Research progress on muscle spindle morphology / 生理学报

Muscle spindle is the key proprioceptor in skeletal muscles and plays important roles in many physiological activities, such as maintaining posture, regulating movement and controlling speed variation. It has significant clinical relevance and is emerging as a promising therapeutic target for the treatment of motor functional impairment and metabolic diseases. In this review, we summarized muscle spindle distribution and the mechanism of mechanical signal transmission, and reviewed the research progress on morphological and structural characteristics of muscle spindles.

Different types of mechanical vibration application on EMG response and strength performance

Abstract Aim: The present study aimed to compare the strength performance and the neuromuscular activity during one maximum repetition test (1RM), and the maximum voluntary isometric contractions (MVIC) performed with whole-body vibration (WBV), local vibration (LV), and no vibration (NV). Methods: The sample consisted of 15 males, experienced in strength training for at least 6 months, which performed all strength tests in the barbell curl exercise across randomized trials on the following conditions: NV, WBV, and LV. During all tests, the normalized root means square values of the electromyographic signals (EMGRMS) of the biceps brachii and brachioradialis were recorded and compared between the conditions. The one-way ANOVAs with repeated measures were used to compare the results of 1RM and MVIC tests and the normalized EMGRMS between the conditions. When necessary, a post hoc Scott-Knott test was used to identify the differences reported in the ANOVAs. The significance level adopted was α < 0.05. Results: The EMGRMS response of the biceps brachii and brachioradialis muscles during the 1RM and MVIC tests presented significantly higher values at LV compared to WBV, and NV (p < 0.001). The 1RM tests, and the MVIC results were similar between conditions (p = 0.9803; p = 0.061, respectively). Conclusion: These results indicate that the application of MV was not sufficient to increase strength performance.

Physiological and neuromuscular responses during the game in female futsal players / Respostas neuromusculares e fisiológicas durante o jogo em atletas de futsal feminino

ABSTRACT This study has evaluated the differences in the physiological and neuromuscular responses in female futsal athletes during a friendly game. Sample comprised six female futsal players (21.8 ± 3.9 years; 57.4 ± 4.1 kg; 159.0 ± 2.7 cm height; 19.0 ± 3.3% body fat and 7.8 ± 1.8 years of practice). Heart rate (HR) was monitored during the whole game. Coutermovement Jump (CMJ), Resistance Explosive Power (REP) lower limb and blood lactate have been evaluated before and after the final of the first and second periods. To compare physiological and neuromuscular variables between the different moments we have used standardized mean difference (SMD), confidence interval (CI = 90%) and the probabilities of differences with clinical relevance. Maximal heart rate (HRmax) was 186.6 ± 10.6 and 185.8 ± 8.3, first and second periods, respectively. There has been a substantial lactate increasing in the moment prior to the start of the game to the final of the first (2.1 ± 0.3 to 6.3 ± 2.3 mmol/L-1, SMD = 5.25 (3.28: 7.21), 100/0/0; most likely) and the second periods (2.1 ± 0.3 to 5.4 ± 1.3 mmol/L-1, SMD = 4.62 (3.19: 6.04), 100/0/0; most likely). Although there has been an increase in blood lactate, the performance of female futsal players was not suppressed during and immediately after a friendly game, suggesting that the neuromuscular system may be restored immediately after the end of the game.

RESUMO O presente estudo testou se existem diferenças, nas respostas fisiológicas e neuromusculares em atletas de futsal durante um jogo amistoso. A amostra foi composta por seis atletas de futsal do sexo feminino (21,8 ± 3,9 anos; 57,4 ± 4,1 kg; 159,0 ± 2,7 cm de altura; 19,0 ± 3,3% gordura corporal e 7,8 ± 1,8 anos de tempo de prática). A frequência cardíaca (FC) foi monitorada durante toda a partida. O salto com contramovimento, resistência de força explosiva de membros inferiores e lactato sanguíneo foram avaliados antes, após o final do primeiro e segundo tempo de jogo. Para comparação das variáveis neuromusculares e fisiológicas entre os diferentes momentos, nós utilizamos as diferenças de médias estandardizadas (DME), intervalo de confiança (IC = 90%) e probabilidades de haver diferenças com relevância clínica. A FC máxima (FCmáx) foi de 186,6 ± 10,6 e 185,8 ± 8,3, primeiro e segundo tempo, respectivamente. Houve um aumento substancial do lactato do momento que antecedeu o início da partida para o final do primeiro (2,1 ± 0,3 para 6,3 ± 2,3 mmol/L-1, DME = 5,25 (3,28: 7,21), 100/0/0; most likely) e segundo tempo (2,1 ± 0,3 para 5,4 ± 1,3 mmol/L-1, DME = 4,62 (3,19: 6,04), 100/0/0; most likely) de partida. Embora tenha ocorrido um aumento do lactato sanguineo, a performance de atletas femininas de futsal não foi suprimida durante e logo após uma partida amistosa, sugerindo que, o sistema neuromuscular possa estar restaurado logo após o término do jogo.

