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Results for “Temporal Muscle”

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At least 1,477 records · Page 82Linked to original sources
PubMed1996

Horizontal transposition of the vertical rectus muscles for cyclotropia.

PURPOSE: We studied the effect of horizontal transposition of the vertical rectus muscles on incyclotropia and excyclotropia in terms of the amount of correction obtained and the stability of the outcome. METHOD: Preoperative measurements for cyclotropia were compared in 11 patients with measurements during the immediate postoperative period and last follow-up. Excyclotropia was treated with nasal transposition of the inferior rectus muscle and incyclotropia with nasal transposition of the superior rectus muscle, to which we added temporal transposition to the inferior rectus muscle in one patient to enhance the effect. RESULTS: Fusion in all gaze positions was restored in six patients and functional improvement occurred in five. The average effect of horizontal transposition of one vertical rectus muscle for cyclotropia was a correction of 7 degrees in primary position and of 11 degrees in depression. This effect remained stable after a mean follow-up of 17 months, and additional improvement occurred in one patient. One patient developed a hypertropia, eliminated by an additional operation, in the treated eye. CONCLUSIONS: For excyclotropia, nasal transposition of the inferior rectus muscle is a viable alternative to lateral and anterior transposition of the anterior portion of the superior oblique tendon. It becomes the procedure of choice when surgery on the superior oblique tendon is precluded, either by the tendon's congenital absence or by previous surgery on the tendon. Nasal transposition of the superior rectus muscle or temporal transposition of the inferior rectus muscle is ideally suited for incyclotropia. No comparably effective operation exists.

Adult↗
PubMed1998

Effect of muscle relaxation splint therapy on the electromyographic activities of masseter and anterior temporalis muscles.

The purpose of this study was to compare the effectiveness of splint therapy on the electromyographic activity of masticatory muscles (anterior temporalis and masseter) before and after the application of a muscle relaxation splint. Electromyography recordings from the masseter and anterior temporalis muscles were analyzed quantitatively during maximal biting in the intercuspal position both before and after treatment without a splint. Fourteen patients whose chief complaint was masticatory muscle pain were selected for the study. After the initial evaluations muscle relaxation splints were applied, and the patients were instructed to use the splints for 6 weeks. Surface electromyographic recordings were taken from each patient before the beginning of clinical therapy and after 6 weeks of wearing the splints. The data obtained were analyzed through paired sample t tests and Wilcoxon's signed rank tests. The results of the study were as follows: (1) the electromyographic activity of the two muscles during maximal biting was not markedly changed after the muscle relaxation splint was used; and (2) the changes observed in electromyographic activity of the involved and noninvolved sides were insignificant as well.

Adult↗
PubMed1999

Quantitative analysis of masseter and temporalis EMGs: a comparison of anterior guided versus balanced occlusal concepts in patients wearing complete dentures.

The lack of easily measurable, objective physiological activity parameters of the masseter and temporalis muscle during jaw movements in humans has led to the consideration to revise data of surface electromyographies (EMGs) by applying a computerized quantification method. The aim of this follow-up analysis was to get quantitative data out of EMG-records of an earlier study. These records were obtained with two different splints, splint 1 providing an anterior front-canine guidance and splint 2 providing bilateral balanced occlusion. Utilizing a computer aided integration method led to numeric results which statistically proves the prediction of the previous investigation. Applying the integration method, the EMG raw signal was transformed into area-values which enabled a statistical work up of the data. Wilcoxon test statistics shows a significant (P<0.05) lower muscle activity in patients wearing dentures providing anterior front-canine guidance compared to those with balanced occlusion. It is concluded that the neuromuscular activity of the elevator muscles is highly reproducible and that the neuromuscular function is similar in edentulous subjects to that found in people with natural teeth. Furthermore, the study statistically proves earlier visual data that all those subjects, whose muscle activities were observed with anterior guidance (splint 1) compared to bilateral balanced occlusion (splint 2) showed significantly lower values with regard to subjects wearing splint 2.

Centric Relation↗
PubMed1994

Screening for temporomandibular disorders in dental practice.

A simple screening procedure to determine evidence of a temporomandibular disorder (TMD) in a patient is presented. The current view is that dentists are responsible for the recognition and management of these disorders. The dentist should therefore perform a TMD screening examination on every patient and document the patient's functional status. If this is not known then it is impossible to discuss with the patient the possible implications of proposed dental treatment which could potentially worsen a pre-existing TMD. Unless functional status is documented and informed consent obtained from the patient prior to proceeding with dental treatment, the dentist may be held liable should TMD problems develop during or after the treatment.

Adolescent↗
PubMed1980

Electromyograms are repeatable: precautions and limitations.

