Relationship between the angle of the coronoid process of the mandible and the electromyographic activity of the temporal muscle in skeletal Class I and III individuals.

The aim of the present study was to verify the relationship between the angle of the coronoid process of the mandible in the latero-lateral direction and electromyographic activity of the anterior part of the temporal muscle in skeletal Class I and III individuals. Forty-five volunteers were assessed subdivided into two groups, according to angle ANB, in Class I and III. Two radiographic examinations were performed, one lateral cephalogram to measure angle ANB and one frontal cephalogram to measure the angle of the coronoid process. The electromyographic examination of the volunteers' temporal muscles was performed. Statistical analysis of the data showed that the relationship between the angle of the coronoid process and the skeletal class was negative for both classes analysed. The relationship between electromyographic activity of the temporal muscle and angle of the coronoid process was negative for Class I individuals. In the Class III group, smaller angles of the coronoid process were related to higher values of electromyographic activity of the temporal muscle. There was no statistically significant difference between the electromyographic activity of the temporal muscle in skeletal Class I and III individuals. Based on the results obtained, it was concluded that there was no influence of the skeletal classes analysed on the angle of the coronoid; the angle of the coronoid process may be influenced by the electromyographic activity of the temporal muscle in the Class III group; the electromyographic activity of the temporal muscle is not influenced by the skeletal class in Class III individuals.

Electromyographic study of stomatognathic system muscles during chewing of different materials.

OBJECTIVE: The aim of this study was to compare the behavior of the major chewing muscles (anterior temporalis, masseter and suprahyoid muscles) by using two commercial chewing gums (A and B) and two insipid materials (cotton ball and Parafilm M) through analysis of electromyographic signals. METHOD: Ten female young adult subjects, aged from 18 to 27 years, with normal occlusion and no history of craniomandibular disorder were studied The masticatory activity was performed with the subjects comfortably sat so that the Frankfurt plane was parallel to the floor. Electromyographic exams were carried out using bipolar surface passive mini-electrodes positioned on the anterior temporalis, masseter, and suprahyoid muscles. The subjects were guided to chew bilaterally and simultaneously each one of the materials, in aleatory sequence. For the study of the masticatory activity the electromyographic signals were processed through rectification, linear envelope and normalization, so that the coefficient of variation obtained from the procedure was comparatively analyzed. All data were submitted to analysis of variance (uni- and multi-varied). RESULTS: The results of this study indicated that the best materials for electromyographic studies on the chewing were Parafilm and cotton ball because they demonstrated the smallest coefficients of variation. CONCLUSION: In addition, Parafilm showed the best palatability. In a general way, these materials are indicated for the accomplishment of electromyographic exams, since they demonstrated a smaller coefficient of variation as compared to the other materials.

Electromyographic analysis of the superior belly of the omohyoid muscle and anterior belly of the digastric muscle in tongue and head movements.

The participation of the superior belly of the omohyoid muscle and anterior belly of the digastric muscle in tongue and head movements was studied eletromyographically in 20 normal young volunteers. A pair of monopolar electrodes was used in each muscle for simultaneous recording of their actions. The muscles act in the following tongue movements: protrusion, right and left lateral movements, placement of the tip of the tongue on soft and hard palates and on the floor of the mouth. The strongest levels of activity of the superior belly of the omohyoid muscle were observed in the placement of the tip of the tongue on the soft palate, coincidentally with a greater dislocation of hyoid bone. Both of the muscles studied did not participate in the head's kinesiology.

Evaluation of electromyographic activity and heart rate responses to isometric exercise. The role played by muscular mass and type.

The purpose of the present study was to examine the relationship between the electromyographic (EMG) activity and heart rate (HR) responses induced by isometric exercise performed by knee extension (KE) and flexion (KF) in men. Fifteen healthy male subjects, 21 +/- 1.3 years (mean +/- SD), were submitted to KE and KF isometric exercise tests at 100% of maximal voluntary contraction (MVC). The exercises were performed with one leg (right or left) and with two legs simultaneously, for 10 s in the sitting position with the hip and knee flexed at 90 degrees. EMG activity (root mean square values) and HR (beats/min) were recorded simultaneously both at rest and throughout the sustained contraction. The HR responses to isometric exercise in KE and KF were similar when performed with one and two legs. However, the HR increase was always significantly higher in KE than KF (P < 0.05), whereas the EMG activity was higher in KE than in KF (P < 0.05), regardless of the muscle mass (one or two legs) involved in the effort. The correlation coefficients between HR response and the EMG activity during KE (r = 0.33, P > 0.05) and KF (r = 0.15, P > 0.05) contractions were not significant. These results suggest that the predominant mechanism responsible for the larger increase in HR response to KE as compared to KF in our study could be dependent on qualitative and quantitative differences in the fiber type composition found in each muscle group. This mechanism seems to demand a higher activation of motor units with a corresponding increase in central command to the cardiovascular centers that modulate HR control.

