Sciuromorphy outside rodents reveals an ecomorphological convergence between squirrels and extinct South American ungulates.

Notoungulates were a diverse group of South American ungulates that included the rodent-like typotherians. However, they are typically compared with other ungulates and interpreted as grazers. Here we present the first detailed reconstruction of the masticatory muscles of the pachyrukhine typotherians Paedotherium and Tremacyllus. An outstanding feature is the presence of a true sciuromorph condition, defined by an anterior portion of the deep masseter muscle originating from a wide zygomatic plate that reaches the rostrum, a trait traceable since the Oligocene pachyrukhines. Consequently, pachyrukhines are the first case of sciuromorph non-rodent mammals. This morphology would have allowed them to explore ecological niches unavailable for the exclusively hystricomorph coexisting rodents. This innovative acquisition seems to be synchronous in Pachyrukhinae and sciuromorph rodents and related to hard-food consumption. We postulate the expansion of nut and cone trees during the major environmental changes at Eocene-Oligocene transition as a potential trigger for this convergence.

Morphological and morphometric characterization of the "sphenoidal tubercle" / Caracterización morfológica y morfométrica del tubérculo esfenoidal

The sphenoidal tubercle is a bone elevation located in the anterior edge of the infratemporal crest of the sphenoid greater wing, where the temporal and lateral pterygoid muscles have their origin. This bone accident presents varied morphology so its description and denomination are a topic of discussion. 60 dry skulls obtained from the morphology laboratory of the Biomedical Basic Sciences Department of the University of Talca were used for a morphological and morphometric analysis of the sphenoidal tubercle including its morphology, diameters (anteroposterior, transverse and vertical) and the distance to the grooves for the maxillary artery and maxillary nerve. Sphenoidal tubercle had a prevalence of 98.4 % of all dry skulls analyzed with a bilateral presentation in the 76.6 % of the cases. According to its different forms of presentation established by Cáceres et al., (2016) the pyramidal form was the most frequent with a 25.7 %. The average diameters were of 4.12 mm anteroposterior, 5.50 mm transverse and 3.89 mm vertical. The average distance to the grooves of the maxillary artery and maxillary nerve were 9.04 mm and 7.6 mm, respectively. Sphenoidal tubercle is a constant bone accident with a variated morphology and measures. Due to its anatomical relations with important neurovascular elements such as the maxillary artery and the maxillary nerve, it may be used as a reference point for surgical access to the infratemporal fossa. From this analysis we establish that the denomination of "infratemporal process" is more accurate, because the development of this bone accident is from muscular traction performed by the lateral pterygoid muscle and the deep portion of the temporal muscle causing great variations in its morphology, probably due to external and functional parameters or even influenced by the biotype.

El tubérculo esfenoidal es una elevación ósea ubicada en el extremo anterior de la cresta infratemporal del ala mayor del hueso esfenoides, donde presta inserción al músculo temporal y pterigoideo lateral. Presenta morfología variada, por lo que su descripción y denominación resultan motivo de discusión. 60 cráneos secos obtenidos del Laboratorio de Morfología del Departamento de Ciencias Básicas Biomédicas de la Universidad de Talca, fueron utilizados para realizar un análisis morfológico y morfométrico del tubérculo esfenoidal evaluando forma, diámetros (anteroposterior, laterolateral y vertical) y distancia con el surco de la arteria y nervio maxilar. El tubérculo esfenoidal tuvo una prevalencia del 98,4 % del total de cráneos analizados, presentándose bilateralmente en el 76,6 % de los casos. De acuerdo a las diferentes formas de presentación establecidas por Cáceres et al (2016) la forma piramidal fue la más frecuente con un 25,7 %. Los diámetros promedio fueron de 4,12 mm anteroposterior, 5,50 mm laterolateral y 3,89 mm vertical. Las distancias promedio con el surco de la arteria y nervio maxilar fueron de 9,04 mm y 7,6mm, respectivamente. El tubérculo esfenoidal es un accidente óseo constante de morfología y dimensiones variadas. Debido a sus relaciones con elementos vasculares de importancia, tales como la arteria y nervio maxilar, podría ser utilizado como elemento de referencia para el acceso quirúrgico a la fosa infratemporal. A partir de su análisis planteamos que su denominación como "proceso infratemporal" sería más apropiado, debido a que se desarrollaría a partir de la tracción muscular ejercida por el musculo pterigoideo lateral y la porción profunda del músculo temporal, ocasionando variaciones notables en su morfología, probablemente debido a factores externos y funcionales o incluso influenciada por el biotipo.