Electromyograms recorded by bipolar, fine wire electrodes placed into anatomically equivalent sites in skeletal muscles of vertebrates are repeatable when the animals use the muscles in a similar way. Repeatability applies to the number of spikes recorded from a given site and to their average amplitude as well as to the root-mean-square value, though the values obtained for these descriptors differ among muscles, and perhaps fascicles, of particular animals even when the animals are performing equivalent actions. Tests suggest that these results are not affected by the nature of most kinds of recording equipment. Also, substantial differences in electrode tip configuration and wire diameter induce relatively minor, less than 8 percent, differences in electrode resistance and impedance. Doubling the length of the fine wire leads produces less than an 8 percent (15 percent when the length is tripled) effect; however, the effect of electrode material may be as much as 85 percent in resistance and 20 percent in impedance. Reports of nonreproducibility or variability of electromyograms apparently result mainly from anatomically inexact placement into physiologically and histochemically different fascicles of compound muscles, from recordings of muscles that are active at very low levels, and perhaps from comparison among recordings of muscles that really differ in their activity level.

Action Potentials↗
PubMed2001

Effects of post-natal serotonin levels on craniofacial complex.

Although the role of serotonin (5-hydroxytryptamine or 5-HT) in pre-natal craniofacial growth and development has been studied, no research has been done on the effects of serotonin on post-natal craniofacial growth and development. The following experimental question was tested: What effect does increasing in vivo serotonin levels adjacent to trigeminal motoneurons have on post-natal craniofacial structures in young, actively growing rats? Forty male Sprague-Dawley rats were divided into 4 experimental groups (10% serotonin microspheres, 15% serotonin microspheres, blank microspheres, sham surgeries) and underwent stereotactic neurosurgery at post-natal day 35; 5 rats of each group were killed at 14 and 21 post-surgical days for data collection. Statistical analyses by mixed-model, 4 x 2 repeated-measures ANOVA, and post hoc Fisher LSD tests revealed significant (P < or = 0.05, 0.01) differences between groups and sides for muscle weight, cranial dimension, and TMJ dimension data. Data described here indicate that significant alterations of post-natal craniofacial structures can be caused by altered in vivo levels of serotonin adjacent to trigeminal motoneurons.

Analysis of Variance↗
PubMed1989

[Electromyographic study on the effects of head position to head and neck muscles].

The purpose of this study is to reveal the relationship between the head position, and the neck and head muscles. At 4 head positions, the activities of masseter, anterior temporal, anterior digastric, sternocleidomastoid and trapezius muscle of ten normal subjects standing straight were investigated electromyographically with surface electrodes during voluntary maximal clenching in centric occlusion. Head positions were right tilting, left tilting, up-right and natural head position. The results obtained were as follows; 1. During head tilting, the activities of anterior digastric and sternocleidomastoid muscle on the tilting side were increased, the activities of masseter and trapezius muscle on the opposite side of the tilting side were increased, the activity of the anterior temporal muscle did not vary from the activity during up-right head position. 2. During natural head position, only the activity of sternocleidomastoid muscle on the natural tilting side was increased.

Electromyography↗
PubMed1993

Task-related behaviour of motor units in the human temporalis muscle.

Muscle activity patterns in some complex human jaw muscles appear to be task sensitive. However, it is presently uncertain how changes in motor task affect motor unit (MU) behaviour in the human temporalis muscle. In this study, activity was recorded from 40 MUs in the anterior region of the muscle. The lowest sustainable firing frequency (LSFF) was reached by slow increases and decreases in firing rate, then firing was maintained at the lowest possible rate without significant pauses. An array of consecutive interspike intervals (ISI) were sampled digitally and used to measure the LSFF for each task associated with the MU. In a controlled paradigm, MU reflex inhibition was measured during the performance of different tasks. Single electrical pulses of non-noxious intensity were delivered to the gingiva near the maxillary canine tooth. During continuous MU firing at a controlled firing frequency of 10 Hz, series of pulses were delivered with increasing delays, after preselected spikes. The MUs fired continuously during the performance of 1-4 postural and tooth-contact tasks. There were significant differences in LSFFs between tasks in those MUs associated with multiple tasks. In the reflex study, all MUs were inhibited, but the magnitude of the inhibition was highly task dependent. Thus, both LSFF and reflex inhibition of temporalis MUs appear to vary with the motor task and are sensitive to the position of the jaw and the direction and location of tooth contact along the tooth row. This behaviour most likely reflects task-related changes in output from orofacial and muscle afferents.

Action Potentials↗
PubMed1992

Temporalis muscle transfer in the treatment of the severely contracted socket.

The treatment of severely contracted sockets represents one of the most difficult situations in ophthalmic plastic and reconstructive surgery. In particular, the treatment of the postirradiated socket has been considered "hopeless surgery." In recent years a modified approach to this problem has been tried, in which the use of the temporalis muscle provided a well-vascularized bed for delayed reconstructions.

Contracture↗
PubMed1999

Modulation of jaw reflexes by remote noxious stimulation and mental state: possible association with psychological measurements of mental stress and occupation.