Incidência de lesões em membros inferiores de praticantes profissionais do surf / Incidence of lower limb injuries of professional practitioners of surf

Objetivo ­ Identificar a incidência de lesões em membros inferiores de praticantes profissionais do surf. Métodos ­ A pesquisa foi composta por 38 surfistas profissionais do gênero masculino, com média de idade 32,1 ± 6,6 anos, com tempo de prática 13 ± 6 anos e 5,1 ± 1,3 semanas. Todos responderam a um questionário contendo 14 perguntas abertas e fechadas que foram relacionadas da seguinte forma: categoria do participante, tempo de prática, preparação física antes do surf, tipo de lesão e sua localização, intervenção cirúrgica, tempo de afastamento da modalidade e tempo que se submeteu ao tratamento médico ou fisioterapêutico. Resultados ­ Foram encontradas 48 lesões, sendo oito tipos diferentes, como: entorse de joelho grau I e III, lesão de menisco, ferimento corto-contuso, fratura de hálux, estiramento muscular, queimadura e entorse de tornozelo grau I. Dos 38 participantes, oito apresentaram duas lesões e apenas um apresentou três lesões. Os outros 29 participantes apresentaram apenas uma lesão em membros inferiores, somando um total de 48 lesões encontradas. A entorse de joelho grau III foi a lesão mais encontrada nos participantes 29,2% (N = 14), seguido da lesão de menisco 16,7% (N = 8), dos ferimentos corto-contuso 16,7% (N = 8), das fraturas de Hálux 8,3% (N = 4), dos estiramentos musculares 8,3% (N = 4), das queimaduras 8,3% (N = 4), das entorses de tornozelo grau I 8,3% (N = 4) e das entorses de joelho grau I 4,2% (N = 2). Conclusão ­ Concluímos que a entorse de joelho grau III foi à lesão mais encontrada em membros inferiores nos surfistas profissionais e necessidade de medidas preventivas para evitar futuras lesões.

Objective ­ To identify the incidence of injuries in the lower limbs of practitioners of professional surf. Methods ­ The study was composed of 38 male professional surfers, with mean age 32.1 ± 6.6 years, with practice time 13 ± 6 years and 5.1 ± 1.3 weeks. All participants answered a questionnaire containing 14 questions that were related as follows: category of participant, practice time, physical preparation before the surf, type of injury and its location, surgery, time off and time of medical treatment or physical therapy treatment. Results ­ Forty-eight lesions were found and eight different types, such as first and third degree knee sprain, meniscus injury, sharps injuries, hallux fracture, muscle strain, burning and first degree ankle sprain. Of the 38 participants, eight had two lesions and only one presented three lesions. The other 29 participants showed only one lesion in the lower limbs, with a total of 48 lesions. The third degree knee sprain was the most frequent injury with 29.2% (N = 14), followed by the meniscus injury with 16.7% (N = 8), the sharps injuries with 16.7% (N = 8), fractures of Hallux with 8.3% (N = 4), muscle stretches with 8.3% (N = 4), burns with 8.3% (N = 4), first degree ankle sprain with 8.3% (N = 4) and first degree knee sprains with 4.2% (N = 2). Conclusion ­ We conclude that the third degree knee sprain was the most frequent injury in the lower limbs in professional surfers and the necessity of prevention measures to avoid future lesions.