Microsurgical Anatomy of the Interfascial Vein. Its Significance in the Interfascial Dissection of the Pterional Approach.

BACKGROUND: The pterional approach (PA), together with its variants, is still one of the most common methods used by surgeons to reach the anterior and middle cranial base. A highly important technical detail during a PA is the preservation of the frontotemporal branch of the facial nerve, which can be achieved through an interfascial dissection. OBJECTIVE: To describe the anatomy of the interfascial vein (IFV), highlighting its recognition as a significant anatomic reference to perform an interfascial dissection (IFD). METHODS: Eight adult cadaveric heads, fixed with formaldehyde and injected with colored silicone, were studied. In 6 heads, an IFD was performed, simulating a PA. In the 2 remaining heads, the IFV was dissected. In addition, an IFD was performed in 10 patients, studying the IFV anatomy. RESULTS: In the 6 cadaveric heads in which the PA with an IFD was performed, and in the 10 patients who underwent a PA with an IFD, the IFV was found. If the interfascial space is divided into thirds, in all cases, the IFV was located within the middle third of the interfascial fat pad. On the 2 cadaveric heads in which the IFV was anatomically dissected, the IFV was also located within the middle third of the interfascial space. CONCLUSION: Recognizing the IFV in the interfascial space is of great help as an anatomic landmark to confirm that one is actually between both layers of the superficial temporal fascia.

Characterization and morphological comparison of human dura mater, temporalis fascia, and pericranium for the correct selection of an autograft in duraplasty procedures.

PURPOSE: The objective of this study was to characterize and compare the morphological characteristics of the dura mater, the pericranium, and the temporal fascia to ascertain the most adequate tissue to use as a dura graft. METHODS: 20 dura mater, 20 pericranium and 20 temporalis fascia samples were analyzed. Each of the samples was stained with hematoxylin and eosin, orcein, Van Gieson, Masson's trichrome and Verhoeff-Van Gieson (600 slides in total) for a general morphological evaluation, as well as a quantitative, morphometric and densitometric analysis of elastic fibers present in each of the tissues. RESULTS: The micro-densitometric analysis of the tissues indicated that the area occupied by the elastic fibers showed values of 1.766 ± 1.376, 4.580 ± 3.041, and 8.253 ± 4.467 % for the dura mater, the temporalis fascia and the pericranium, respectively (p < 0.05, all pairs). The values observed in the analysis of the density intensity were 3.42E+06 ± 2.57E+06, 1.41E+07 ± 1.28E+07, and 1.63E+07 ± 9.19E+06 for the dura mater, the temporalis fascia and the pericranium, respectively (p < 0.05), dura mater vs. temporalis fascia and dura mater vs. pericranium). CONCLUSIONS: This is the first study to compare the dura mater with tissues for dural autograft and to quantify the elastic component present in these tissues. The results indicate that the temporalis fascia is a better dural graft because of its intrinsic tissue properties.

Relationship between electrical activity of the temporal and masseter muscles, bite force, and morphological facial index. / Relações entre potenciais elétricos dos músculos temporais e masseteres, força de mordida e índice morfológico da face.

PURPOSE: To analyze possible correlations between the electrical activity of masseter and temporal muscles, Bite Force (BF), and Morphological Facial Indices (MFI). METHODS: The study involved 43 young adults, both genders, 18 to 37 years old. The individuals were submitted to: face measurement to calculate MFI; Masseter and Temporal Surface Electromyography (sEMG) and BF measurements on right and left premolars and incisors. The following electromyographic tests were conducted: at rest position; Maximal Voluntary Isometrical Contraction (MVIC) and usual chewing of raisins. Statistical analysis was conducted using the coefficient of Spearman correlation with significance level of 5%. RESULTS: The values at rest in the temporal muscles were significantly higher than those in the masseter muscles. A meaningful correlation was found between MFI and sEMG in the MVIC test for the Left Temporal (rs=36, p=0.017). A significant correlation was observed between FMI and sEMG during BF in incisors for temporal muscles and the Right Masseter. During the force tests, it was possible to observe a meaningful correlation between BF in right premolars and the sEMG of the Left Temporal and Masseters. CONCLUSION: No correlation was found between the sEMG of temporal and masseter muscles, BF, and FMI in adult individuals based on the tests performed. The SEMG of temporal and masseter muscles seems to be associated only with BF. As a datum of habitual postural characteristic, the electrical activity of temporal muscles is higher than the activity of masseters, also regardless of MFI.

