Electromyography of superficial cervical muscles with exertion in the sagittal, coronal and oblique planes.
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The purpose of the current study was twofold: (1) to determine the isometric force and electromyographic (EMG) relationship of the sternocleidomastoid, splenii and trapezii muscles bilaterally in graded and maximal exertions in the sagittal, coronal and oblique planes. and (2) to develop regression equations to predict force based on the EMG scores. A newly designed and validated cervical isometric strength testing device was used to measure the cervical muscle isometric strength and force/EMG relationship in cervical flexion, extension, bilateral lateral flexion, bilateral anterolateral flexion, and bilateral posterolateral extension, all beginning with an upright seated neutral posture. A group of 40 healthy subjects were asked to exert their cervical motions in the directions of interest, while the force output and EMG from the sternocleidomastoids, splenii, and trapezii were sampled bilaterally at 1 kHz. ANOVA, correlation, and regression analyses were carried out. The force and EMG scores were significantly different between the directions of effort (P<0.01). All regressions were significant (P<0.01). All subjects registered the highest forces in pure extension and the lowest in pure flexion, showing a gradual decrease from the posterior to anterior direction. There was a modest correlation between EMG of the investigated muscles and force (r=0.15-0.76, P<0.01). EMG output was, for example, approximately 66% higher in flexion than in extension (while force output was roughly 30% less in flexion than extension) - thus relatively more muscle activity was required in flexion than extension to generate a given force. The intermediate positions (i.e. anterolateral flexion) revealed force/EMG ratio scores that were intermediate in relation to the force/EMG ratios for pure flexion and pure extension. The cervical muscle strength and cervical muscle EMG are therefore dependent on the direction of effort. (+info)
Glossopharyngeal and neck accessory muscle breathing in a young adult with C2 complete tetraplegia resulting in ventilator dependency.
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BACKGROUND AND PURPOSE: This case report describes the use of glossopharyngeal breathing (GPB) and neck accessory muscle breathing (NAMB) in the treatment of an individual who was dependent on a ventilator secondary to a spinal cord injury. CASE DESCRIPTION: The patient was a 19-year-old man with C2 complete tetraplegia. He received a 5-week inpatient program of GPB training 3 to 4 times per week. A 4-week NAMB training program followed. OUTCOME: Following GPB training, forced vital capacity increased 35-fold, time off the ventilator improved from 0 to 30 minutes, and a nonfunctional cough became a weak functional cough. After NAMB training, the patient was able to be off the ventilator for 2 minutes. DISCUSSION: Increased ventilatory capability has the potential to affect patients' quality of life by improving cough function and decreasing dependence on a ventilator in the event of accidental disconnection. (+info)
Neck muscle vibration induces lasting recovery in spatial neglect.
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OBJECTIVES: To evaluate whether neck muscle vibration is an effective technique for neglect rehabilitation, with lasting beneficial effects. METHODS: The effects of differential treatment of visual exploration training alone or in combination with neck muscle vibration were evaluated in a crossover study of two matched groups of 10 patients suffering from left sided neglect. Each group received a sequence of 15 consecutive sessions of exploration training and combined treatment. The effects of treatment were assessed with respect to different aspects of the neglect disorder such as impaired perception of the egocentric midline, exploration deficits in visual and tactile modes, and visual size distortion. The transfer of treatment effects to activities of daily living was examined by a reading test and a questionnaire of neglect related everyday problems. All variables were measured six times: three baseline measurements, two post-treatment measurements, and one follow up after two months. RESULTS: The results showed superior effects of combination treatment. A specific and lasting reduction in the symptoms of neglect was achieved in the visual mode, which transferred to the tactile mode with a concomitant improvement in activities of daily living. The improvement was evident two months after the completion of treatment. In contrast, isolated exploration training resulted in only minor therapeutic benefits in visual exploration without any significant transfer effects to other tasks. CONCLUSIONS: Neck muscle vibration is a decisive factor in the rehabilitation of spatial neglect and induces lasting recovery when given as a supplement to conventional exploration training. (+info)
Neck muscle responses to stimulation of monkey superior colliculus. I. Topography and manipulation of stimulation parameters.
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The role of the primate superior colliculus (SC) in orienting head movements was studied by recording electromyographic (EMG) activity from multiple neck muscles following electrical stimulation of the SC. Combining SC stimulation with neck EMG recordings provides an objective and sensitive measure of the SC drive onto neck muscle motoneurons, particularly in relation to evoked gaze shifts. In this paper, we address how neck EMG responses to SC stimulation in head-restrained monkeys depend on the rostrocaudal, mediolateral, and dorsoventral location of the stimulating electrode within the SC and vary with manipulations of the eye position prior to stimulation onset and changes in stimulation current and duration. Stimulation predominantly evoked EMG responses on the muscles obliquus capitis inferior, rectus capitis posterior major, and splenius capitis. These responses became larger in magnitude and shorter in onset latency for progressively more caudal stimulation locations, consistent with turning the head. However, evoked responses persisted even for more rostral stimulation locations usually not associated with head movements. Manipulating initial eye position revealed that the magnitude of evoked responses became stronger as the eyes attained positions contralateral to the side of stimulation, consistent with a summation between a generic command evoked by SC stimulation and the influence of eye position on tonic neck EMG. Manipulating stimulation current and duration revealed that the relationship between gaze shifts and evoked EMG responses is not obligatory: short-duration (<20 ms) or low-current stimulation evoked neck EMG responses in the absence of gaze shifts. However, long-duration stimulation (>150 ms) occasionally revealed a transient neck EMG response aligned on the onset of sequential gaze shifts. We conclude that the SC drive to neck muscle motoneurons is far more widespread than traditionally supposed and is relayed through intervening elements which may or may not be activated in association with gaze shifts. (+info)
Neck muscle responses to stimulation of monkey superior colliculus. II. Gaze shift initiation and volitional head movements.