Changes in muscle spindle afferent discharge activities in rat soleus following hindlimb immobilization / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes in the afferent discharge activities of the sensory nerve endings in muscle spindles of rats with hindlimb immobilization.</p><p><b>METHODS</b>Plaster cast was used immobilize the hindllimbs of rats. Using air-gap technique, the spontaneous discharge of the muscle spindles and its responses to perfusion with succinylcholine (0.05 mg/ml) and suspension in an extended position were observed in isolated muscle spindles from rats with hindlimb immobilization for 3, 7, and 14 days.</p><p><b>RESULTS</b>The muscle spindles of rat soleus showed a sharp decrease in spontaneous discharge frequency (P<0.01) and response to succinylcholine perfusion after 3 days of hindlimb immobilization (P<0.05). Significant changes of the firing rate in an extended position was observed in rats after a 14-day immobilization (P<0.01). The duration of individual spikes was significantly prolonged following hindlimb immobilization (P<0.01).</p><p><b>CONCLUSION</b>Muscle spindle discharges decrease significantly in rats following hindlimb immobilization, which might be related to reduced contractile properties of the muscle spindle.</p>

Method of isolation of intrafusal fibres of muscle spindle in soleus of rats / 生理学报

Capsule restricts the further study on muscle spindle function and the involved mechanism. The aim of this study was to establish the isolation method of intrafusal fibres from the isolated rat muscle spindle. Intrafusal fibres were harvested from muscle spindle of soleus muscle in rats using neutrase-collagenase digestion. A variety of incubation mediums have been tested to find out an appropriate medium of intrafusal fibers in vitro. Trypan blue staining was used to detect cell death, and patch clamp was used to record resting potential. The results showed that the intrafusal fibres incubated with amine acid-saline solution were almost all dead. DMEM could maintain good condition of the fibres, but excess CO2 ventilation would induce cellular swelling or even death. While Leiboviz's 15 (L-15) medium can guarantee 1-2 h of physiological condition of the intrafusal fibres. Coverslips treated with gelatin, polylysine and serum was the better interfaces for the intrafusal fibres to adhere easily, compared with regularly treated coverslip. The resting potential of intrafusal fibres was (-45.3 ± 5.1) mV, consistent with others obtained from in vivo muscle spindle from cats and frogs. These results suggest that the isolation method of the intrafusal fibres has been successfully established in the present study, providing a new approach in better understanding of muscle spindle activities and the involved mechanism.

Relationship between simulated weightlessness-induced muscle spindle change and muscle atrophy / 生理学报

One of the most important and urgent issues in the field of space medicine is to reveal the potential mechanism underlying the disused muscle atrophy during the weightlessness or microgravity environment. It will conduce to find out effective methods for the prevention and treatment of muscle atrophy during a long-term space flight. Increasing data show that muscle spindle discharges are significantly altered following the hindlimb unloading, suggesting a vital role in the progress of muscle atrophy. In the last decades, we have made a series of studies on changes in the morphological structure and function of muscle spindle following simulated weightlessness. This review will discuss our main results and related researches for understanding of muscle spindle activities during microgravity environment, which may provide a theoretic basis for effective prevention and treatment of muscle atrophy induced by weightlessness.

Células satélites e fusos neuromusculares em músculos estriados de ratos desnervados por longo período / Satellite cells and neuromuscular spindles in skeletal muscles in long term denervated rats

O músculo estriado esquelético apresenta em sua constituição células satélites (CS) que se encontram em estado quiescente localizadas entre o sarcolema e a lâmina basal das fibras musculares. As CS podem ser ativadas, diferenciando em mioblastos, contribuindo para regeneração e/ou crescimento do tecido muscular. Os Fusos neuromusculares são mecanorreceptores localizados no interior dos músculos esqueléticos considerados a unidade contrátil reguladora, monitorando a velocidade e duração do alongamento do músculo. Está composto de fibras intrafusais (FIF), circundadas por uma bainha de tecido conjuntivo e encontra-se paralelo às fibras extrafusais. A desnervação promove alterações no músculo esquelético, tanto em CS, quanto nos fusos neuromusculares. Este trabalho analisou quantitativamente as FIF e a proliferação de CS em músculos esquelético de ratos desnervados por longo período. Foram utilizados ratos Wistar. Os animais foram divididos em grupos desnervados e controle. Os músculos Sóleo e Extensor longo dos dedos (EDL) foram desnervados experimentalmente. Após os períodos de 0, 12, 16, 19, 30 e 38 semanas, os músculos foram dissecados, removidos e preparados histológicamente. A porcentagem de CS em músculos imediatamente após desnervação aumenta em relação ao músculo normal e depois decresce em ambos os músculos. Durante o progresso do tempo de desnervação ocorreu um aumento no número de FIF, se comparado com o grupo normal. O número de CS diminui significantemente entre os períodos de desnervação, em ambos os grupos. Nos músculos estudados quanto menor a porcentagem de CS maior é o número de FIF e, aumentando o tempo de desnervação, diminui o número de CS. Em relação às FIF, no grupo controle com o aumento do tempo, o número de fibras não se altera...