Relações entre potenciais elétricos dos músculos temporais e masseteres, força de mordida e índice morfológico da face / Relationship between electrical activity of the temporal and masseter muscles, bite force, and morphological facial index

RESUMO Objetivo Verificar e analisar possíveis correlações entre a atividade elétrica dos músculos temporais e masseteres, a força de mordida e os índices morfológicos da face, em indivíduos adultos. Método Participaram 43 indivíduos, adultos jovens de ambos os gêneros, entre 18 e 37 anos, submetidos à mensuração da face para cálculo do Índice Morfológico da Face (IMF), Eletromiografia de Superfície (EMGs) de Masseteres Direitos e Esquerdos (MD e ME), Temporais Direitos e Esquerdos (TD e TE) e obtenção da Força de Mordida (FM) nas regiões de pré-molares direitos, pré-molares esquerdos e incisivos. As provas eletromiográficas realizadas foram em repouso, Contração Voluntária Isométrica Máxima (CVIM) e mastigação habitual de uva-passa. Foi realizada análise estatística pelo coeficiente de correlação de Spearman com significância no nível de 5%. Resultados Os valores de repouso em TD e TE foram significativamente maiores que os de MD e ME. Foi encontrada correlação direta significativa entre IMF e a EMGs na prova de CVIM para o TE (rs=36, p=0,017). Observou-se correlação direta significativa entre o IMF com a EMGs durante a FM em Incisivos para os músculos TD, TE e Masseter Direito (MD). Durante as provas de força, foi possível observar correlação direta significativa entre a FM em pré-molares direitos com a EMGs do TE, MD, ME. Conclusões Não foi verificada correlação entre as respostas elétricas dos músculos temporais e masseteres, a força de mordida e os índices morfológicos da face, em indivíduos adultos a partir das provas realizadas. A atividade elétrica dos músculos temporais e masseteres parece associar-se apenas à força de mordida. Como dado de característica postural habitual, a atividade elétrica dos músculos temporais é maior que a atividade de masseteres, também independente do IMF.

ABSTRACT Purpose To analyze possible correlations between the electrical activity of masseter and temporal muscles, Bite Force (BF), and Morphological Facial Indices (MFI). Methods The study involved 43 young adults, both genders, 18 to 37 years old. The individuals were submitted to: face measurement to calculate MFI; Masseter and Temporal Surface Electromyography (sEMG) and BF measurements on right and left premolars and incisors. The following electromyographic tests were conducted: at rest position; Maximal Voluntary Isometrical Contraction (MVIC) and usual chewing of raisins. Statistical analysis was conducted using the coefficient of Spearman correlation with significance level of 5%. Results The values at rest in the temporal muscles were significantly higher than those in the masseter muscles. A meaningful correlation was found between MFI and sEMG in the MVIC test for the Left Temporal (rs=36, p=0.017). A significant correlation was observed between FMI and sEMG during BF in incisors for temporal muscles and the Right Masseter. During the force tests, it was possible to observe a meaningful correlation between BF in right premolars and the sEMG of the Left Temporal and Masseters. Conclusion No correlation was found between the sEMG of temporal and masseter muscles, BF, and FMI in adult individuals based on the tests performed. The SEMG of temporal and masseter muscles seems to be associated only with BF. As a datum of habitual postural characteristic, the electrical activity of temporal muscles is higher than the activity of masseters, also regardless of MFI.

Biomechanical potential of the temporal muscle in brachyfacial and dolichofacial subjects: a study on dry mandibles.

