Copies of author's previously published articles inserted. / Bibliography: leaves 121-137. / ix, 138 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates the pattern of reflexes evoked by stretch in a human jaw-closing muscle (masseter) at the level of the whole muscle and individual motor units. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physiology, 1994

Tübingen, Univ., Diss., 2002.

The human masseter muscle is a structurally complex jaw elevator with the capability of generating high, multidirectional forces. The invasiveness of current anatomical and physiological methods has, however, limited both the number and scope of studies of human masseter muscle structure and function. Therefore the aim of this work was to apply in vivo magnetic resonance (MR) techniques to elucidate the three-dimensional internal architecture of the human masseter muscle and its metabolic response to exercise in order to gain a better understanding of the jaw muscles in health and disease. In the first of these experiments, five adult subjects were selected and examined using cephalometric radiography, magnetic resonance imaging (MRI) and three-dimensional rotational and reconstructive computer graphics to describe the organization of tendon planes within the masseter muscle. Planar quadrilaterals representing putative tendon planes were fitted to the surfaces of the three-dimensional muscle reconstructions, and these were related to the mid-sagittal plane in the coronal and axial views. To confirm whether putative planes disclosed by MRI represented true anatomic entities, a fresh human cadaver head was imaged by MRI and then cryosectioned at millimetre intervals. Planar sections through the reconstructed muscle generated from the cadaver cryosections were correlated with the actual MR images in the same planes. Tendon plane angulation appeared to be related to ramal length and lower face height measured cephalometrically. In the axial view, the tendon planes appeared roughly to follow the angulations of the zygomatic arch and the lateral face of the mandibular ramus. Our results suggest that the angulation of tendon planes, and possibly pennation angles are different depending on the viewing angle, and infer that muscle fibres inserting on either side of a central tendon may need to develop different tensile forces if translation is to occur directly along the tendon axis. In the second, 31P magnetic resonance spectroscopy (MRS) was utilized to examine the masseter muscles of six adult males at rest and performing stereotyped isometric clenching exercises. 31P MR spectra were acquired from three locations within the muscle using a 2cm by 3cm, single-turn, copper receiver coil. The spectra were quantified on the basis of relative peak area and position. The organic phosphate (Pi) to creatine phosphate (PCr) ratio (Pi/PCr), which has been shown to be proportional to free ADP concentration and hence, the metabolic activity, as well as the normalized Pi concentration ([Pi]) and pH, were calculated for each site and exercise. The mean resting Pi/PCr ratio and [Pi] were greater for the deep part of the muscle than for the superficial and intermediate parts. These differences were significant to p<0.01. The mean pH however, was similar in all parts of the muscle at rest. During exercise, a significant increase in mean Pi/PCr was found in the superficial and intermediate parts of the muscle. Both these differences were significant to p<0.05. An accompanying decrease in mean pH was observed in all parts of the muscle during exercise. In the superficial part of the muscle, this decrease was significant to the p<0.05 level, and in the deep part, the decrease was significant to the p<0.001 level. No significant differences were found for these parameters between left and right molar clenching. These results suggest that metabolic activity may be monitored in the masseter muscle using 31P MR spectroscopy and that task-dependent and regional variations in metabolic activity may be demonstrated both at rest and during exercise. They are promising enough to encourage future studies of muscle metabolism in subjects with jaw muscle disorders. These experiments demonstrate the novel application of magnetic resonance techniques for studying craniomandibular morphology and function non-invasively. Collectively, they reveal the anatomical and functional heterogeneity which exist in the human masseter muscle. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