The skeletal muscle consists of satellite cells (SC) which are in a quiescent state located between the sarcolemma and basal lamina of the muscle fibers. The SC can get activated, differentiating into myoblasts, contributing to regeneration and/or growth of muscle tissue. The neuromuscular spindles are mechanoreceptors located within the skeletal muscle and are considered as contractile regulatory unit, monitoring the speed and duration of muscle stretching. It is composed of Intrafusal muscle fibers (FIF), surrounded by a sheath and is parallel to extrafusal fibers. Denervation cause changes in skeletal muscles both in the CS and neuromuscular spindles. This study analyzed quantitatively the FIF and the proliferation of CS in rat skeletal muscle, denervated for long period. We used Wistar rats to perform this study. The animals were divided into control and denervated groups. The soleus and extensor digitorum longus (EDL) were denervated experimentally. After periods of 0, 12, 16, 19, 30 and 38 weeks, the muscles were dissected, removed and were prepared for histological analysis. The percentage of SC in muscles immediately after denervation, increases in relation to normal muscle and later decreases in both the groups. During the process of denervation, there was an increase in FIF when compared with normal group. The number of SC reduces significantly between the periods of denervation in both the groups. In the muscles studied, the smaller the percentage of SC, higher is the number of FIF and increase in the duration of denervation, reduces the number of SC. As for FIF, with the increase in time in control group, the number of fibres was unaltered...

Células satélites e fusos neuromusculares em músculos estriados de ratos desnervados por longo período / Satellite cells and neuromuscular spindles in skeletal muscles in long term denervated rats

O músculo estriado esquelético apresenta em sua constituição células satélites (CS) que se encontram em estado quiescente localizadas entre o sarcolema e a lâmina basal das fibras musculares. As CS podem ser ativadas, diferenciando em mioblastos, contribuindo para regeneração e/ou crescimento do tecido muscular. Os Fusos neuromusculares são mecanorreceptores localizados no interior dos músculos esqueléticos considerados a unidade contrátil reguladora, monitorando a velocidade e duração do alongamento do músculo. Está composto de fibras intrafusais (FIF), circundadas por uma bainha de tecido conjuntivo e encontra-se paralelo às fibras extrafusais. A desnervação promove alterações no músculo esquelético, tanto em CS, quanto nos fusos neuromusculares. Este trabalho analisou quantitativamente as FIF e a proliferação de CS em músculos esquelético de ratos desnervados por longo período. Foram utilizados ratos Wistar. Os animais foram divididos em grupos desnervados e controle. Os músculos Sóleo e Extensor longo dos dedos (EDL) foram desnervados experimentalmente. Após os períodos de 0, 12, 16, 19, 30 e 38 semanas, os músculos foram dissecados, removidos e preparados histológicamente. A porcentagem de CS em músculos imediatamente após desnervação aumenta em relação ao músculo normal e depois decresce em ambos os músculos. Durante o progresso do tempo de desnervação ocorreu um aumento no número de FIF, se comparado com o grupo normal. O número de CS diminui significantemente entre os períodos de desnervação, em ambos os grupos. Nos músculos estudados quanto menor a porcentagem de CS maior é o número de FIF e, aumentando o tempo de desnervação, diminui o número de CS. Em relação às FIF, no grupo controle com o aumento do tempo, o número de fibras não se altera...

