Copies of author's previously published articles inserted. / Bibliography: leaves 172-204. / xi, 211 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / H-relexes are used to determine the reflex connections of muscle spindle afferents, the exitability of the motorneuron pool and the integrity of the reflex pathways. However, H-relexes are small and can be difficult to elicit in the masseter, limiting their use in the investigation of the masticatory system. This study investigated the recruitment of masseter motorneurons into the H-reflex, compared to the recruitment occuring during voluntary isometric biting, to determine the distribution of the effective muscle spindle input. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physiology, 1999

Thesis (Ph. D.)--University of Adelaide, 1989. / Typescript (Photocopy). Copy of published paper co-authored by author, in back. Includes bibliographical references (leaves 209-228).

There is a dearth of knowledge on the functional organization of the anatomically complex human masseter muscle. Limited physiological studies suggest a functional organization which may differ significantly from human limb muscles. The present studies aimed to examine the putative relationship between structure and function in the human masseter muscle as a basis for understanding function and dysfunction in human jaw muscles. In the first experiment single motor unit (SMU) activity was recorded from pairs of recording sites distributed throughout the masseter muscle. In each case SMU activity at a chosen location was used as a reference to search for synchronized SMU activity at another selected site. The locations of the needle tips were estimated in 3-dimensions (3-D) by means of an optical system, then transferred to 3-D reconstructions derived from Magnetic Resonance images. This approach permitted calculation of the linear distances between verified muscle recording sites. The mean separation of the sites from which synchronous SMU activity could be recorded was 8.8±3.4mm. The putative territories had a preferred orientation in the antero-posterior axis. Motor unit territories were larger than described previously, and appeared to be related to anatomical compartments. The second experiment involved recording activity from stereotactically mapped masseter SMUs. In each case, the lowest sustainable firing frequency (LSFF) was reached by slow increases and decreases in voluntary firing rate, followed by sustained firing at the lowest possible rate. Pulse-discrimination and digital sampling of consecutive inter-spike intervals (ISIs) were then used to measure LSFF for 2-6 separate occlusal and postural tasks to which each unit contributed. There were significant differences between mean ISIs for the tasks performed by most units, which suggests descending drive to masseter units is highly task-dependent. There were also regional differences in unit task specificities. In the third paradigm, reflex SMU activity was recorded from units in the masseter muscle and the inferior head of the lateral pterygoid muscle. Bipolar electrodes fixed to the gingiva near the maxillary canine delivered single pulses of 1ms duration at sub-noxious levels of intensity. At constrained firing frequencies (10, 15Hz), pulses were injected sequentially, with increasing delays, after preselected spikes. More profound inhibition occurred in units firing at 10 than 15Hz. There were significant differences in masseter inhibitory responses when the unit task varied. Reflex inhibition in masseter and lateral pterygoid SMUs is highly frequency-dependent, and also task-dependent in masseter units. The fourth study involved recording activity from SMUs in the masseter muscle. A midline load cell was fixed to the incisor teeth and aligned either perpendicular (P) or 30 degrees anterior (A) to the occlusal plane, without altering jaw position. A rigid spike-triggered averaging (STA) paradigm was used to extract the contribution of individual SMUs to the overall force at load cell orientations P and A. Spikes preceded or followed by an interval of less than 100ms were rejected prior to averaging. At background bite forces from 0.06-8N, the isometric forces