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We report neck muscle activity and head movements evoked by electrical stimulation of the superior colliculus (SC) in head-unrestrained monkeys. Recording neck electromyography (EMG) circumvents complications arising from the head's inertia and the kinetics of muscle force generation and allows precise assessment of the neuromuscular drive to the head plant. This study served two main purposes. First, we sought to test the predictions made in the companion paper of a parallel drive from the SC onto neck muscles. Low-current, long-duration stimulation evoked both neck EMG responses and head movements either without or prior to gaze shifts, testifying to a SC drive to neck muscles that is independent of gaze-shift initiation. However, gaze-shift initiation was linked to a transient additional EMG response and head acceleration, confirming the presence of a SC drive to neck muscles that is dependent on gaze-shift initiation. We forward a conceptual neural architecture and suggest that this parallel drive provides the oculomotor system with the flexibility to orient the eyes and head independently or together, depending on the behavioral context. Second, we compared the EMG responses evoked by SC stimulation to those that accompanied volitional head movements. We found characteristic features in the underlying pattern of evoked neck EMG that were not observed during volitional head movements in spite of the seemingly natural kinematics of evoked head movements. These features included reciprocal patterning of EMG activity on the agonist and antagonist muscles during stimulation, a poststimulation increase in the activity of antagonist muscles, and synchronously evoked responses on agonist and antagonist muscles regardless of initial horizontal head position. These results demonstrate that the electrically evoked SC drive to the head cannot be considered as a neural replicate of the SC drive during volitional head movements and place important new constraints on the interpretation of electrically evoked head movements. (+info)
Neck muscle vibration and spatial orientation during stepping in place in humans.
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Unilateral long-lasting vibration was applied to the sternomastoid muscle to assess the influence of asymmetric neck proprioceptive input on body orientation during stepping-in-place. Blindfolded subjects performed 3 sequences of 3 trials, each lasting 60 s: control, vibration applied during stepping (VDS), and vibration applied before stepping (VBS). VDS caused clear-cut whole body rotation toward the side opposite to vibration. The body rotated around a vertical axis placed at about arm's length from the body. The rotation did not begin immediately on switching on the vibrator. The delay varied from subject to subject from a few seconds to about 10 s. Once initiated, the angular velocity of rotation was remarkably constant (about 1 degrees /s). In VBS, at the beginning of stepping, subjects rotated for a while as if their neck were still vibrated. At a variable delay, the direction of rotation reversed, and the effects were opposite to those observed during VDS. Under no condition did head rotation, head roll, or lateral body tilt accompany rotation. The results confirm and extend the notion that the neck proprioceptive input plays a major role in body orientation during locomotion. The body rotation does not seem to depend on the same mechanisms that modify the erect posture; rather, the asymmetric neck input would seem to modify the egocentric body-centered coordinate system. (+info)
Breathing modes, body positions, and suprahyoid muscle activity.
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AIM: To determine (1) how electromyographic activities of the genioglossus and geniohyoid muscles can be differentiated, and (2) whether changes in breathing modes and body positions have effects on the genioglossus and geniohyoid muscle activities. METHOD: Ten normal subjects participated in the study. Electromyographic activities of both the genioglossus and geniohyoid muscles were recorded during nasal and oral breathing, while the subject was in the upright and supine positions. The electromyographic activities of the genioglossus and geniohyoid muscles were compared during jaw opening, swallowing, mandibular advancement, and tongue protrusion. RESULTS: The geniohyoid muscle showed greater electromyographic activity than the genioglossus muscle during maximal jaw opening. In addition, the geniohyoid muscle showed a shorter (P < 0.05) latency compared with the genioglossus muscle. Moreover, the genioglossus muscle activity showed a significant difference among different breathing modes and body positions, while there were no significant differences in the geniohyoid muscle activity. CONCLUSION: Electromyographic activities from the genioglossus and geniohyoid muscles are successfully differentiated. In addition, it appears that changes in the breathing mode and body position significantly affect the genioglossus muscle activity, but do not affect the geniohyoid muscle activity. (+info)
Experimental device for detecting laryngeal movement during swallowing.
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It has been reported that swallowing is a rhythmic movement, in which the onset of the oro-pharyngeal stage of swallowing starts from the mylohyoid muscle, followed by movement of the oral and pharyngeal muscles, and reaching the superior esophageal sphincter muscle. This is defined as the oro-pharyngeal stage of swallowing. It has also been reported that along with this movement, the larynx elevates in an antero-superior direction. To investigate the swallowing movement, it would be useful to be able to detect the start of swallowing movements from the body surface. Such a device was designed in this study to investigate the relationships between the onset of laryngeal movement and the EMG initiation of the anterior digastric muscle. Although experimental conditions must be further examined, we were able to record the reproducible movement and the position of larynx using our device provides another tool for studying the swallowing movement. (+info)