The skeletal muscle consists of satellite cells (SC) which are in a quiescent state located between the sarcolemma and basal lamina of the muscle fibers. The SC can get activated, differentiating into myoblasts, contributing to regeneration and/or growth of muscle tissue. The neuromuscular spindles are mechanoreceptors located within the skeletal muscle and are considered as contractile regulatory unit, monitoring the speed and duration of muscle stretching. It is composed of Intrafusal muscle fibers (FIF), surrounded by a sheath and is parallel to extrafusal fibers. Denervation cause changes in skeletal muscles both in the CS and neuromuscular spindles. This study analyzed quantitatively the FIF and the proliferation of CS in rat skeletal muscle, denervated for long period. We used Wistar rats to perform this study. The animals were divided into control and denervated groups. The soleus and extensor digitorum longus (EDL) were denervated experimentally. After periods of 0, 12, 16, 19, 30 and 38 weeks, the muscles were dissected, removed and were prepared for histological analysis. The percentage of SC in muscles immediately after denervation, increases in relation to normal muscle and later decreases in both the groups. During the process of denervation, there was an increase in FIF when compared with normal group. The number of SC reduces significantly between the periods of denervation in both the groups. In the muscles studied, the smaller the percentage of SC, higher is the number of FIF and increase in the duration of denervation, reduces the number of SC. As for FIF, with the increase in time in control group, the number of fibres was unaltered...

Effects of 100 Hz sinusoidal vibration on H reflex and M wave in rat soleus muscle following immobilization / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the effects of 100 Hz sinusoidal vibration on H reflex and M wave in rat soleus muscle following immobilization.</p><p><b>METHODS</b>The immobilization of rat soleus muscle was induced as a disuse muscle model, and 100 Hz sinusoidal vibration was generated by a vibrator and applied to the immobilized soleus muscle, then the changes of H reflex and M wave in muscle were observed after 14 d.</p><p><b>RESULTS</b>Compared to control, after 14 d of immobilization M(max) in soleus muscle decreased (P<0.01), stimulus threshold and S(max) increased (P<0.01); Hmax and H(max)/M(max) decreased (P<0.05, S(max) increased (P<0.05). Compared to immobilized soleus muscle, after 14 d of immobilization with 100 Hz sinusoidal vibration, the M(max) increased(P<0.01), stimulus threshold and S(Mmax) decreased (P<0.05), H(max) (P<0.01) increased and H(max)/M(max) increased (P<0.05).</p><p><b>CONCLUSION</b>100 Hz sinusoidal vibration plays a significant antagonist role against the changes in H reflex and M wave in rat soleus muscle following immobilization.</p>

Decreased neurotrophin-3 expression of intrafusal muscle fibers in rat soleus muscles under simulated weightlessness / 生理学报

The present study aimed to study the changes of neurotrophin-3 (NT-3) expression of intrafusal muscle fibers in rat soleus muscles under simulated weightlessness. The tail-suspension (SUS) rat model was used to simulate weightlessness. Forty mature female Sprague-Dawley rats were randomly assigned to ambulatory control (CON), 3-day SUS, 7-day SUS, 14-day SUS and 21-day SUS groups. Immunohistochemistry ABC staining method and enzyme linked immunosorbent assay (ELISA) were used to detect the NT-3 expression of intrafusal muscle fibers in rat soleus muscles. The results from the immunohistochemistry staining technique showed that the extrafusal muscle fibers did not exhibit the NT-3-like immunoreactivity, and NT-3-like immunoreactivity was mainly expressed in nuclear bag 1 and nuclear bag 2 fibers of the muscle spindles. The ELISA results showed that the expression quantity of NT-3 in rat soleus muscles in control, 3-day SUS, 7-day SUS, 14-day SUS and 21-day SUS groups were (14.23±1.65), (14.11±1.53), (13.09±1.47), (12.45±1.51) and (9.85±1.52) pg/mg of tissue respectively. Compared to the control group, the expression quantity of NT-3 was significantly decreased after 14 days of SUS (P<0.05). After 21 days of SUS, the NT-3 expression was further reduced (P<0.01). These results suggest that simulated weightlessness induces an obvious decrease in the NT-3 expression level of intrafusal fibers in rat soleus muscles. Accompanying the simulated weightlessness extension, NT-3 expression in rat soleus muscle spindles is progressively decreased. These changes may contribute to the proprioceptive adaptations to microgravity.