apparently developed by individual units varied randomly with load cell orientations, (P range 36.2±19.6mN; A range 38.2±28.4mN). All units could be fired slowly with varying degrees of muscle coactivation, in some instances without contact on the load cell. The use of STA as a method for determining SMU tension in the masseter muscle appears to be task-dependent and in the presence of coactivation may be inappropriate. The findings collectively indicate the heterogeneous nature of SMU behaviour in the human masseter muscle which is consistent with internal muscle compartments based on anatomical features and functional behaviour. There thus appear to be both physiological and anatomical substrates for differential motor control of selected regions of the human masseter muscle. / Dentistry, Faculty of / Graduate

Headache is a common complaint in society and is related to personal, biomechanical and socioeconomic circumstances. In current literature trigger-points (TrPs) in the majority of the muscles of the face and neck contributing to tension-type headache (TTH) have been evaluated, except the TrPs of the masseter muscles. The aim of this studyis to determine the association between myofascial (TrPs) in the masseter muscle group and episodic tension-type headache (ETTH). Fourteen subjects with ETTH were matched with same sex and same age subjects not suffering from headache acting as the control group. The diagnostic criteria as described by Simons and Travel (1999) were used in the objective tests to diagnose the TrPs in the masseter muscles. Subjective tests included a disability questionnaire, National stress awareness day stress questionnaire, (NSAD stress questionnaire), a precipitating and aggravating factors questionnaire. Active TrPs were found in 92.86% of ETTH group and 7.14% had latent TrPs. Within the control group 7.14% had active TrPs, 14.29% latent TrPs and 78.37% had no TrPs.Differences in the presence of masseter TrPs between the ETTH and control group were significant with p-value <0.001. All the questions asked in the headache disability questionnaire evaluating headache frequency, intensity and severity were significantwith p-value<0.005. The NSAD stress questionnaire revealed statistical significant values for questions pertaining to muscular aches and pains and subjectively subjects claimed that theyfelt tension at work. The precipitating questionnaire showed that physical activity, stress / tension and reading were significant precipitating factors for developing a tension-type headache. The aggravating questionnaire only showed light as an aggravating factor. Stress and tension had 100% “yes”answers in the ETTH group.Weather as an aggravating factor had 100% “no” answersfrom the control group.Physical activity, driving and noise had relative high percentages of “yes”answers from the ETTH group and higher probability scores for being an aggravating factor whencomparing the ETTH and control group, but were not found to be statistically significant. Myofascial TrPs in the masseter muscle group contribute to the origin and or maintenance of ETTH.

Embriologicamente, o tecido ósseo surge posteriormente aos músculos. A musculatura temporomandibular e facial apresentam-se definidas quando da ossificação da face e crânio, com os ossos se desenvolvendo dentro de um envelope de músculo e fascia. Quando contrações ativas se iniciam em um músculo, ele passa a exercer contínuo efeito sobre os ossos aos quais pertencem sua origem e inserção. O tecido ósseo é tido como um dos mais plásticos e responde prontamente às forças e tensões geradas pelos músculos. Evidenciase que os músculos, desde a fase pré-natal, desempenham papel na conformação dos ossos, e continuam a direcionar o crescimento pelo efeito de suas funções. Oito pacientes (4? e 4?) com idade entre 7 e 12 anos, com maloclusão dental classe III de Angle, foram submetidos a registros eletromiográficos do músculo masseter, subdividido em três regiões: superior, média e inferior, empregando-se o eletromiógrafo K6-I/EMG Eight Channel Surface Electromyograph (Myo-tronics Co., Seatle, WA, EUA), em 17 condições clínicas, e à análise cefalométrica através do programa Radiocef (RadioMemory, Floresta, BH, Brasil), de 15 medidas angulares e lineares. Os dados obtidos foram submetidos ao teste de correlação de Spearman, por meio do programa Statistica, release 4.3D (StatSoft, Inc., 1993, EUA). Correlações estatisticamente significantes foram encontradas entre as condições clínicas de repouso, propulsão livre da mandíbula, mastigação molar, oclusão cêntrica forçada, desvio lateral, deglutição de água, mastigação incisiva, fechamento contra-resistência e deglutição de saliva; e, entre as medidas cefalométricas, ângulo SNA, ângulo incisivo superior.NA, distância incisivo superior-NA, ângulo ANB, ângulo IMPA, distância Pog-NB, ângulo SN.Gn(Y), ângulo incisivo inferior.NB, ângulo interincisivo, distância incisivo inferior-NB, ângulo SN.GoGn, ângulo SN.Plano Oclusal, ângulo SNB e ângulo SND. As regiões superior, média e inferior do músculo masseter participaram em 32, 18 e 50% dos resultados estatisticamente significantes, respectivamente. Os resultados corroboram com hipóteses sobre a influência da musculatura no estabelecimento da maloclusão dental, e a relação entre a função dos músculos do sistema estomatognático e o desenvolvimento craniofacial precisa ser compreendida para se poder predizer o desenvolvimento craniofacial. / Embryologically, the bone tissue develops after muscle tissue. The temporomandibular and facial muscles are well defined when the cranial and facial ossifications occur, with bone structures developing inside of a muscle and fascia envelope. When active contractions begin in a muscle, it exerts an uninterrupted effect over bones to which belongs its origin and insertion. The bones tissues are one of the most plastic tissues, and interact readily to any tension and pressure developed by muscles. It\'s axiomatic that since previous to childbirth, muscles exert a role in bone structure development, and keep directing the skeletal growth with the effect of its functions. Eight patients (4? and 4?), between 7 and 12 years of age, with Angle\'s class III dental malocclusion were studied using electromyographic registers of the masseter muscle, divided in three regions: superior, middle and inferior, and cephalometric analysis. The K6-I/EMG Eight Channel Surface Electromyograph (Myo-tronics Co., Seatle, WA, EUA) was employed to get the registers in 17 clinical conditions, and the Radiocef (RadioMemory, Floresta, BH, Brasil) software was employed to get cephalometric analysis of 15 linear and angular measurements. The data obtained were submitted to statistical analysis by Spearman correlation test, with the Statistica, release 4.3D (StatSoft, Inc., 1993, EUA) software. Correlations were found among the clinical conditions of rest, free protraction of the jaw, molar chewing, centric occlusion, lateral movement without occlusal contact, swallowing water, incisal chewing, clenching the jaw against resistance and swallowing saliva; and among the following cephalometric measurements: the SNA angle, the Upper Incisor.NA angle, Upper Incisor-NA distance, ANB angle, IMPA angle, Pog-NB distance, SN.Gn(Y) angle, Lower Incisor.NB angle, Interincisors angle, Lower Incisor-NB distance, SN.GoGn angle, SN.Occlusal Plane angle, SNB angle and SND angle. The superior, middle and inferior regions of the masseter muscle were present in 32, 18 and 50% of the statistically significant results, respectively. The results reinforce the assumption of muscle influence over the development of dental malocclusion, and that the interaction of muscle function and skeletal growth must be understood to predict craniofacial development.

Thesis (M.S.)--University of Michigan, 1985.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains viii, 88 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 62-66).

