangsri, Terry Whittle, Greg M. MurrayAbstract:Abstract The superior head of the human Lateral Pterygoid Muscle (SHLP) has been classically considered to have functions that are independent of the inferior head of the Lateral Pterygoid (IHLP). Recent evidence however suggests that some of the functional properties of the SHLP are similar to those of the IHLP. The aim was to determine whether the functional properties in terms of single motor unit (SMU) firing rates within the SHLP vary with horizontal isometric force (400–800 gwt) and direction (i.e., contraLateral (CL), protrusive (P), ipsiLateral (IL) and intermediate directions, CL-P, IL-P) in a manner similar to those identified for the IHLP, and as would be expected if both SHLP and IHLP should be regarded as one Muscle. In eight subjects, the firing rates of 40 SMUs were recorded from computer tomography (CT)-verified SHLP sites while each subject exerted horizontal isometric forces with their lower jaw onto a force transducer in the five directions. Firing rates increased significantly with horizontal isometric force from 400 to 800 gwt. Firing rates also changed significantly ( p
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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, Christopher C. Peck, I. Phanachet, Terry Whittle, 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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functional activity of superior head of human Lateral Pterygoid Muscle during isometric force
Journal of Dental Research, 2005Co-Authors: S Ruangsri, K. Wanigaratne, Terry Whittle, 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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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.
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, Christopher C. Peck, I. Phanachet, Terry Whittle, 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, K. Wanigaratne, Terry Whittle, 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.
