Surface EMG of jaw elevator muscles: effect of electrode location and inter‐electrode distance

Abstract

SUMMARY This study addresses methodological issues on surface electromyographic (EMG) signal recording from jaw elevator muscles. The aims were (i) to investigate the sensitivity to electrode displacements of amplitude and spectral surface EMG variables, (ii) to analyse if this sensitivity is affected by the inter-electrode distance of the bipolar recording, and (iii) to investigate the effect of interelectrode distance on the estimated amplitude and spectral EMG variables. The superficial masseter and anterior temporalis muscles of 13 subjects were investigated by means of a linear electrode array. The percentage difference in EMG variable estimates from signals detected at different locations over the muscle was larger than 100% of the estimated value. Increasing the inter-electrode distance resulted in a significant reduction of the estimation variability because of electrode displacement. A criterion for electrode placement selection is suggested, with which the sensitivity of EMG variables to small electrode displacements was of the order of 2% for spectral and 6% for amplitude variables. Finally, spectral and, in particular, amplitude EMG variables were very sensitive to inter-electrode distance, which thus should be fixed when subjects or muscles are compared in the same or different experimental conditions.

Eletromiografia de superfície em disfunção temporomandibular: revisão sistemática

“…This procedure is carried out with electrodes placed on patients' skin, in general bilaterally. Its relatively technical simplicity allows its use in Dentistry and in clinical research 4 . TMDs investigation and evaluation should include behavioral, emotional and psycho-social factors, in addition to normally observed physical changes 5 .…”

Site-to-site variation of muscle activity and sensitivity in the human anterior temporalis muscle: Implications for contingent stimulation

“…Previous studies reported that surface EMG recordings were influenced by location of the electrodes over the muscle, inter-electrode distance, body posture and psychological factors [25][26][27]. The electrode location has a large influence especially on characteristics of the recorded EMG signal.…”

Effect of occlusal splint thickness on electrical masticatory muscle activity during rest and clenching

“…The subjects were comfortably installed in a chair inside a room with a controlled temperature (22 °C) for 30 minutes. Bipolar surface electrodes (Kendall MedTrace 100 Conductive Adhesive ECG Electrodes, Tyco Healthcare Group LP, Pointe-Claire, Canada) were placed with a distance of 18 mm between them, following the long axis of the muscle fibers of the masseter and anterior temporal muscle on both sides 4,5 ( Figure 1). These electrodes were linked by wires to an amplifier connected to a computer for recording and analysis of muscle activity splint and 4 th and 5 th records were obtained following the same criteria used for the 2 nd and 3 rd records.…”

“…distance between the electrodes and the thickness of the fat layer between the skin and muscles. 4,5 The muscle parameters frequently studied by EMG include postural position or rest, as well as activity during maximum tooth clenching. Such parameters have been used to evaluate the effect of occlusion on normal muscle function, both with and without an interocclusal splint.…”