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Fine-wire Electrode (fine-wire + electrode)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Genioglossus muscle activity during rhythmic open,close jaw movements

JOURNAL OF ORAL REHABILITATION, Issue 8 2000
S. Hiyama
The purpose of this study was to examine genioglossus muscle activity during rhythmic open,close jaw movements. The electromyographic activity of the genioglossus muscle was recorded with a bipolar fine-wire electrode in six healthy males. The electromyographic activities of the ipsilateral masseter and digastric muscles were simultaneously recorded with bipolar surface electrodes. The subjects were instructed to perform rhythmic open,close jaw movements in time with a metronome set at 23, 27, 33, 42 and 50 beats/min. In all of the subjects, rhythmic electromyographic activity of the genioglossus muscle was recorded in both the jaw-opening and jaw-closing phases. The activity of the genioglossus muscle was predominantly recorded in the jaw-opening phase in two subjects, and in the jaw-closing phase in two subjects. The burst duration of the electromyographic activity of the genioglossus muscle changed linearly in accordance with the cycle duration. However, the latency from the onset of the electromyographic activity of the masseter or digastric muscle to that of the genioglossus muscle was almost constant, independent of the cycle duration. Based on these findings, we conclude that the activity of the human genioglossus muscle is closely linked to that of masticatory muscles under the control of a closely related central pattern generator. [source]

Motor unit recruitment and derecruitment induced by brief increase in contraction amplitude of the human trapezius muscle

THE JOURNAL OF PHYSIOLOGY, Issue 2 2003
C. Westad
The activity pattern of low-threshold human trapezius motor units was examined in response to brief, voluntary increases in contraction amplitude (,EMG pulse') superimposed on a constant contraction at 4,7% of the surface electromyographic (EMG) response at maximal voluntary contraction (4,7% EMGmax). EMG pulses at 15,20% EMGmax were superimposed every minute on contractions of 5, 10, or 30 min duration. A quadrifilar fine-wire electrode recorded single motor unit activity and a surface electrode recorded simultaneously the surface EMG signal. Low-threshold motor units recruited at the start of the contraction were observed to stop firing while motor units of higher recruitment threshold stayed active. Derecruitment of a motor unit coincided with the end of an EMG pulse. The lowest-threshold motor units showed only brief silent periods. Some motor units with recruitment threshold up to 5% EMGmax higher than the constant contraction level were recruited during an EMG pulse and kept firing throughout the contraction. Following an EMG pulse, there was a marked reduction in motor unit firing rates upon return of the surface EMG signal to the constant contraction level, outlasting the EMG pulse by 4 s on average. The reduction in firing rates may serve as a trigger to induce derecruitment. We speculate that the silent periods following derecruitment may be due to deactivation of non-inactivating inward current (,plateau potentials'). The firing behaviour of trapezius motor units in these experiments may thus illustrate a mechanism and a control strategy to reduce fatigue of motor units with sustained activity patterns. [source]

Electromyographic activity of the palatinus and palatopharyngeus muscles in exercising horses

EQUINE VETERINARY JOURNAL, Issue 5 2007
S. J. HOLCOMBE
Summary Reasons for performing study: Determining the respiratory related activity of the palatinus and palatopharyngeus muscles in exercising horses is relevant because dysfunction of these muscles has been implicated in the pathogenesis of dorsal displacement of the soft palate. Objective: To determine if the palatinus and palatopharyngeus muscles have respiratory activity that increases with intensity in exercising horses. Methods: Electromyographic activity was measured in the palatinus and palatopharyngeus muscles using bipolar fine-wire electrodes while the horses completed an incremental exercise treadmill protocol. Results: Both muscles displayed synchronous expiratory activity that increased significantly (P<0.05) with exercise intensity. Phasic expiratory activity of the palatinus increased 390 ± 98%, whereas phasic expiratory activity of the palatopharyngeus increased by 198 ± 30% as the treadmill speed increased from 6 to 12 m/s. Conclusions: The palatinus and palatopharyngeus muscles may be important respiratory muscles, functioning to stabilise the position of the soft palate during intense exercise. Clinical relevance: The predominant expiratory activity of these muscles may be associated with specific muscle function related to exercise or distinct upper airway phenomena of an obligate nasal breather, such as the horse. [source]

Antero-posterior activity changes in the superficial masseter muscle after exposure to experimental pain

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2002
Jens C. Türp
The aim of this randomized, controlled, double-blind study was to examine how the activation pattern of the masseter muscle changes during natural function when experimental pain is induced in a discrete anterior area of the muscle. In 20 subjects, three bipolar surface electrodes and three intramuscular fine-wire electrodes (antero-posterior mapping) were simultaneously attached above and in the right masseter muscle to record the electromyographic (EMG) activity during unilateral chewing before and after infusion of a 0.9% isotonic and 5% hypertonic saline bolus in the anterior area of the muscle. The activity of the contralateral masseter muscle was registered by surface electrodes. In addition, the development of pain intensity was quantitatively measured with a numerical rating scale (NRS). While both saline concentrations caused pain, the hypertonic solution evoked stronger pain. The experiments also provided evidence of a significant although differential activity reduction of the ipsilateral masseter muscle in the antero-posterior direction. The activity reduction decreased with increasing distance from the location of the infusion. The results support the idea that the strategy of differential activation protects the injured muscle while simultaneously maintaining optimal function. [source]