Embriologicamente, o tecido ósseo surge posteriormente aos músculos. A musculatura temporomandibular e facial apresentam-se definidas quando da ossificação da face e crânio, com os ossos se desenvolvendo dentro de um envelope de músculo e fascia. Quando contrações ativas se iniciam em um músculo, ele passa a exercer contínuo efeito sobre os ossos aos quais pertencem sua origem e inserção. O tecido ósseo é tido como um dos mais plásticos e responde prontamente às forças e tensões geradas pelos músculos. Evidenciase que os músculos, desde a fase pré-natal, desempenham papel na conformação dos ossos, e continuam a direcionar o crescimento pelo efeito de suas funções. Oito pacientes (4? e 4?) com idade entre 7 e 12 anos, com maloclusão dental classe III de Angle, foram submetidos a registros eletromiográficos do músculo masseter, subdividido em três regiões: superior, média e inferior, empregando-se o eletromiógrafo K6-I/EMG Eight Channel Surface Electromyograph (Myo-tronics Co., Seatle, WA, EUA), em 17 condições clínicas, e à análise cefalométrica através do programa Radiocef (RadioMemory, Floresta, BH, Brasil), de 15 medidas angulares e lineares. Os dados obtidos foram submetidos ao teste de correlação de Spearman, por meio do programa Statistica, release 4.3D (StatSoft, Inc., 1993, EUA). Correlações estatisticamente significantes foram encontradas entre as condições clínicas de repouso, propulsão livre da mandíbula, mastigação molar, oclusão cêntrica forçada, desvio lateral, deglutição de água, mastigação incisiva, fechamento contra-resistência e deglutição de saliva; e, entre as medidas cefalométricas, ângulo SNA, ângulo incisivo superior.NA, distância incisivo superior-NA, ângulo ANB, ângulo IMPA, distância Pog-NB, ângulo SN.Gn(Y), ângulo incisivo inferior.NB, ângulo interincisivo, distância incisivo inferior-NB, ângulo SN.GoGn, ângulo SN.Plano Oclusal, ângulo SNB e ângulo SND. As regiões superior, média e inferior do músculo masseter participaram em 32, 18 e 50% dos resultados estatisticamente significantes, respectivamente. Os resultados corroboram com hipóteses sobre a influência da musculatura no estabelecimento da maloclusão dental, e a relação entre a função dos músculos do sistema estomatognático e o desenvolvimento craniofacial precisa ser compreendida para se poder predizer o desenvolvimento craniofacial. / Embryologically, the bone tissue develops after muscle tissue. The temporomandibular and facial muscles are well defined when the cranial and facial ossifications occur, with bone structures developing inside of a muscle and fascia envelope. When active contractions begin in a muscle, it exerts an uninterrupted effect over bones to which belongs its origin and insertion. The bones tissues are one of the most plastic tissues, and interact readily to any tension and pressure developed by muscles. It\'s axiomatic that since previous to childbirth, muscles exert a role in bone structure development, and keep directing the skeletal growth with the effect of its functions. Eight patients (4? and 4?), between 7 and 12 years of age, with Angle\'s class III dental malocclusion were studied using electromyographic registers of the masseter muscle, divided in three regions: superior, middle and inferior, and cephalometric analysis. The K6-I/EMG Eight Channel Surface Electromyograph (Myo-tronics Co., Seatle, WA, EUA) was employed to get the registers in 17 clinical conditions, and the Radiocef (RadioMemory, Floresta, BH, Brasil) software was employed to get cephalometric analysis of 15 linear and angular measurements. The data obtained were submitted to statistical analysis by Spearman correlation test, with the Statistica, release 4.3D (StatSoft, Inc., 1993, EUA) software. Correlations were found among the clinical conditions of rest, free protraction of the jaw, molar chewing, centric occlusion, lateral movement without occlusal contact, swallowing water, incisal chewing, clenching the jaw against resistance and swallowing saliva; and among the following cephalometric measurements: the SNA angle, the Upper Incisor.NA angle, Upper Incisor-NA distance, ANB angle, IMPA angle, Pog-NB distance, SN.Gn(Y) angle, Lower Incisor.NB angle, Interincisors angle, Lower Incisor-NB distance, SN.GoGn angle, SN.Occlusal Plane angle, SNB angle and SND angle. The superior, middle and inferior regions of the masseter muscle were present in 32, 18 and 50% of the statistically significant results, respectively. The results reinforce the assumption of muscle influence over the development of dental malocclusion, and that the interaction of muscle function and skeletal growth must be understood to predict craniofacial development.