EMG study of the anterior, superior and posterior auricular muscles in man.

Anterior, superior and posterior auricular muscles were studied electromyographically by means of wire electrodes. During ear movement the three muscles acted as a group and the movement was always directed upwards and backwards. The highest electrical activities were observed during natural smiling and yawning. Mouth opening without the drawing backwards of the comissura labiorum and the displacement of galea aponeurotica also produced electrical activity by the auricular muscles, with however, less intensity and in only 50% of the cases studied.

Occipitofrontalis muscle: functional analysis revealed by electromyography.

The occipital and frontal bellies of the right occipitofrontalis muscle were studied electromyographically in thirty volunteers in various movements, using a special steel electrode (80 microns diameter). The occipital and frontal bellies have independent actions despite the galea aponeurotica. The frontal belly initially raises the homolateral eyebrow, followed by a displacement of the galea aponeurotica, drawing the scalp forward; therefore it is active in the formation of the transversal wrinkling in the forehead. The occipital belly eventually can be active during raising of the eyebrown, nevertheless it does not interfere with the action of the frontal belly. The occipital belly alone is responsible for drawing back the galea aponeurotica. The occipital belly is also active during smiling and yawning, and can be active during the movements of the auricula.

Electromyographic study of the upper, middle and lower portion of the trapezius muscle in the circumduction movement of the arm on a shoulder wheel apparatus.

The upper, middle and lower portions of the trapezius muscle were analysed electromyographically (using a TECA TE-4 electromyograph and a single coaxial needle) in 20 healthy volunteers, during a circumduction movement of the arm, on a shoulder wheel apparatus. All three portions of the muscle were active, but the elevation phase of the arm was more pronounced in movements performed clockwise while the lowering phase was more manifest in movements performed counterclockwise. The position of the wheel gauntlet did not interfere significantly with the results.

Electromyographic analysis of superior belly of the omohyoid muscle and anterior belly of the digastric muscle in mandibular movements.

The superior belly of the omohyoid muscle and the anterior belly of the digastric muscle, were studied electromyographically in 20 young volunteers. For each muscle, 1 pair of monopolar electrodes was employed. One was a surface electrode and the other a needle electrode, which was inserted in the belly of the muscle. The surface electrode was placed 1 cm apart from the needle electrode. The most marked action of both muscles was on the movement of lowering the mandible. They also act in those movements for the performance of which they have associated a component of lowering the jaw, propulsion, laterality to the right and the left and retrusion. They are not active in the resting position and during jaw movements of elevation, extrusion and protrusion. Both muscles are active most of the time, simultaneously, but it is not possible to demonstrate that there is a synchronism between their actions.

Quantitative end qualitative analysis of the electrical activity of rectus abdominis muscle portions.

The purpose of this study was to investigate the electrical behavior pattern of the Rectus abdominis muscle by qualitative and quantitative analysis of the electromyographic signal obtained from its superior, medium and inferior portions during dynamic and static activities. Ten voluntaries (aged X = 17.8 years, SD = 1.6) athletic males were studied without history of muscle skeletal disfunction. For the quantitative analysis the RMS (Root Mean Square) values obtained in the electromyographic signal during the isometric exercises were normalized and expressed in maximum voluntary isometric contraction percentages. For the qualitative analysis of the dynamic activity the electromyographic signal was processed by full-wave rectification, linear envelope and normalization (amplitude and time), so that the resulting curve of the processed signal was submitted to descriptive graphic analysis. The results of the quantitative study show that there is not a statistically significant difference among the portions of the muscle. Qualitative analysis demonstrated two aspects: the presence of a common activation electric pattern in the portions of Rectus abdominis muscle and the absence of significant difference in the inclination angles in the electrical activity curve during the isotonic exercises.

Electromyography study of the portions of the abdominal rectus muscle.