Electrophysiological characteristics of the isolated muscle spindle in rats / 生理学报

The aim of this study was to observe the electrophysiological characteristics of the isolated rat muscle spindle. The muscle spindle was isolated from rat soleus and the afferent discharge of the isolated muscle spindle was recorded by air-gap technique. In the basic physiological salt solution, the spontaneous impulses of muscle spindle were at a lower level with irregular intervals. The mean frequency of afferents was (51.78 ± 25.63) impulses/1 000 s (n = 13). The muscle spindle afferents were significantly increased and maintained over time by the addition of certain amino acids during the observation. The number of the action potential recorded per 1 000 s was 200-1 000 [mean: (687.62 ± 312.56) impulses/1 000 s, n = 17]. In addition to the typical propagated action potential, a large number of abortive spikes were observed. The results indicate that the activities of isolated muscle spindles in rats can be well maintained by the addition of certain amino acids. The results initially establish and provide the possibility for further research conducted in isolated rat muscle spindles.

Demanda do sistema nervoso central no controle da postura ereta humana: um modelo em malha aberta e malha fechada / Central nervous system demand on human erect posture control: an open and closed loop model

A maneira como os seres humanos controlam o equilíbrio na postura ereta não é ainda totalmente compreendida e como o sistema nervoso central controla e mantém a postura ereta quieta ainda é alvo de discussão. Nos modelos de controle postural existentes observa-se uma variação contínua do sinal do elemento final de controle, o que certamente pode comprometer a integridade do mesmo e provocar grande demanda de processamento. Visando sua preservação, uma solução seria aumentar o período de comutação, fazendo com que o elemento final de controle atue somente quando o balanço postural afastar-se consideravelmente do sinal de referência. Uma forma de implementar essa solução é empregar controladores que possuam uma zona morta ou intervalo diferencial em torno do valor de referência, definida por um limite superior e um limite inferior. O presente trabalho teve como objetivo investigar se modelos de controladores com intervalo diferencial são adequados para representar o controle da postura ereta. Para tanto, foi implementado um modelo de pêndulo simples para representar a dinâmica do sistema músculo-esquelético humano no plano sagital, com o sistema de controle neural enviando comandos para gerar um torque corretivo que resiste ao desvio da posição do corpo. Implementou-se um modelo de controle por feedback, onde o desvio da posição de referência é percebido e corrigido por um controlador PID que se assemelha a parâmetros neuromusculares, acrescido das características passivas visco-elásticas do músculo. O modelo foi simulado para limites superiores e inferiores de até 0,5º do sinal de referência, onde neste intervalo o sistema age como malha aberta. Observou-se que a opção do controlador com intervalo diferencial piora a qualidade do controle, mas solicita menos o elemento final de controle.

The necessary demand to stabilize the human posture is associated with the way Central Nervous System controls and keeps the quiet erect posture. In existing posture control models, a continuous variation of final element control signal is observed, which will certainly wear the controller. A solution to preserve it would be the increase in commutation period, causing the final control element to act only when postural balance is distantly related to reference signal. A way to implement this solution is to use controllers with a differential gap around the reference signal, defined by a superior and inferior limit. A simple pendulum model is used to represent the dynamics of the human musculo skeletal system on sagittal plane, with neural control system sending instructions in order to produce a corrective torque that stand up to body position deviation. A feedback control model was carried out, where there reference position deviation is perceived and corrected by a PID controller, that resembles neuromuscular parameters, added to passive viscous-elastic properties of the muscle. A model for superior and inferior limits up to 0.5° of reference signal was simulated. In this gap the system acted as an open loop, therefore without the correction of reference signal. It was observed that the option of controller with differential gap worsens the quality of control, but demands less the final element of control.

The influence of gender and bruxism on human minimum interdental threshold ability

OBJECTIVE: To evaluate the influence of gender and bruxism on the ability to discriminate minimum interdental threshold. MATERIAL AND METHODS: One hundred and fifteen individuals, representing both genders, bruxers and non-bruxers, with a mean age of 23.64 years, were selected for this study. For group allocation, every individual was subjected to a specific physical examination to detect bruxism (performed by three different examiners). Evaluation of the ability to discriminate minimum interdental threshold was performed using industrialized 0.010 mm-, 0.024 mm-, 0.030 mm-, 0.050 mm-, 0.080 mm- and 0.094 mm-thick aluminum foils that were placed between upper and lower premolars. Data were analyzed statistically by multiple linear regression analysis at 5% significance level. RESULTS: Neither gender nor bruxism influenced the ability to discriminate minimum interdental threshold (p>0.05). CONCLUSIONS: Gender and the presence of bruxism do not play a role in the minimum interdental threshold.