OBJECTIVES: To measure the lengths of the force and resistance arms, in order to calculate the mechanical advantage and muscular work of the human temporalis muscle (TM) in brachyfacial (BR) and dolichofacial (DO) subjects. SETTING AND SAMPLE POPULATION: Mandibles from 49 subjects of both genders (BR n = 9; DO n = 40) from the collection of the Laboratory of Human Anatomy at Universidade de Santa Cruz do Sul, Rio Grande do Sul, Brazil, were analyzed. MATERIAL AND METHODS: The distance between the condylar process and the coronoid process (insertion site of the TM) represented the length of the force arm (LFA ) of the TM. The distance between the condylar process and the mental protuberance represented the length of the resistance arm (LRA ). Thus, the mechanical advantage of the TM was obtained using the following ratio: LFA /LRA , while the muscular work (LRA /LFA ) of the TM was obtained using the inverse of this ratio. RESULTS: When compared with the DO, the parameters of the BR are significantly greater, as shown by the LFA (6.0%) and mechanical advantage (8.2%; p = 0.0078). By contrast, our results show that in the DO, the LRA was 2.4% longer and the muscular work was 10.4% greater (p = 0.0087). CONCLUSION: The mechanical advantage of the TM in BR subjects is significantly greater than in DO subjects. Moreover, this greater mechanical advantage may explain, at least in part, the higher incidence of temporomandibular dysfunctions in BR subjects.

Sphenomandibular muscle or deep bundle of temporal muscle? / ¿Músculo esfenomandibular o fascículo profundo del músculo temporal?

The muscle designated by a group of authors as the sphenomandibular or, according to recent studies, the deep bundle of the temporal muscle, presents important anatomical relationships, especially in a medical-odontological context. In view of this divergence, the aim of the present study was to observe the morphology by means of dissection of the formaldehyde-preserved heads, using two different techniques to access the muscle region in question, designated as trans-zygomatic and frontal access routes. The results permitted, by observation of the dissections frontally, the presence of fascicles standing apart from the deep bundle muscle venter, which was named intermediary bundle. This bundle presented two portions, a meaty upper portion and a tendinous lower portion, which continues with the tendinous part of the superficial bundle present on the internal surface of the coronoid process. In view of the material observations, it can be concluded that, due to the total absence of muscular fascia between its bundles, the temporal muscle is a unique entity presenting three bundles ­ the deep, the intermediate and the superficial.

El músculo denominado como esfenomandibular por un grupo de autores o de acuerdo con estudios recientes, de fascículo profundo del músculo temporal, presenta importantes relaciones anatómicas, especialmente en un contexto médico-odontológico. En vista de esta discusión, el objetivo fue observar la morfología mediante la disección de cabezas conservadas en formaldehído, utilizando dos técnicas diferentes para acceder a la región del músculo, designadas como vías de acceso trans-cigomáticas y frontales. Los resultados mostraron, por la observación de las disecciones frontales, la presencia de fascículos que se ubican independientemente al vientre muscular del fascículo profundo, denominado fascículo intermediario. Este fascículo presentó dos porciones, una superior carnosa y una inferior tendinosa, que continuó con la parte tendinosa del fascículo superficial presente en la superficie interna del proceso coronoides. En vista de las observaciones realizadas, se puede concluir que debido a la ausencia total de la fascia muscular entre sus paquetes, el músculo temporal es una entidad única que presenta tres fascículos, el profundo, intermedio y superficial.

Muscle fiber type composition, fiber diameter, capillary density in temporalis and masseter muscles and correlation with bite force / Tipos de fibras musculares, diámetro de fibras y densidad capilar en los músculos masetero y temporal y su correlación con la fuerza de mordida

The jaw muscles are essential components in the stomatognatic system. Their complex architecture allows them to execute several motor tasks. One of the structural peculiarities is the presence of hybrid and neonatal fibers.We studied the differences of the fiber-type in masseter and temporalis muscles along the first to nineth decades in both genders. Seventy-four (74) samples were analyzed by immunohistochemistry. Slow and fast muscle fibers distribution was similar in both muscles in both genders. Hybrid fiber was observed in all decades, and its frequency decreased significantly (p<0.001) with aging in masseter. Neonatal myosin expression was observed in all decades, its expression was more frequent in masseter (p=0.01), and males in temporalis (p=0.025). Decrease of the cross sectional area of fast and slow fibers, and decrease of capillary density were detected with aging. These morpho-immunohistochemical alterations on masseter and temporalis muscles correlated to the decrease in bite force with aging.