Orientador: Paulo Henrique Ferreira Caria / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-13T11:46:29Z (GMT). No. of bitstreams: 1 Casarin_CezarAugustoSouza_D.pdf: 7161593 bytes, checksum: c1cf18cd08591802aa81ca639ffaa269 (MD5) Previous issue date: 2009 / Resumo: A má-oclusão é a alteração da posição dos dentes e do formato de arcadas que afeta a estrutura musculoesquelética do sistema mastigatório de indivíduos acometidos por essa condição. O objetivo deste estudo foi analisar as alterações morfofuncionais da mandíbula e de dois mm. mastigatórios de 48 ratos (Novergicus Wistar), divididos em três grupos de 16 animais, grupo 1: submetidos ao aumento bilateral da dimensão vertical oclusal, grupo 2: submetidos ao deslocamento retrusivo da mandíbula e grupo 3: controle. Foram realizadas à análise morfométrica da densidade óssea do processo alveolar, do ramo e base da mandíbula e a análise histoquímica (NADH-tr) dos músculos masseter e temporal, ambas com o auxílio do software (ImageJ). A análise densitométrica apresentou perda óssea somente na base da mandíbula no grupo 1 (0,454 ± 0,020) enquanto no grupo 2 (0,482 ± 0,025) e nas demais regiões, houve o aumento do conteúdo ósseo. Os resultados histoquímicos apresentaram as fibras glicolíticas rápidas (FG) (1,06E+06 ± 2,53+05) com maior área que as fibras oxidativas-glicolíticas rápidas (FOG) (6,86E+05 ± 1,50E+05), enquanto as oxidativas lentas (SO) (5,50E+05 ± 1,40E+05) foram menores que as demais. Entre todas as fibras analisadas o grupo 2 (8,89E+05 ± 2,56E+05) apresentou maior área que os grupos 1 (6,89E+05 ± 1,18E+05) e controle (7,20E+05 ± 1,69E+05). As fibras do m. temporal (8,54E+05 ± 2,11E+05) apresentaram maior área que as do m. masseter (6,78E+05 ± 1,51E+05). Houve predomínio de fibras FG (22 ± 4) em relação as fibras FOG (13 ± 3) e SO (15 ± 4) em todos os grupos e músculos avaliados. O m. temporal apresentou mais SO (15 ± 3,9) que FOG (12 ± 3), e o m. masseter apresentou números equivalentes destas fibras. As alterações oclusais provocam modificações morfológicas no tecido ósseo da mandíbula e dos mm. mastigatórios. / Abstract: The malocclusion is an alteration of dental position and the shape of the arches that affects the musculoskeletal structures of the masticatory system of individuals affected by this condition. The objective of this study was analysis the morphofunctional alterations of mandible and two masticatory muscles. Forty eight male rats Novergicus Wistar divided into three groups of 16 animals, group 1: submitted to bilateral increased occlusal vertical dimension, group 2, submitted to posterior displacement of the mandible and group 3: control. The morphometric analyze of bone density of the alveolar process, ramus and base of mandible and the fibres modifications by histochemistry (NADH-tr) of the masseter and temporal muscles, were effected by the ImageJ software. The densitometric analysis presented bone loss only in the base of the mandible in group 1 (0,454 ± 0,020) and increase in the bone content of mandible in group 2 (1,06E+06 ± 2,53+05) and other regions. The histochemical results showed the fast glycolytic fibers (FG) (1,06E+06 ± 2,53+05), area larger than fast glycolytic-oxidative fibers (FOG) (6,86E+05 ± 1,50E+05), while the slow oxidative (SO) (5,50E+05 ± 1,40E+05) was lower than the others. Among all fibers analyzed, the group 2 (8,89E+05 ± 2,56E+05) showed largest area than groups 1 (6,89E+05 ± 1,18E+05) and control (7,20E+05 ± 1,69E+05). The fibers of temporal muscle (8,54E+05 ± 2,11E+05) presented largest area than the masseter muscle (6,78E+05 ± 1,51E+05). There was predominance of FG fibers (22 ± 4) in relation the FOG (13 ± 3) and SO fibers (15 ± 4), to other in all groups and muscles studied. The temporal muscle presented numerically more SO (15 ± 3,9) than FOG (12 ± 3), and masseter muscle showed equal numbers of these fibers. The occlusal alterations provoked morphological changes in bone tissue of mandible and masticatory muscles. / Doutorado / Anatomia / Doutor em Biologia Buco-Dental

Thesis--Catholic University of Leuven, 1985.

Thesis--Catholic University of Leuven, 1985.

Typescript (Photocopy) / Copy of published paper co-authored by author, in back / Bibliography: leaves 209-228 / xiv, 232 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1989

Thesis--Göteborg. / Extra t.p. with thesis statement inserted. Includes reprints of the author's articles. Includes bibliographical references.

Thesis--Göteborg. / Extra t.p. with thesis statement inserted. Includes reprints of the author's articles. Includes bibliographical references.

Submitted by Lucelia Lucena (lucelia.lucena@ufpe.br) on 2015-03-11T18:17:42Z No. of bitstreams: 2 Capa tese 18-09-13.pdf: 1375204 bytes, checksum: deb9ad019a4e61cc522e5cac129a16b1 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-11T18:17:42Z (GMT). No. of bitstreams: 2 Capa tese 18-09-13.pdf: 1375204 bytes, checksum: deb9ad019a4e61cc522e5cac129a16b1 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2012-12-19 / Analisar os efeitos precoces da desnutrição protéica neonatal sobre a morfofisiologia da mastigação em ratos. Ratos machos da linhagem Wistar foram divididos em grupos experimentais conforme a manipulação nutricional imposta às mães durante o período de lactação. O grupo nutrido, consistiu de oito filhotes machos cujas mães foram alimentadas com caseína 17%, ao passo que o grupo desnutrido foi composto por mães que foram alimentadas com dieta caseína 8%. O peso corporal dos animais foi mensurado durante o período de lactação, para estabelecer o ganho de peso corporal. Dos 14 aos 21 dias de idade, foi realizada a avaliação das propriedades de membrana intrínseca de neurônios localizados na parte dorsal do núcleo sensorial principal do trigêmeo (NVsnpr) por meio de patch-clamp. Aos 17, 19 e 21 dias de idade, os animais foram filmados para posterior análise dos parâmetros da mastigação. E, aos 25 dias de idade, o feixe superficial do músculo masseter foi dissecado para avaliação da composição dos tipos de fibras musculares, por meio da técnica de ATPase miofibrilar, bem como da área e perímetro das fibras musculares. A restrição de proteína precoce foi associada com a redução no peso corporal. Os animais desnutridos apresentaram uma menor capacidade de gerar disparos ritmicos e uma redução na frequência de disparos. Contudo, demonstraram um potencial de membrana para geração de disparos mais despolarizado. Ademais, os filhotes desnutridos apresentaram um menor número de sequências e ciclos mastigatórios. Os ratos desnutridos apresentaram uma maior proporção de fibras do tipo IIa e uma menor quantidade de fibras do tipo IIb que os animais controle; e, uma menor área e perímetro tanto das fibras do tipo IIa quanto do tipo IIb quando comparado ao grupo nutrido. A desnutricão protéica neonatal atrasa o desenvolvimento morfológico e funcional da mastigação. Contudo, parece que estes animais são capazes de se adaptarem, de forma que conseguem manter os movimentos mandibulares durante a sequência mastigatória.