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Nozad Mojaver Y, Tawadros P, Moura Ferreira P, Whittle T, Murray GM. Threshold variations of medial pterygoid single motor units during vertical or horizontal force tasks. J Oral Rehabil 2021; 48:1314-1326. [PMID: 34510487 DOI: 10.1111/joor.13257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 08/19/2021] [Accepted: 09/01/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To test the hypotheses that (a) the force thresholds at onset of medial pterygoid muscle single motor unit (SMU) activity do not decrease with an increase in the rate of force generation in standardised vertical or horizontal jaw-force tasks, and (b) there is evidence for functional heterogeneity within the medial pterygoid muscle. METHODS In 14 healthy participants, electromyographic recordings of the right medial pterygoid muscle were performed with intramuscular fine-wire electrodes during four isometric force tasks: vertical, horizontal contralateral, horizontal protrusion and horizontal ipsilateral, performed at two rates of force development (slow ramp, fast ramp). Computer tomography scans confirmed electrode location within the muscle, which was divided into medial and lateral parts. Force thresholds of onset of discriminated SMUs were compared between rates in each task; significance accepted at p < 0.05. RESULTS Of 45 SMU force thresholds studied in one or more tasks, there was no significant difference between slow and fast ramp within each force task, except slow ramp thresholds from the lateral part during the vertical force task were significantly higher than fast ramp thresholds. Reversals of recruitment order between tasks provided evidence for functional heterogeneity within the muscle. Force thresholds of the vertical tasks (range: 1-292.6 N) were mostly higher than for the horizontal tasks (range: 0.1-12.5 N). CONCLUSION The data are consistent with the proposal that the medial pterygoid muscle stabilises the jaw in the vertical plane during isometric force generation in the jaw closing, as well as horizontal directions.
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Affiliation(s)
- Yalda Nozad Mojaver
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
| | - Paul Tawadros
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
| | - Polyana Moura Ferreira
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
| | - Terry Whittle
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
| | - Greg M Murray
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
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Plasticity in corticomotor pathways linked to a jaw protrusion training task: Potential implications for management of patients with obstructive sleep apnea. Brain Res 2020; 1749:147124. [DOI: 10.1016/j.brainres.2020.147124] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 08/20/2020] [Accepted: 09/08/2020] [Indexed: 12/13/2022]
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Chen H, Whittle T, Gal J, Klineberg IJ, Murray GM. Functional properties of single motor units in the human medial pterygoid muscle: Thresholds. J Oral Rehabil 2020; 48:132-142. [PMID: 33068481 DOI: 10.1111/joor.13115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 10/01/2020] [Accepted: 10/06/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND Little is known regarding the functional properties of single motor units (SMUs) in the medial pterygoid muscle (MPt) during jaw movements. OBJECTIVES The aims are (a) to report the thresholds of onset of MPt SMUs during 4 goal-directed jaw movement tasks, and (b) to determine whether the threshold of onset of SMU activation varies with the velocity of jaw movement and the location within the muscle. METHODS Intra-muscular electrodes were inserted in the right MPt of 18 participants performing ipsilateral (right), contralateral, protrusive and opening-closing jaw movements recorded at 2 velocities. Task phases were as follows: BEFORE, OUT, HOLDING, RETURN and AFTER. SMU onset thresholds were determined from the displacement (mm) of the lower mid-incisor point. Electrode location within 4 arbitrary muscle divisions was determined with computer tomography. Statistical tests: Spearman's correlations, Kruskal-Wallis tests; significance accepted at P < .05. RESULTS A significant inverse relation occurred between velocity and threshold for the RETURN of the ipsilateral movement (n = 62 SMU thresholds), while a significant positive relation occurred for the OUT of the contralateral movement (n = 208); there were no significant associations for the protrusive (n = 131) and opening-closing (n = 58) tasks. Significant threshold differences occurred across the 4 muscle divisions only during the OUT of the contralateral and protrusive movements. Some evidence was provided for gender differences in MPt SMU properties. CONCLUSIONS The absence of a significant inverse relation between velocity and SMU threshold for most recorded movements suggests the MPt acts as a stabilizer of the jaw in horizontal and opening-closing jaw movements.