Combined electrophysiological and psychophysical experiments were performed on 15 human subjects to investigate the possible effects of perceived stress or mental occupation on jaw reflexes. Electromyographic recordings were made from the masseter and anterior temporalis muscles, of the series of excitatory and inhibitory reflexes evoked by tapping on an upper incisor tooth. The reflexes were modified by application of painful cold (3 degrees C) stimuli to the subject's hand (remote noxious stimulation) or by the subject undertaking mental exercises (the 17 times table). The resulting changes in the reflexes usually involved transient increases in EMG activity around the interfaces between successive inhibitory and excitatory responses. Both the remote noxious stimuli and the mental exercises usually produced increases in both stress and mental occupation as assessed using visual analogue scales. However, correlations between these psychological effects and the effects on the reflexes were generally weak or absent. We conclude that the modulation of jaw reflexes by remote noxious stimuli or mental activity is not likely to be dependent on an individual's conscious awareness of a change in mental state. On the other hand, data from a related study suggest that the effects on the reflex may be more closely related to the autonomic responses to stress.

Adult↗
PubMed2002

Voluntary and reflex control of the human temporalis muscle.

Electromyographic recordings (EMGs) were made in 10 human subjects from the anterior and posterior parts of the temporalis muscle using skin surface electrodes. The activities produced by voluntary maximal clenching tasks and the reflex responses to electrical stimulation of the muco-gingival junction were studied. In most subjects, maximum activity in both parts of the muscle occurred when clenching in the intercuspal position (anterior temporalis: 7 of 10 subjects; posterior temporalis: 9 of 10 subjects). Clenching maximally in the retruded position usually resulted in less activity; when this activity was expressed as a percentage of the maximum achieved by each subject for that part of the muscle, the median values were: anterior temporalis, 68% and posterior temporalis, 79%. Clenching in the protruded position produced little or no activity (median values: anterior temporalis, 3%; posterior temporalis, 5%). There were no significant differences between the EMG activities of the anterior and posterior parts of the muscle during these tasks when the activities were normalized to the maximum achieved in each part of the muscle. Application of electrical stimuli at the muco-gingival junction (upper incisor region) produced reflex inhibitions and excitations in both parts of the muscle. There were no significant differences in the thresholds of these reflexes between the anterior and posterior parts of the muscle. Furthermore, there was little difference between the two parts of the muscle in terms of the latencies, durations and magnitudes of the responses. Thus the results of the study suggest that there are similar neural control mechanisms for the anterior and posterior parts of the temporalis muscle despite the common view that these parts of the muscle have different functions.

Adult↗
PubMed1997

Short-term reproducibility of pressure pain thresholds in masseter and temporalis muscles of symptom-free subjects.

Pressure pain thresholds (PPTs) of the bilateral masseter and temporalis muscles were assessed over a single day and in between 2 days with the aid of an electronic algometer in 11 males and 11 females. Using a mixed model approach, covariance results were controlled for confounding of gender, day, time of the day and the within-session replications of the measurements. For every jaw muscle, the first PPT measurement of a session was markedly higher than the last one of that same session. Except for the right temporalis muscles, no significant systematic PPT differences could be observed between male and female subjects. The differences between morning and afternoon sessions were not significant for any of the muscles tested. Although the PPTs measured on the 1st day were systematically lower than those on the 2nd day for the left masseter and temporalis muscles, no significant difference between the time of the day could be observed when the values of the different muscles were grouped within a subject. Analysis of variance showed that the variability induced by the day or the time of the day was similar to the variability of the measurement itself. The inter-individual variability of PPTs was 2.3 to 9 x higher than the variability observed between trials, sessions or days. The results indicate that the PPT measurement will not be systematically influenced by the time of registration (morning/afternoon) or inbetween consecutive days. In addition, the important inter-individual differences favor the use of longitudinal within-subject studies.

Adult↗
PubMed2002

Task-dependence of activity/ bite-force relations and its impact on estimation of chewing force from EMG.

Estimation of chewing force from electromyograms (EMGs) calibrated in isometric biting yielded strikingly high force values. We tested the hypothesis that EMG-based force predictions are excessive because of differing activity/bite-force relations in mastication and isometric biting. In nine patients, unilateral bite forces and EMGs of 4 elevator muscles were recorded during chewing and isometric clenching on a bite-fork. We estimated chewing force by substituting chewing EMGs of each muscle into isometric activity/bite-force regressions. The estimates were compared with actual chewing forces recorded by intra-oral transducers. In all muscles except the balancing-side masseter, the activity/bite-force ratio was significantly higher in chewing than in isometric biting. The actual mean chewing force amounted to 220 N, while EMG-based estimates ranged from 273 to 475 N, depending on the muscle used for estimation. The results indicate that different activity/force characteristics in dynamic and isometric biting can cause overestimation when chewing force is predicted from masticatory EMGs.

Algorithms↗
PubMed1998

Giant intracranial and extracranial cavernous malformation. Case report.

Massive enlargement of an extracerebral cavernous malformation and extension across tissue planes is very uncommon. The authors present the case of a 49-year-old woman with a giant cavernous malformation in the left frontotemporal area. It progressively enlarged during several decades, extended through the calvaria to the extradural space, and was surgically treated. The lesion may have originated in the soft tissue or the skull. The locations of cavernous malformations in various parts of the body are reviewed and their mechanisms of growth are discussed. Surgical excision is the treatment of choice.

Disease Progression↗