Orientador: Fausto Berzin / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-12T18:58:58Z (GMT). No. of bitstreams: 1 Borini_CyntiaBicalho_D.pdf: 684876 bytes, checksum: 0aec71096f81bf77bf3f9165ae00a545 (MD5) Previous issue date: 2008 / Resumo: O objetivo deste trabalho foi avaliar a variabilidade interdias e intradias dos valores dos registros eletromiográficos, da parte superficial do músculo masseter e parte anterior do músculo temporal e a relação destes registros com o fator emocional, ansiedade, em três dias distintos de coleta. Foram selecionadas 16 voluntárias livres da presença de sinais e sintomas de disfunção temporomandibular, diagnosticadas de acordo com o Critério de Diagnóstico para Pesquisa das Disfunções Tmporomandibulares (RDC/TMD). Medidas cefalométricas em telerradiografias em norma lateral foram utilizadas para classificá-los de acordo com a relação de bases ósseas maxilo-mandibular em Classe I e II e com relação às dimensões verticais da face em tipo facial distinto, mesofacial e dolicofacial. Para a mensuração da ansiedade, foi utilizado o Inventário de Ansiedade Traço-Estado (IDATE). O exame eletromiográfico foi realizado utilizando o eletromiógrafo Myosystem Br1â de 12 canais, com 12 bites de resolução e ganho de até 50 vezes, freqüência de amostragem de 4.000 Hz, com eletrodos bipolares passivos acoplados a um pré-amplificador com ganho fixo de 20 vezes. Durante este foram realizadas as atividades de mastigação bilateral simultânea, mastigação habitual e contração voluntária em máxima intercuspidação em três dias distintos com intervalo de uma semana entre eles e três repetições em cada dia. Os sinais eletromiográficos foram processados, normalizados e em seguida, foram calculadas as variáveis instante máximo (Imax) e tempo de ativação (ON) para a análise da atividade elétrica dos músculos avaliados durante as tarefas por uma rotina do software Matlab versão 5.3. Como resultado, houve uma variabilidade entre a comparação das médias da variável ON da parte superficial do músculo masseter direito na atividade de mastigação habitual em diferentes dias de coleta (p=0,02). Durante a mastigação bilateral simultânea houve uma variabilidade entre a comparação das médias da variável ON da parte anterior do músculo temporal direito nas diversas repetições (p=0,03). Dada a variabilidade apresentada por estes músculos, existe a necessidade de se avaliar os registros eletromiográficos tanto na mastigação habitual quanto na mastigação bilateral simultânea da parte superficial do músculo masseter e parte anterior do músculo temporal em mais de uma sessão e mais de uma repetição no mesmo dia. Em relação à ansiedade, os resultados mostraram uma associação inversa entre a variável tempo de ativação e os níveis de ansiedade-traço durante as duas atividades e uma associação direta entre a variável instante máximo e os níveis de ansiedade-traço durantes as duas atividades. Apenas a parte anterior do músculo temporal apresentou, durante a mastigação habitual, uma relação direta entre a variável instante máximo com a ansiedade-estado e, durante a mastigação bilateral simultânea, a variável tempo de ativação foi que mostrou uma relação inversa para o mesmo músculo. Conclui-se que a ansiedade-traço e estado podem influenciar em registros eletromiográficos mesmo em situações não experimentais. / Abstract: The aim of this study was to evaluate the interday and intraday variability in the values of electromyographic recordings of the superficial part of the masseter muscle and anterior part of the temporal muscle. Besides, it also purposed to verify the relationship of these recordings with the emotional factors, anxiety, at three different days of data collection. Sixteen volunteers, free of signs and symptoms of temporomandibular desorder, according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were selected. Cephalometric measurements in lateral teleradiographs were used to classify the subjects into Class I and II, according to the relationship of maxillo-mandibular bone bases and regarding considering the vertical dimensions of the face into distinct mesofacial and dolicofacial types. To measure anxiety, the State-Trait Anxiety Inventory (STAI) was used. The electromyographic exam was carried out with Myosystem Br 1â electromyograph of 12 channels, with a resolution of 12 bites and gain up to 50 times, sampling frequency of 4000 Hz, bipolar passive electrodes coupled to a pre-amplifier with 20 times gain. The tasks of simultaneous bilateral chewing, habitual chewing and voluntary contraction in maximum intercuspidation were performed, at three different days, with interval of one week among them, and three repetitions on each day. The electromyographic signals were processed and normalized, and then the electrical activity of assessed