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Affiliation(s)
- Hui Chen
- Jaw Function and Orofacial Pain Research Unit, Faculty of Medicine and Health, Sydney Dental School, Level 2, Westmead Hospital Centre for Oral Health, University of Sydney, Sydney, NSW, Australia
| | - Terry Whittle
- Jaw Function and Orofacial Pain Research Unit, Faculty of Medicine and Health, Sydney Dental School, Level 2, Westmead Hospital Centre for Oral Health, University of Sydney, Sydney, NSW, Australia
| | - John Gal
- Jaw Function and Orofacial Pain Research Unit, Faculty of Medicine and Health, Sydney Dental School, Level 2, Westmead Hospital Centre for Oral Health, University of Sydney, Sydney, NSW, Australia
| | - Iven J Klineberg
- Jaw Function and Orofacial Pain Research Unit, Faculty of Medicine and Health, Sydney Dental School, Level 2, Westmead Hospital Centre for Oral Health, University of Sydney, Sydney, NSW, Australia
| | - Greg M Murray
- Jaw Function and Orofacial Pain Research Unit, Faculty of Medicine and Health, Sydney Dental School, Level 2, Westmead Hospital Centre for Oral Health, University of Sydney, Sydney, NSW, Australia
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Hudson AL, Gandevia SC, Butler JE. A Principle of Neuromechanical Matching for Motor Unit Recruitment in Human Movement. Exerc Sport Sci Rev 2019; 47:157-168. [DOI: 10.1249/jes.0000000000000191] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Yamaguchi S, Okada C, Watanabe Y, Watanabe M, Hattori Y. Analysis of masticatory muscle coordination during unilateral single-tooth clenching using muscle functional magnetic resonance imaging. J Oral Rehabil 2017; 45:9-16. [PMID: 29090477 DOI: 10.1111/joor.12583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2017] [Indexed: 12/15/2022]
Abstract
In a previous study, we used muscle functional magnetic resonance imaging to show that the anterior movement of the occlusal point increased the activity of the superior head of the ipsilateral lateral pterygoid muscle (ipsilateral SHLP) during unilateral single-tooth clenching. The purpose of this study was to verify the hypothesis that the increased activity of the ipsilateral SHLP described above serves to antagonise the occlusal force acting on the condyle. In total, 9 healthy volunteers were requested to perform left unilateral clenching at the first molar or first premolar region for 1 minute at 20% or 40% maximum voluntary clenching force. Changes in the mean proton transverse relaxation time (∆T2) were examined from the magnetic resonance images obtained before and after each clenching act as an index of the activity in all masticatory muscles. Correlation analyses of the mean ΔT2 for each volume of interest were performed with the first molar or premolar clenches to analyse the correlation between the activities in each muscle. A statistically significant correlation was exhibited between the ipsilateral temporal and ipsilateral SHLP (r = .651, P = .003) during first premolar clenching. However, no significant correlations were observed in the ipsilateral SHLP during first molar clenching. The results of this study suggest that the ipsilateral SHLP may contribute to the pulling of the mandibular condyle forward against the occlusal force generated by the ipsilateral temporal muscle.