Distribution of the muscle spindles in human masticatory muscles / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the characteristics in the topographic distribution of the muscle spindles in human masticatory muscles.</p><p><b>METHODS</b>The muscle spindles of the masticatory muscles on both sides of 3 human corpses fixed in formalin for more than 1 year were observed histologically and analyzed quantitatively using an image analysis system.</p><p><b>RESULTS</b>The mean muscle spindle density was 32.11/g in the masseter, significantly higher in the deep muscular fibers (70.76/g) with high proportion of spindle complexes than in the superficial layers of the muscle belly (P<0.05). The mean spindle density in the temporalis was 5.44/g, higher in the anterior portion (7.44/g) than in the posterior portion (3.78/g, P<0.01). The medial pterygoid had a mean spindle density of 4.43/g.</p><p><b>CONCLUSION</b>These results indicate a heterogeneous distribution of muscle spindles in the masticatory muscles with different morphologies or in different portions of the same muscle, depending on muscle fiber type and muscular architecture.</p>

Análise da excreção urinária de hidroxiprolina e do nível de dor em sujeitos com lombalgia após alongamento na hidrocinesioterapia / Urinary excretion of hydroxyproline analysis and pain in subjects with low back pain after stretching in hydrotherapy

Hidroxiprolina (HP) e da lombalgia, através de um programa de hidrocinesioterapia, enfatizando o alongamento em água aquecida a 34°C. Participaram do estudo 8 policiais militares do Estado do Rio de Janeiro, do sexo masculino, entre 25 e 45 anos; todos com sintomatologia de lombalgia de causa idiopática e com encaminhamento médico à hidrocinesioterapia. O estudo realizou-se no Centro de Fisiatria e Reabilitação da Polícia Militar do Rio de Janeiro. A piscina onde foi realizada a intervenção media 12 x 6 m, 1,20 de profundidade, com a água a 34°C. A intervenção consistiu de dez sessões de hidrocinesioterapia, duas vezes por semana. Durante cada sessão de 50 minutos, foram realizados os seguintes exercícios: 5 minutos de aquecimento – caminhada; 40 minutos de exercícios específicos – bicicleta em suspensão com flutuador na região axilar; e 5 minutos de alongamento de paravertebrais, bíceps femural, glúteo médio e máximo, tensor da fascia lata, quadrado lombar e tríceps sural. A dor lombar foi mensurada através da escala CR-10 de Borg, antes e após as dez sessões do tratamento, e o nível de HP através do protocolo HPROLI 2h. Os resultados demonstraram que os níveis de HP, antes e depois do tratamento, foram iguais a 53,3 ± 22,6 e 31,6 ± 11,3 mg/d, respectivamente. O teste t de Student apresentou valor para t igual a 3,93, para p = 0,008 demonstrando haver diferença significativa entre HP antes e após a hidrocinesioterapia. Os níveis de dor mensurados, antes e depois do tratamento, foram iguais a 5 ± 2 e 2 ± 1, respectivamente. O teste de Wilcoxon apresentou valor para Z igual a 2,20, para p = 0,03 demonstrando haver diferença significativa entre estes níveis antes e após a hidrocinesioterapia. Conclui-se que o método de alongamento utilizado na hidrocinesioterapia, em pacientes com lombalgia, promoveu redução dos níveis de HP e dor lombar.

The aim of this study was to measure excretion levels of hidroxyproline (HP) in subjects with low back pain through a hydrotherapy program, emphasizing the stretching in warm water 34°C. The subjects of the study were 8 military policemen of the state of Rio de Janeiro, between 25 and 45 years old, all of them with idiopathic low back pain and recommendation to practice hydrotherapy. The intervention was in the Physical Medicine and Rehabilitation Center of Military Policy of Rio de Janeiro. The swimming pool measured 12 x 6 m, with 1,20 of depth and water temperature of 34°C. The intervention consisted of ten sessions of hydrotherapy, twice a week. The exercise program, with 50 minutes each session, was as follows: 5 minutes of walking, 40 minutes of specific exercises – float suspension bicycle in the axillar area and 5 minutes of stretching of paravertebral, biceps femuralis, gluteus maximus and medius, tensor faciae latae muscle, lumbar quadrate and triceps surae. The low back pain was measured by Borg scale CR-10 before the 1st session of the intervention and after the last one, as well as HP level using HPROLI 2h protocol. The results showed that HP levels before and after treatment was 53.3 ± 22.6 and 31.6 ± 11.3 mg/d, respectively. The t Student test showed t 3.93, and for p = 0.008 showing a significant difference between HP levels before and after hydrotherapy. The low back pain before and after treatment was 5 ± 2 and 2 ± 1, respectively. The Wilconxon test showed Z 2,20 and for p = 0,03 and with significant difference between these levels before and after hydrotherapy. One concludes that the stretching method used by hydrotherapy in patients with low back pain promoted reduction in HP levels and low back pain.

