Home About us Contact
|
Home About us Contact | ||
|
|
||
Temporal Muscles (temporal + muscle)
Selected AbstractsThe role of peripheral Na+ channels in triggering the central excitatory effects of intravenous cocaineEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2006P. Leon Brown Abstract While alterations in dopamine (DA) uptake appear to be a critical mechanism underlying locomotor and reinforcing effects of cocaine (COC), many centrally mediated physiological and affective effects of this drug are resistant to DA receptor blockade and are expressed more quickly following an intravenous (i.v.) injection than expected based on the dynamics of drug concentration in the brain. Because COC is also a potent local anesthetic, its rapid action on Na+ channels may be responsible for triggering these effects. We monitored temperatures in the nucleus accumbens, temporal muscle and skin together with conventional locomotion during a single i.v. injection of COC (1 mg/kg), procaine (PRO, 5 mg/kg; equipotential anesthetic dose), a short-acting local anesthetic drug that, like COC, interacts with Na+ channels, and cocaine methiodide (COC-MET, 1.31 mg/kg, equimolar dose), a quaternary COC derivative that is unable to cross the blood,brain barrier. In this way, we explored not only the importance of Na+ channels in general, but also the importance of central vs. peripheral Na+ channels specifically. COC induced locomotor activation, temperature increase in the brain and muscle, and a biphasic temperature fluctuation in skin. Though PRO did not induce locomotor activation, it mimicked, to a greater degree, the temperature effects of COC. Therefore, Na+ channels appear to be a key substrate for COC-induced temperature fluctuations in the brain and periphery. Similar to PRO, COC-MET had minimal effects on locomotion, but mimicked COC in its ability to increase brain and muscle temperature, and induce transient skin hypothermia. It appears therefore that COC's interaction with peripherally located Na+ channels triggers its central excitatory effects manifested by brain temperature increase, thereby playing a major role in drug sensing and possibly contributing to COC reinforcement. [source] The influence of masticatory loading on craniofacial morphology: A test case across technological transitions in the Ohio valleyAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Carolina Paschetta Abstract Masticatory loading is one of the main environmental stimuli that generate craniofacial variation among recent humans. Experimental studies on a wide variety of mammals, including those with retrognathic postcanine teeth, predict that responses to masticatory loading will be greater in the occlusal plane, the inferior rostrum, and regions associated with the attachments of the temporalis and masseter muscles. Here we test these experimentally-derived predictions on an extinct human population from the middle and upper Ohio valley that underwent a marked shift from hunting-gathering to extensive farming during the last 3,000 years and for which we have good archaeological evidence about diet and food processing technology. Geometric morphometric methods were used to detect and measure the putative effect of diet changes on cranial shape independent of size. Our results partially confirm only some of the experimental predictions. The effect of softer and/or less tough diets on craniofacial shape seem to be concentrated in the relative reduction of the temporal fossa and in a displacement of the attachment of the temporal muscle. However, there were few differences in craniofacial shape in regions closer to the occlusal plane. These results highlight the utility of exploring specific localized morphological shifts using a hierarchical model of craniofacial integration. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] The Muscles of Mastication in the Caspian Seal (Phoca caspica)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2002H. Endo Summary The muscles of mastication and their related skull characters in the Caspian seal (Phoca caspica) were anatomically examined and compared with those of the Baikal (Phoca sibirica) and ringed (Phoca hispida) seals. A well-developed masseter muscle was observed in the Caspian seal, whereas the temporal muscle consisted of thin bundles. The skull of the Caspian seal possessed the same thin frontal bone and the dorso-ventrally developed zygomatic arch found in the Baikal seal that are required to install the enlarged eyeball into the orbit. The temporal bone was not robust, and the digastric muscle was well-developed in the ventral space of the auditory bulla. The present results suggest that the skull form of the Caspian seal has changed morphologically from its ringed seal-like ancestors, and suggest that the evolutionary strategy of the muscles of mastication in the Caspian seal is principally consistent with that of the Baikal seal. [source] Influence of playing wind instruments on activity of masticatory musclesJOURNAL OF ORAL REHABILITATION, Issue 9 2007A. GOTOUDA Summary, The aim of this study was to elucidate the influence of change in sound tone of playing wind instruments on activity of jaw-closing muscles and the effect of sustained playing for a long time on fatigue of jaw-closing muscles. Electromyograms (EMG) of 19 brass