Los músculos cráneomandibulares son componentes esenciales en el sistema estomatognático. Su arquitectura compleja les permite ejecutar variadas tareas motoras. Una de sus características estructurales es la presencia de fibras musculares híbridas y neonatales. Se estudiaron las diferencias del tipo de fibra en los músculos masetero y temporal en la primera a novena décadas dela vida en ambos sexos. Setenta y cuatro (74) muestras se analizaron por inmunohistoquímica. La distribución de lãs fibras musculares lentas y rápidas fue similar en ambos músculos en ambos sexos. Fibras musculares híbridas fueron observadas en todas las décadas, pero su frecuencia disminuyó significativamente (p <0,001) con el envejecimiento en el masétero. La expresión de miosina neonatal se observo em todas los grupos analizados, aunque su expresión era más frecuente en los músculos maseteros (p = 0,01) y en varones en el temporal (p = 0,025). Se observo una disminución del área de la sección transversal de las fibras rápidas y lentas, y disminución de la densidad capilar al aumentar La edad. Estas alteraciones morfológicas en los músculos masetero y temporal se correlacionan con la disminución de la fuerza asociada al envejecimiento.

Age and gender influence on maximal bite force and masticatory muscles thickness.

The present study aimed investigate the age and gender influence on maximal molar bite force and at outlining the criteria for normal masticatory muscle development in a sample of 177 Brazilian Caucasian dentate individuals aged 7-80 years divided into five age groups: I (7-12 years), II (13-20 years), III (21-40 years), IV (41-60 years), and V (61-80 years). Except for Group V, which comprised nine women and eight men, all groups were equally divided in respect to gender (20 M/20 F). Bite force was recorded with a mouth-adapted 1000N dynamometer and the highest out of three records was regarded as the maximal bite force. The data were submitted to multivariate statistical analysis (SPSS 17.0 p<0.05). Effects of group and gender were found, but no interactions between them. The ANOVA showed significant differences between groups bilaterally. Bonferroni's test showed that group I had significantly lower bite force means at both sides as compared to all groups, except group V. No differences were found between the left and right sides. In all the groups, gender was found to be a significant factor associated with maximal bite force. A global comparison including all the subjects and measures showed that the means of men were approximately 30% higher than those of women. Within-group comparisons yielded similar results in all groups. Muscle thickness was measured with a SonoSite Titan ultrasound tool using a high-resolution real-time 56mm/10MHz linear-array transducer. Three ultrasound images were obtained from the bilateral masseter and temporal muscles at rest and at maximal voluntary contraction. The means of the three measures in each clinical condition were analyzed with multivariate statistical analysis (SPSS 17.0 p<0.05). A gradual increase in thickness of the masseter and temporal muscles was found both at rest and maximal voluntary contraction for groups I to IV, whereas a decrease in muscle thickness was observed in group V. Multivariate analysis showed that in both conditions there was an effect of group and gender. The study of the development of the stomatognathic system in relation to age and gender can provide useful data for the identification of normal and impaired functioning patterns. The results of this study indicate that age and gender are associated with structural and functional alterations in the muscles of the stomatognathic system.

Estudio radiográfico y electromiográfico de los músculos masetero y temporal anterior en individuos con maloclusión tipo II, 1 de angle y controles / Radiographic and electromiographic study of masseter and temporal anterior muscles in subjects with angle II, I malloclusion and controls