Tono muscular / Muscle tone

O tono muscular é relativamente fácil de ser examinado e difícil de ser avaliado, pois se trata de matéria de julgamento, e que somente é aprendido por exames repetidos. As alterações do tono podem ocorrer na presença de doenças que envolvam qualquer porção de sistema motor. Nesta revisão o autor faz um apanhado geral sobre a avaliação semiológica do tono muscular e suas diversas formas de apresentação, além de tecer comentários a respeito do mecanismo e modo de atuação do sistema fusimotor.

Progenie / Class III malocclusion

Se realiza una revisión de las distintas clases de progenies de acuerdo a su etiología y desarrollo. Se incluye una descripción de los posibles tratamientos según los casos. Las maloclusiones Clase III se caracterizan por una posición mesial de la arcada dentaria mandibular respecto a la maxilar, produciendo una mordida cruzada anterior. Con grecuencia estos pacientes presentan una maloclusión dentoesquelética, resultado de una deficiencia maxilar, prognatismo mandibular o una combinación de ambos. Su etiologá es poligénica, donde interactúa la genética y los factores ambientales. Esta maloclusión comrpomete mucho la estética facial, lo que hace que se busque frecuentemente atención temprana

One-minute bouts of passive stretching after immobilization increase sarcomerogenesis in rat soleus muscle

Although the effect of stretching on skeletal muscle has been investigated, the mechanical influence of short bouts of passive stretch, commonly used in rehabilitation therapy to recover skeletal muscle length after immobilization, has not been studied in detail. The hypothesis of this study was that one-minute bouts of muscle stretching applied after immobilization would induce sarcomerogenesis in muscle fibers. To assess this hypothesis, sessions of passive stretching (10 stretches of 1 min each with 30 s rests between stretches) were applied daily or three times a week to the left soleus muscle after immobilization in the shortened position. Eighteen rats were immobilized for four weeks and divided into three groups: 1) after immobilization, the rats remained free for three weeks, 2) the soleus muscle was stretched daily for three weeks, and 3) the soleus muscle was stretched three times a week for three weeks. A control group was run in parallel. The crosssectional area of the soleus muscle fibers and the serial number and length of sarcomeres were measured. Both of the stretch protocols increased the serial number of sarcomeres, but not the cross-sectional area of the muscle fibers. In conclusion, short bouts of passive stretching alter the muscle fiber tropism and induce serial sarcomerogenesis after immobilization.

Stereology investigation of muscle spindles in human masseter and temporalis muscle / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To find out the characteristic topographic distribution of the muscle spindles in human masseter and temporal muscle, and to clarify the neurobiology roles of masticatory muscles during chew and adjusting mandibular position.</p><p><b>METHODS</b>The muscle spindles of masseter and temporal muscle on both sides of 5 human corpses fixed in formalin for more than 1 year were observed and quantitatively analyzed by picture analysis equipment.</p><p><b>RESULTS</b>The muscle spindles were maldistributed and spindles were commonly clustered in some individual portions, and the muscle spindle figures were diversiform, which were predominantly composed of the spindle simple and spindle complexes. The masseter spindles of the deep portion were obviously more than that of the superficial. Spindles of temporal muscle were concentrated in the anterior approach to the coracoid.</p><p><b>CONCLUSION</b>The distribution of muscle spindles in the masseter and temporal muscle is heterogeneous, spindle density in the deep portion of masseter and the anterior of temporolis muscle is greater than others. The deep of masseter and the anterior of temporal muscle play an important part in maintaining mandibular position and balance.</p>