instrument players and 14 woodwind instrument players were measured while playing instruments in tuning tone and high tone and under other conditions. Nine brass instrument players and nine woodwind instrument players played instruments for 90 min. Before and after the exercise, power spectral analyses of EMG from masseter muscles at 50% of maximum voluntary clenching level were performed and mean power frequency (MPF) were calculated. Root mean square (RMS) of EMG in masseter and temporal muscles while playing were slightly larger than those at rest but extremely small in comparison with those during maximum clenching. Root mean square in orbicularis oris and digastric muscles were relatively large when playing instruments. In the brass instrument group, RMS in high tone was significantly higher than that in tuning tone in all muscles examined. In the woodwind instrument group, RMS in high tone was not significantly higher than that in tuning tone in those muscles. Mean power frequency was not decreased after sustained playing in both instrument groups. These findings indicate that contractive load to jaw-closing muscles when playing a wind instrument in both medium and high tone is very small and playing an instrument for a long time does not obviously induce fatigue of jaw-closing muscles. [source] Electromyographic activity of masticatory, neck and trunk muscles of subjects with different skeletal facial morphology , a cross-sectional evaluationJOURNAL OF ORAL REHABILITATION, Issue 7 2007S. TECCO summary, The electromyographic pattern activity of masticatory, neck and trunk muscles was assessed using surface electromyography (sEMG) in 60 Caucasian adult females (20 subjects in skeletal class I, 20 subjects in skeletal class II and 20 subjects in skeletal class III), classified on the base of their skeletal class (ANB angle), corrected on the base of maxillary and mandibular rotations. The sEMG activity was recorded at mandibular rest position and during maximal voluntary clenching. At mandibular rest position, the sEMG activities of masseter and anterior temporal muscles were significantly higher in class III subjects than in class I and class II subjects, that showed no significant difference between them. Then, the sEMG activities of posterior cervicals and upper trapezius were significantly higher in skeletal class III subjects than in the other two groups. During maximal voluntary clenching, no significant difference was observed in the sEMG activity of masticatory muscles among the three considered groups. However, the sEMG activities of posterior cervicals and upper trapezius were significantly higher in skeletal class III subjects than in the other two groups, which showed no significant difference between them. In conclusion, the skeletal class seems to affect the sEMG pattern activity of masticatory, neck and trunk muscles. [source] Preliminary rapport on head posture and muscle activity in subjects with class I and IIJOURNAL OF ORAL REHABILITATION, Issue 11 2005I. C. GADOTTI summary, Forward head posture may cause alterations in the stomatognathic system, including changes in the muscle activity of the masticatory muscles and dental occlusion alterations. Considering the need for further understanding of the relationship between the stomatognathic system and the cervical region, the purpose of this study was to analyse the head posture and the electromyographic (EMG) activity of the anterior portion of temporal and masseter muscles bilaterally among bruxist's subjects with different dental occlusion classifications using the Angle method. The study consisted of 20 female volunteers, between the ages of 17 and 27 years. They were separated into two groups (class I and class II occlusions) according to a dentist-performed evaluation. An assessment of forward head posture was conducted using a photographic technique (angular calculus) combined with a clinical analysis. In the EMG analyses, active differential surface electrodes (Ag) were utilized and were placed bilaterally on the belly of masseter and temporal muscles, perpendicular to the muscles fibres. The EMG signal recorded during bilateral isotonic mastication, was presented using the Root Mean Square and was processed by Matlab software. The results indicated that the EMG responses of temporal and masseter muscles tend to be modified by occlusion alteration class II. Subjects with class II occlusion tended to present more occurrence of forward head posture with alterations in the muscle activity pattern between masseter and temporal muscles. [source] A clinical diagnosis of diurnal (non-sleep) bruxism in denture wearersJOURNAL OF ORAL REHABILITATION, Issue 6 2000K. Piquero The purpose of this study was to establish a clinical method for diagnosing diurnal bruxism in denture wearers by recording masseter and anterior temporal electromygraph (EMG) activity. Seven suspected bruxists and five normal patients who wore complete dentures and/or distal extension base removable partial dentures were selected for participation. EMG activity in both the masseter and the anterior temporal muscles was recorded bilaterally during silent reading (10 min), maximal voluntary clenching (MVC), tapping in centric occlusion, lateral movements, chewing and swallowing. No significant differences of EMG activity were found