This study objective was to verify the behavior of three portions of the abdominal rectus muscle through a quantitative analysis of the electromyographic signal in different types of abdominal exercises. Ten young male between 16 and 27 years old were studied and they had no previous history of muscle and joint illness. They were well-trained and did seven abdominal exercises chosen considering the types of contraction (isotonic and isometric) as well as the muscle fixation points. The electric activity of the superior, medium (above umbilicus) and inferior (below umbilicus) portions at the left side of the abdominal rectus muscle was taken using Beckman type surface mini-electrodes. The registers were collected from computerized 8-channel Nicholet electromyography equipment, model Viking II. The signals were quantified using the MVA (Maximum Volunteer Activity) software, being considered for analysis the values of RMS (Root Mean Square). The obtained data were submitted to a parametric analysis using the variance analysis (F test) and also the Tukey test, besides a descriptive graphic analysis starting from the average RMS values of each muscle portion. This study results suggest that for the majority of the subjects, the functional activities of the abdominal rectus muscle are performed with electric activity differences among their portions, showing a tendency of producing more electric activity in the superior portion than in the medium and inferior portions. The experiment also demonstrated an absence of a common behavior pattern in the three portions of the ten tested subjects.

Electromyographic study of the longissimus dorsi and iliocostalis lumborum muscles during knee flexion and extension on a plain and on a tilt Roman table.

The objective of this paper was to analyse the activity of the longissimus dorsi and the iliocostalis lumborum muscles--components of the erector spinae muscle--in order to determine: their action potentials during the use of a plain and a tilt Roman table; 2) to compare the action potentials of the two muscles; 3) to verify if the action potential of these two muscles remain constant during the arc of movement--knee flexion and extension--divided into angle ranges, and 4) to compare the action potentials of the muscles in movements performed in a free manner and against resistance. Twenty-three young volunteers were studied electromyographically and each muscle received a needle electrode (Mise) and a surface electrode. The results showed that the table model did not determine any difference in the action potential of the muscles and that, on average, the iliocostalis lumborum muscle developed a slightly higher action potential than the longissimus dorsi muscle during the free flexion of knees on the plain table. In more than 70% of the cases, there was no difference between the action potential of the muscles over the various angle ranges of knee flexion and extension. Relatively higher action potentials were recorded during knee flexion and extension against resistance than during the same movements performed in a free manner. This shows that the paravertebral musculature responds better to an overload (8 kg) imposed on the knee flexor group, confirming the stabilizing role of the longissimus dorsi and iliocostalis lumborum muscles during knee flexion and extension on a Roman table.

The effect of free isotonic and maximal isometric contraction exercises of the hip adduction on vastus medialis oblique muscle: an electromyographic study.

The purpose of this study was to analyse the activity of the vastus medialis oblique (VMO) muscle electromyographically during free isotonic and maximal isometric contraction of the hip adduction with knee extension performing exercises at sitting and in decubitus lateralis positions. Using a 8 channels Nicolet Electromyograph and Beckman surface mini electrodes, the activity of the vastus medialis oblique muscle was recorded among 15 healthy subjects, aged 19 to 33 years, (mean = 24.4, SD = 4.1) without prior knee and hip joints pathology. The sign was recorded in root mean square (RMS), expressed in microvolts. The data were statistically calculated employing an analysis of variance (ANOVA) and the Tukey test, at 5% of significance. The results showed that the electromyographic (EMG) activity of the vastus medialis oblique muscle was significantly greater in both exercises of maximal contraction when compared with free isotonic at decubitus lateralis. On the other hand, there was no significant difference of the electromyographic activity of the vastus medialis oblique muscle between the two exercises of maximal isometric contraction. These findings, within the experimental conditions used, suggest that prior stages of patellofemoral dysfunction, the exercises of hip adduction with knee extension could be performed isometrically or isotonically, at sitting and in decubitus lateralis positions, depending on the biological conditions of each patient.

Electromyographic analysis of the extending muscles of the knee during functional activities.

The purpose of this study is to analyze the behavior of electrical activity of the muscles vastus medialis oblique (VMO), vastus medialis long (VML), and, rectus femoris (RF) during functional activities. The electromyography of the VMO, VML and RF muscles were analyzed in ten healthy volunteers. Signs were collected through superficial electrodes and a electrogoniometer, connected to a signal condition module. The analysis of the results after treating the signals shows us that there is a similar electromyographical behavior in the three studied muscles. Therefore, these discoveries suggest a common electrical behavior pattern especially between VMO and VL muscles in healthy volunteers.

Human identification based on cranial computed tomography scan: a case report.

Today, there is increasing use of CT scanning on a clinical basis, aiding in the diagnosis of diseases or injuries. This exam also provides important information that allows identification of individuals. This paper reports the use of a CT scan on the skull, taken when the victim was alive, for the positive identification of a victim of a traffic accident in which the fingerprint analysis was impossible. The authors emphasize that the CT scan is a tool primarily used in clinical diagnosis and may contribute significantly to forensic purpose, allowing the exploration of virtual corpses before the classic autopsy. The use of CT scans might increase the quantity and quality of information involved in the death of the person examined.