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Affiliation(s)
- S Yamaguchi
- Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - C Okada
- Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Y Watanabe
- Department of Health Services Management, Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Japan.,Kansei Fukushi Research Center, Tohoku Fukushi University, Sendai, Japan
| | - M Watanabe
- Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan.,Kansei Fukushi Research Center, Tohoku Fukushi University, Sendai, Japan
| | - Y Hattori
- Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
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Litko M, Szkutnik J, Berger M, Różyło-Kalinowska I. Correlation between the lateral pterygoid muscle attachment type and temporomandibular joint disc position in magnetic resonance imaging. Dentomaxillofac Radiol 2016; 45:20160229. [PMID: 27506381 DOI: 10.1259/dmfr.20160229] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The aim of this study was to investigate the correlation between the lateral pterygoid muscle (LPM) attachment type and temporomandibular joint (TMJ) disc position on sagittal and coronal MR scans. METHODS 191 patients (148 females, 43 males), aged 14-60 years, underwent MR investigations of the TMJs in the intercuspal position (IP) and open-mouth position (OMP). The disc position was evaluated on oblique sagittal and coronal images in the IP and OMP on many MRI sections showing all portions of the joint. Relationships between the LPM attachment patterns and articular disc positions were evaluated by z and χ2 tests. RESULTS Three types of the LPM attachment were found. There was a statistically significant correlation between the LPM attachment type and the disc position in IP (χ2 = 24.29; p < 0.01). The type of muscle attachment did not determine the prevalence of normal, lateral and medial disc positions. There were differences between the muscle attachment types in the anterior, anteromedial and anterolateral disc positions. There was a statistically significant association between TMJ disc position in OMP and particular attachment types in the sagittal plane (χ2 = 9.702; p < 0.01). CONCLUSIONS Certain types of the LPM insertion are correlated with TMJ disc position.
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Affiliation(s)
- Monika Litko
- 1 Department of Functional Masticatory Disorders, Medical University of Lublin, Lublin, Poland
| | - Jacek Szkutnik
- 1 Department of Functional Masticatory Disorders, Medical University of Lublin, Lublin, Poland
| | - Marcin Berger
- 1 Department of Functional Masticatory Disorders, Medical University of Lublin, Lublin, Poland
| | - Ingrid Różyło-Kalinowska
- 2 Independent Unit of Propedeutics of Dentomaxillofacial Radiology, Medical University of Lublin, Lublin, Poland
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Antonopoulou M, Iatrou I, Paraschos A, Anagnostopoulou S. Variations of the attachment of the superior head of human lateral pterygoid muscle. J Craniomaxillofac Surg 2012; 41:e91-7. [PMID: 23265808 DOI: 10.1016/j.jcms.2012.11.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 11/09/2012] [Accepted: 11/12/2012] [Indexed: 10/27/2022] Open
Abstract
INTRODUCTION The superior head of the lateral pterygoid muscle (LPM), is closely related to the temporomandibular joint (TMJ) and plays a role in the aetiology of temporomandibular disorders. Increased activity of this muscle has been implicated in the anterior displacement of the TMJ disc. However, there is uncertainty about the manner of the LPM attachment to the disc-condyle complex. AIM The aim of this study was to investigate the exact anatomy of the attachment of the superior head of the LPM (SLPM) to the disc-condyle complex of the TMJ. MATERIAL AND METHODS Thirty-six TMJs were examined - both sides of 18 Greek cadavers (eight males and 10 females, mean age 79.6 years). Examination of the attachment of the SLPM was undertaken viewed under the dissecting microscope. RESULTS Variation in the attachment of the SLPM was categorized into three types: in type I, the SLPM inserted into the condyle and the disc-capsule complex (55.5%). In type II, the SLPM only inserted into the condyle (27.8%). In type III, the SLPM inserted purely into the disc-capsule complex (16.7%). CONCLUSIONS This study demonstrates that there are three different attachment types of the SLPM to the disc-condyle complex. The type III variation could be involved in the TMJ pathology. The knowledge of the variations of the SLPM attachment could be useful for precise surgical and pharmaceutical approaches.
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Davies J, Charles M, Cantelmi D, Liebgott B, Ravichandiran M, Ravichandiran K, Agur A. Lateral pterygoid muscle: A three-dimensional analysis of neuromuscular partitioning. Clin Anat 2011; 25:576-83. [DOI: 10.1002/ca.21298] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2011] [Revised: 09/22/2011] [Accepted: 10/11/2011] [Indexed: 11/11/2022]
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Hudson AL, Gandevia SC, Butler JE. Control of human inspiratory motoneurones during voluntary and involuntary contractions. Respir Physiol Neurobiol 2011; 179:23-33. [DOI: 10.1016/j.resp.2011.06.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 06/14/2011] [Accepted: 06/14/2011] [Indexed: 11/17/2022]
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