between the groups during tapping, lateral movement, chewing and swallowing (P>0·05). However, during 10 min of silent reading, a significant difference was found between the groups when comparing masseter muscle activity (P<0·05). A threshold of 10% of MVC of at least 3-s duration was used to define an individual bruxism event. When the muscle activity recorded during silent reading was further analysed using these criteria, the control group displayed no bruxing activity while the suspected bruxist group displayed a mean frequency of six bruxism events (range 2,10). It was concluded that: (a) masseter muscle activity recorded during 10 min of silent reading showed significant difference between the groups; (b) the criteria selected in this study for the detection of sleep bruxism can also be used to assess diurnal bruxism; and (c) it is possible to diagnose diurnal bruxism in denture wearers by measuring the masseter EMG activity during 10 min of silent reading. [source] Influence of changing the chewing region on mandibular movementAUSTRALIAN DENTAL JOURNAL, Issue 1 2009K Hashii Abstract Background:, In the shortened dental arch condition, little is known of how patients adapt their jaw function during mastication to the new oral environment. This study aimed to investigate the changes in mandibular movements when the chewing region was changed from the first molar to the first premolar. Methods:, Thirty clinical residents with natural dentitions were recruited. The subjects were asked to chew a piece of beef jerky using either the first molar or the first premolar on the preferred chewing side. Three-dimensional trajectories of lower incisors and both condyles were analysed using a jaw movement tracking device with six degrees of freedom during the period between the onset and offset of electromyographic bursts from the masseter and anterior temporal muscles. Results:, The closing angle of the lower incisors for first premolar chewing was narrower in comparison with that for first molar chewing (p < 0.05). The lengths of the condylar trajectories and the maximum velocities of the condylar movement for first premolar chewing were smaller and slower, respectively, in comparison with those for first molar chewing (both sides; p < 0.01). Conclusions:, The mandibular movement during mastication might be changed to adapt the premolar chewing because of a loss of posterior occlusal supports. [source] Neuromuscular coordination of masticatory muscles in subjects with two types of implant-supported prosthesesCLINICAL ORAL IMPLANTS RESEARCH, Issue 2 2004Virgilio F. Ferrario Abstract Objectives: To compare the electromyographic (EMG) characteristics of masticatory muscles in patients with fixed implant-supported prostheses and implant overdentures. Material and methods: Nineteen subjects aged 45,79 years were examined. Fourteen were edentulous and had been successfully rehabilitated with (a) maxillary and mandibular implant-supported fixed prostheses (seven patients); (b) mandibular implant overdentures and maxillary complete dentures (seven patients). Five control subjects had natural dentition or single/partial (no more than two teeth) tooth or implant fixed dentures. Surface EMG of the masseter and temporal muscles was performed during unilateral gum chewing and during maximum teeth clenching. To reduce biological and instrumental noise, all values were standardized as percentage of a maximum clenching on cotton rolls. Results: During clenching, temporal muscle symmetry was larger in control subjects and fixed implant-supported prosthesis patients than in overdenture patients (analysis of variance, P=0.005). No differences were found in masseter muscle symmetry or in muscular torque. Muscle activities (integrated areas of the EMG potentials over time) were significantly larger in control subjects than in implant-supported prosthesis patients (P=0.014). In both patient groups, a poor neuromuscular coordination during chewing, with altered muscular patterns, and a smaller left,right symmetry than in control subjects were found (P=0.05). No differences in masticatory frequency were found. Conclusion: Surface EMG analysis of clenching and chewing showed that fixed implant-supported prostheses and implant overdentures were functionally equivalent. Neuromuscular coordination during chewing was inferior to that found in subjects with natural dentition. Résumé Le but de cette étude a été de comparer les caractéristiques éléctromiographiques (EMG) de muscles masticateurs chez des patients avec des prothèses fixées sur implant et des prothèses amovibles sur implants. Dix-neuf patients de 45 à 79 ans ont été examinés. Quatorze étaient édentés et ont été traités avec succès par a) une prothèse fixée sur des implants au niveau maxillaire et mandibulaire (sept patients), b) des prothèses amovibles ancrées sur implant au niveau de la mandibule et des prothèses amovibles totales supérieures (sept patients). Les cinq contrôles avaient soit une dentition naturelle soit des couronnes sur implants ou dent unique. L'EMG de surface des muscles masséter et temporaux a été effectué durant la mastication unilatérale de gomme à mâcher et à la force maximale de fermeture. Pour diminuer le bruit biologique et instrumental, toutes les valeurs ont été standardisées en pourcentage d'une force maximale