muscles during the tasks were calculated through the instant maximum (Imax) and the time of activation (ON) the software Matlab version 5.3. As results, there was a variability between the comparison of the average of variable ON of the right masseter muscle in the habitual chewing on the various days of collection (p=0.02). While evaluating simultaneous bilateral chewing variability between the comparison of the average of variable ON of the anterior part of the right temporal muscle in the various repetitions (p=0.03). Given the variability shown by these muscles, there is a need to evaluate the electromyographic records both in habitual chewing and in the simultaneous bilateral chewing of these muscles in more than one session and more than one repetition. Regarding to anxiety, the results showed a reverse association between the variable activation time and the levels of trait-anxiety during the two tasks, and a direct association between the variable Imax and the levels of trait-anxiety during the two tasks. Only the anterior part of the temporal muscle during habitual chewing presented a direct relationship between the variable Imax and state-anxiety; and during simultaneous bilateral chewing the variable ON showed a reverse relationship for the same muscle. Thus it was concluded that the trait and state anxiety can influence electromyographic records, even in non-experimental situations. / Doutorado / Anatomia / Doutor em Biologia Buco-Dental

Orientador: Alfio Jose Tincani / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-08T00:52:46Z (GMT). No. of bitstreams: 1 Servin_SilvioOscarNoguera_M.pdf: 2672274 bytes, checksum: d28fc71e2ce565530de5649e1baaa489 (MD5) Previous issue date: 2006 / Resumo: A hipertrofia massetérica (HM) caracteriza-se pelo aumento do músculo masseter de origem indeterminada. Pode ser uni ou bilateral e muitas vezes acompanhada de bruxismo, aperto dental (cêntrico) ou ranger de dentes (excêntrico) e trismo causados por stress emocional. Outros sinais e sintomas da HM são desconforto facial, desarmonia oclusal e alteração da simetria facial, associados ou não à hiperostose. Em indivíduos submetidos a cirurgia para correção da HM, as principais complicações podem ser a lesão do ducto parotídeo, lesão do ramo bucinador e/ou mandibular do nervo facial, lesão do ramo massetérico da artéria facial e edema pós-operatório que pode perdurar até um ano. As técnicas de imagem para diagnóstico de HM são a ultrassonografia, a tomografia computadorizada e a ressonância magnética nuclear. Foram estudados 30 coelhos da raça Nova Zelândia, que por serem roedores apresentam hipertrofia fisiológica de masseter. Avaliamos a ocorrência de atrofia deste músculo em 2 grupos, num após a sua desinserção do ângulo mandibular direito (grupo D) e em outro grupo após osteotomia do mesmo ângulo (grupo O). Avaliamos os resultados encontrados ao exame de ultra-som, morfológico e histológico, e aplicamos testes estatísticos de TUKEY, FRIEDMANN e SPEARMANN, e concluimos haver atrofia significativa em ambos os grupos. O grau de atrofia no grupo D, mesmo sendo inferior ao grupo O, mostrou ser estatisticamente significativo. A osteotomia, mostrou resultado atrófico maior. A aferição milimetrada com paquímetro e a avaliação do menor diâmetro da fibra demonstraram melhor o grau de atrofia muscular quando comparados ao exame por ultra som / Abstract: Masseteric hypertrophy is an uncommom benign condition that occurs either unilaterally or bilaterally. Many patients have history of bruxism or jaw clenching when under emotional stress. They can have contibuiting problems such as mild malocclusion, missing dentition on the side opposite the muscle enlargement in unilateral cases, or functional temporomandibular joint disorders. Symptoms are unusual but may include mild facial discomfort or complaints referable to an occlusal disharmony. It is most probably a congenital, genetically determined anomaly. The diagnosis of this anomaly is established clinically and radiologically, and it is usually very easy. The condition is treated conservatively or surgically. Diagnostic imaging techniques allow direct, accurate measurement of muscle thickness. We used ultrasound , morphologically and histological methods to measure masseter muscle atrophy between the two sides in masseter muscle of two groups from 30 New Zealand rabbits, submitted to a surgical operation. In one group (D), the masseter muscle, in the lateral mandible angle area was detached with a periosteal elevator trough the posterior edge of the muscle. The other group (O)was submitted to a marginal masseter angle resection.. The muscle was usually not resected . Atrophy results were achieved. New surgical treatment is described, and the pertinent literature summarized. / Mestrado / Cirurgia / Mestre em Cirurgia