El objetivo de este estudio fue comparar la actividad electromiográfica (EMG) de los músculos Masetero (Ms) y Temporal anterior (Ta) de sujetos portadores de maloclusión Angle II, 1 y controles. Se seleccionaron 19 sujetos estudiantes universitarios con características antropométricas similares (edad, peso, talla e IMC). Clínica y radiográficamente se dividieron en dos grupos: Grupo Control (GC) individuos portadores de neutroclusión y Grupo Disto (GD) con individuos portadores de maloclusión Tipo II, 1 de Angle. Se les realizó una electromiografía de superficie (EMG) de acuerdo a la técnica de Ferrario et al. (1993) y se analizaron los datos a partir de Root Mean Square (RMS). A partir de este registro se analizaron la amplitud media de voltaje (mV), la relación Ms/Ta y la distribución de las clases de voltaje, determinadas por los potenciales de acción de unidades motoras (PAUM). De la telerradiografía se analizaron los siguientes datos: ANB, SNA, SNB según Steiner (1992), relación molar, ángulo alfa de inclinación del Ms y brazo de palanca de acuerdo al modelo de Throkcmorton et al. (1980). Se utilizó Test "t" Student para evaluar significancia estadística (p<0,05) entre los grupos. La amplitud de voltaje fue mayor en el GD para todos los músculos estudiados (p<0,05). La relación Ms/Ta fue mayor en el GC. El ángulo alfa fue mayor en GD, también el brazo de palanca. La distribución de PAUM fue mayor en GC (79,0 por ciento), que en GD (57,8 por ciento) (p<0,05). GD presenta mayor amplitud de voltaje que GC, probablemente por presentar menos aferencias inhibitorias periodontales. También GD presenta una menor variedad de PAUM lo que implica que tiene menos reserva funcional que GC.

The of this study is compare the electromiographic activity (EMG) of the Masseter (Ms) and Temporal Anterior (Ta) muscles in subjects with malocclusion Angle II, I and controls. This study involving 19 young adults with similar anthropometric characteristics (Age, weight, hight, BMI). We evaluate clinical and radiographicaly this subject and divided it in to groups: Control Group CG with neutrocclusion and Distal Group (DG) with Angle II, I malocclusion. The both groups was submit a surface EMG according to Ferrario et al. (1993). We used the root mean square (RMS) math operation to calculate the mean voltage amplitude for each muscle. Furthermore we calculate the ratio Ms/Ta and the distribution of voltage class determinate for motor units actions potentials (MUAP). The Rx examination included SNA, SNB and ANB angles according to Steiner (1992), alfa angle and lever arm of Ms according the Throckmorton et al. (1980) mandibular model. The Stundent "t" Test was used to determine whether there were significant differences (p<0.05) between CG and DG parameters. The voltage amplitude was more higher in DG than CG. The ratio Ms/Ta showed protagonism of Ms in CG. The alfa angle and lever arm of Ms were more greater in DG than CG. DG presents a poor number of voltage class (57.8 percent) respect to CG (79.0 percent). DG presents a greater voltage amplitude in relation to CG, probably because the feedback inhibitory periodontal tissue plays an important role. Moreover DG presents a low voltage classes distribution of MUAP that suggest that have minus functional reserve.

Electromyographic evaluation of mandibular biomechanic / Evaluación electromiográfica de la biomecánica mandibular

The study of the craniomandibular biomechanics is related to the system of predominant lever and of the relation between function and mechanically induced deformations. This study has the purpose of evaluating the chewing muscular dynamics in the surface electromyography. Seventeen people of both sex, medium aged about 25, were selected, white skin and presenting Class I of Angle without apparent sign and symptom. The electromiographic data were obtained bilaterally from the masseter muscles, anterior temporal portion at the rest position and isometric position. Medtrace® passive bipolar surface electrodes were used coppled to a pre-amplifier, forming a circuit corresponding to a differential circuit. The registrations of the electric signals were caught by EMG- 800C equipment of Brazil EMG System Ltda with eigth channels, sample frequency of 2 KH and 16 bits resolution, digital filter with a band pass of 20-500 Hz. A comparison was through "t" Student or a Man- Whitney test according to the normality or not of the distribution, respectively. The results have shown important differences between the tasks but without sexual dimorphism. All these results indicate to the electrical activity of the temporal muscle in its anterior portion was bigger than the masseter muscle in rest position and the masseter muscle presented a higher potential of action than the anterior temporal muscle in isometric.