de fermeture sur des rouleaux de coton. Durant la fermeture, la symétrie musculaire temporale était plus importante chez les sujets contrôles et les prothèses fixées sur implants que chez les patients avec prothèse amovible (analyse de variance, p=0,005). Aucune différence n'a été constatée dans la symétrie musculaire du masséter ou dans la torsion musculaire. Les activités musculaires (zones intégrées des potentiels EMG avec le temps) étaient significativement plus importantes chez les contrôles que chez les patients avec prothèses fixées sur implants (p=0,014). Dans les deux groupes de patients, une pauvre coordination neuromusculaire durant le mâchonnement, avec des modèles musculaires altérés, et une plus petite symétrie gauche-droite étaient constatées chez les sujets contrôles (p=0,05). Aucune différence dans la fréquence masticatoire n'a été trouvée. L'analyse EMG de surface de fermeture et de mastication montraient que les prothèses fixées sur implant et les prothèses amovibles sur implants étaient fonctionnellement équivalentes. Cependant la coordination neuromusculaire durant la mastication était inférieure à celle trouvée chez les sujets avec dentition naturelle. Zusammenfassung Ziel: Die EMG-Charakteristiken der Kaumuskeln in Patienten mit festsitzenden implantatgetragenen Prothesen und implantatgetragenen Hybridprothesen zu vergleichen. Material und Methode: Neunzehn Patienten im Alter von 45 bis 79 Jahren wurden untersucht. Vierzehn davon waren zahnlos und erfolgreich wiederhergestellt worden mit a) festsitzenden implantatgetragenen Ober- und Unterkieferprothesen (sieben Patienten); b) Unterkieferhybridprothesen und OK-Totalprothesen (sieben Patienten). Die fünf Kontrollpatienten hatten eine natürliche Bezahnung oder Einzelkronen bzw. kleine Brücken (nicht mehr als zwei Zähne) auf Implantaten oder Zähnen. Während einseitigem Kaugummikauen und maximalem Zähnepressen wurden Messungen der Oberflächen-EMGs der Masseter- und Temporalmuskulatur durchgeführt. Um das biologische und instrumentelle Rauschen zu unterdrücken, wurden alle Werte als Prozentanteil des maximalen Pressens auf Watterollen standardisiert. Resultate: Während des Pressens war die temporale Muskelsymmetrie bei den Kontrollpatienten und den Patienten mit festsitzenden implantatgetragenen Prothesen grösser als bei den Probanden mit Hybridprothesen (Varianzanalyse, p=0.005). Bei der Symmetrie der Massetermuskeln und im muskulären Drehmoment konnten keine Unterschiede gefunden werden. Die Muskelaktivitäten (integrierte Areale der EMG-Potentiale über die Zeit) waren bei den Kontrollpatienten signifikant tiefer als bei den Probanden mit implantatgetragenen Prothesen (p=0.014). Bei beiden Patientengruppen konnte eine schlechtere neuromuskuläre Koordination während des Kauens mit veränderlichen muskulären Mustern und einer geringeren links-rechts Symmetrie als bei den Kontrollpatienten gefunden werden (p=0.05). Bei der Kaufrequenz bestanden keine Unterscheide. Schlussfolgerung: Die Analyse der Oberflächen-EMG beim Pressen und Kauen zeigte, dass festsitzende implantatgetragene Prothesen und implantatgetragene Hybridprothesen funktionell gleichwertig sind. Die neromuskuläre Koordination während des Kauens war schlechter als bei Probanden mit natürlicher Bezahnung. Resumen Objetivos: Comparar las características del EMG de los músculos masticatorios en pacientes con prótesis fija implanto-soportada y sobredentaduras en implantes. Material y métodos: Se examinaron 19 sujetos de edades entre 45 y 79 años. Catorce eran edéntulos, y habían sido rehabilitados con éxito con a) prótesis fija implanto-soportada maxilar y mandibular (siete pacientes); b) sobredentadura completa en implantes maxilar y mandibular (siete pacientes). Cinco pacientes de control tenían dentición natural o dentaduras fijas sobre implantes o dientes unitarias o parciales (no mas de 2 dientes). Se llevó a cabo EMG de superficie de los músculos maseteros y temporales durante mascado de chicles unilateralmente, y durante cierre máximo. Para reducir las interferencias biológicas e instrumentales, todos los valores se estandarizaron como porcentajes de un cierre máximo sobre rollos de algodón. Resultados: Durante el cierre, la simetría de los músculos temporales fue mayor en los sujetos de control y en los pacientes de prótesis fijas implanto-soportadas que en los pacientes con sobredentaduras (análisis de varianza, p=0.005). No se encontraron diferencias en la simetría del músculo masetero o en el torque muscular. Las actividades musculares (áreas integradas de los potenciales del EMG a lo largo del tiempo) fueron significativamente mayores en los sujetos de control que en los pacientes con prótesis implantosoportada (p=0.014). En ambos grupos de pacientes, se encontró una coordinación neuromuscular mas pobre durante el mascado, con patrones musculares alterados, y una menor simetría derecha-izquierda que en los sujetos de control (p=0.05). No se encontraron diferencias en la frecuencia masticatoria. Conclusión: El análisis del EMG de superficie de máxima mordida y de mascado mostró que las prótesis fijas implanto-soportadas y las sobredentaduras en implantes fueron funcionalmente equivalentes. La coordinación neuromuscular durante el mascado fue inferior a aquella encontrada en sujetos con dentición natural. [source] | |||||||||||||