El estudio de la biomecánica craneomandibular se relaciona con el sistema de palanca predominante y la relación entre la función y deformaciones mecánicamente inducidas. Este estudio tuvo el propósito de evaluar la dinámica muscular de la masticación en la superficie electromiográfica en 17 personas de ambos sexos, con edad media de 25 años, de piel blanca y que presentaban clase I de Angle, sin aparentes signos y síntomas. Los datos electromiográficos fueron obtenidos bilateralmente desde los músculos maseteros, la porción anterior del músculo temporal en posición de descanso y en posición isométrica. Electrodos bipolares de superficie pasiva Medtrace ® fueron utilizados acoplados a un pre-amplificador, formando un circuito que corresponde a un circuito diferencial. Los registros de las señales eléctricas fueron capturados por el equipo EMG- 800C de Brazil EMG System Ltda. con 8 canales, frecuencia de muestreo de 2 KH y 16 bits de resolución, un filtro digital con una banda de paso de 20-500 Hz. La comparación fue hecha mediante "t" Student o la prueba Man-Whitney de acuerdo con la normalidad o no, de la distribución, respectivamente. Los resultados mostraron importantes diferencias entre las tareas realizadas, pero sin dimorfismo sexual. Todos estos resultados muestran a la actividad eléctrica del músculo temporal en su porción anterior, mayor que el músculo masetero en posición de reposo, y que el músculo masetero presenta un mayor potencial de acción que la parte anterior del músculo temporal en posición isométrica.

Masticatory muscle thickness, bite force, and occlusal contacts in young children with unilateral posterior crossbite.

Few investigations have evaluated the characteristics of functional and structural malocclusion in young children. Thus, the aim of this study was to assess the ultrasonographic thickness of the masseter and anterior portion of the temporalis muscles, the maximum bite force, and the number of occlusal contacts in children with normal occlusion and unilateral crossbite, in the primary and early mixed dentition. Forty-nine children (26 males and 23 females) was divided into four groups: primary-normal occlusion (PNO), mean (PNO) age 58.67 months; primary-crossbite (PCB), mean age 60.50 months; mixed-normal occlusion (MNO), mean age 72.85 months; and mixed-crossbite (MCB), mean age 71.91 months. Thickness was evaluated with the muscles at rest and during maximal clenching, and comparison was made between the right and left side (normal occlusion), and between the normal and crossbite side (crossbite). The results were analysed using Pearson's correlation, paired and unpaired t-test, and Mann-Whitney ranked sum test. The anterior temporalis thickness at rest was statistically thicker for the crossbite side than the normal side in the MCB group (P = 0.0106). A statistical difference in bite force and the number of occlusal contacts was observed between the MNO and MCB groups, with greater values for the MNO subjects (P < 0.05). Masseter muscle thickness showed a positive correlation with bite force, but the anterior temporalis thickness in the PCB and MCB groups was not related to bite force. Masticatory muscle thickness and bite force did not present a significant correlation with occlusal contacts, weight, or height. It was concluded that functional and anatomical variables differ in the early mixed dentition in the presence of a malocclusion and early diagnosis and treatment planning should be considered.

Esfenomandibular: uma nova entidade anatômica? / Sphenomandibular: a new anatomic entity?

O presente trabalho faz a revisão histórica sobre a presença de uma estrutura muscular como entidade isolada, referida como Esfenomandibular, ou como variação anatômica do músculo Temporal que é observada tendo origem na superfície maxilar do osso Esfenóide e fazendo inserção na Linha Miloidea da Mandíbula

El colgajo del músculo temporal y su aplicación en la cirugía maxilofacial / The temporal muscle flap and its application in maxillofacial surgery

El músculo temporal, craneomandibular, invervado por el nervio trigémino, posee una gran participación en la dinámica mandibular. Su excelente irrigación lo ha convertido en un colgajo de enorme importancia en la cirugía reconstructiva maxilofacial. Esta propiedad se descubre a fines del siglo pasado con los trabajos de Glovine a nivel de órbita, pero se vuelve relevante en los últimos quince años siendo utilizado, este versátil colgajo, en un amplio rango de defectos como: resección de tumores, cirugía de ATM, restauración del contorno facial e incompetencias velofaríngeas entre otros. Mediante el siguiente trabajo se presenta una detallada y seleccionada revisión biliográfica, sobre una base dada por los textos clásicos, con el aporte de nuevos conceptos establecidos en artículos recientemente publicados. Se describen la anatomía quirúrgica del músculo temporal, las indicaciones para la utilización de su colgajo y la variabilidad de opciones que el mismo presenta, realizándose en cadáveres formolizados la reproducción de las técnicas más sobresalientes adjuntas a su correspondiente descripción