Effect of voluntary contraction of the masseter and other muscles upon the masseteric reflex in man

Hannam, A.G.

doi:10.1136/jnnp.35.1.66

Cited by 22 publications

(12 citation statements)

References 13 publications

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“…The results of one such series of trials are shown in Fig. 2 (Hannam, 1972). No differences were found when comparing the latency of the responses evoked 24 LOAD COMPENSATION IN HUMAN MASSETER MUSCLES 25 by the motor with those evoked by the hammer.…”

Section: Jaw-jerk Reflexmentioning

confidence: 94%

Load compensation in human masseter muscles.

Lamarre¹,

Lund²

1975

The Journal of Physiology

106

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SUMMARY1. The reaction of masseter and digastric muscles to changes in the load applied during a movement was studied in human volunteers.2. Rapid stretch of the jaw-closing muscles evoked a monosynaptic jaw-jerk reflex response in the masseteric electromyogram (e.m.g.) after a delay of 6-8 msec.3. The averaged integrated e.m.g. activity of the masseter was increased 5-10 msec after the rapid application of a load during voluntary closure of the jaw. It was not necessary to stretch the muscle to obtain this apparently monosynaptic response.4. A compensatory increase in the velocity of movement followed 6-10 msec after the e.m.g. peak.5. Unloading the masseter muscle during contraction was followed by a fall in e.m.g. activity, beginning after a latency of 6 5-11 msec, with later phases of depression beginning 27-36 and 60-70 msec after unloading.6. The spindle-poor digastric muscles were not monosynaptically activated during loading, but responded with a latency of 24-34 msec. 7. It is concluded that monosynaptic e.m.g. changes are a prominent feature of the load compensation system in human jaw-closing muscles but not in jaw-opening muscles.

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Section: Jaw-jerk Reflexmentioning

confidence: 94%

Load compensation in human masseter muscles.

Lamarre¹,

Lund²

1975

The Journal of Physiology

106

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“…Although this may be significant, it cannot account for all the data scatter observed, in view of the apparently independent variation of masseter and temporal muscle data. A similar deduction may be made from the variability observed by Hannam,8 where the force level was presumably more accurately controlled and where the voluntary force level was always rising, although possibly at different rates, at the moment of stimulation.…”

Section: Stimulus Mis2mentioning

confidence: 61%

“…The amplitude of the first downward deflection of the accelerometer signal was measured. Calibrations: Horizontal:8 ms, Vertical: 50 m/S2 (accelerometer) 015 mV (EMG) zero by clenching on the transducer. Positive and negative full scale deflections of the meter corresponded to +250 g. The dimensions of the transducer determined the jaw position, which was approximately 8 mm open from the position of maximum closure.…”

mentioning

confidence: 99%

The effect of stimulus strength on the jaw-jerk response in man.

Lewis¹,

Pilcher²,

Yemm³

1980

Journal of Neurology, Neurosurgery & Psychiatry

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S U M MARY The jaw-jerk response was elicited in seven adult male subjects by tapping on the chin in a downward direction. Tho jaw-jerk response, elicited in jaw-closing muscles by a downward tap on the chin, is sometimes used as a clinical test of the integrity of the trigeminal neuromuscular pathways. The test is applied in a qualitative;fashion, where simply the presence or absence of a muscle response is recorded, using electromyographic techniques.Some attempts to quantify the response of the masseter muscle have been made. Many of these have been concerned with the latency.' Difficulties of measurement arise, both in assessment of the moment of application of the stimulus, and of detection of the first evidence of a response. The response itself is followed by a silent period when the muscle is active at the time of stimulation, as in other muscles.2 The onset and duration of this silent period have also been investigated for the masseter muscle.' Furthermore the silent period duration in jaw-closing muscles has been examined in patients with muscular disorders of the region (tcmporomandibular dysfunction).'' The results are conflicting, and in any case neither the origin of the silent period, nor the relationship of its

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“…It has also been termed “jaw jerk”, “masseter reflex”, “temporomasseter reflex”, and “mandibular reflex” (2). The human jaw‐closing muscles are richly endowed with muscle spindles and the spindle afferents make excitatory connections to the motoneurons of jaw‐closing muscles (3). During isometric contraction, the function of the alpha‐motor and fusimotor system can be revealed during different conditions by examination of the jaw‐stretch reflexes in the EMG of the muscle (4).…”

mentioning

confidence: 99%

“…The level of background EMG activity as well as the biting task (1,14) have also been considered to influence the reflex amplitude, however, all these parameters have not been examined in detail with a highly controlled stretch device. The purpose of this study was, therefore, (1) to systematically investigate the influence of methodological parameters (clenching level, ramp time, displacement, biting position, local anesthetics around teeth) on the jaw‐stretch reflex, (2) to study the reproducibility of the jaw‐stretch reflex both within and between sessions, and (3) to provide insight into the mechanisms underlying the excitability of the motoneuron pool.…”

mentioning

confidence: 99%

Influence of methodological parameters on human jaw‐stretch reflexes

Wang

Svensson

2001

European J Oral Sciences

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The influence of methodological parameters and experimental conditions on the human jaw-stretch reflex was studied in healthy subjects in order to develop a reliable tool for investigation of the excitability of motoneuron pool. Short-latency excitatory reflex responses were evoked by a custom-made stretch device with the subjects biting on a jaw-bar with their front teeth. The displacement and ramp time of the stretches were accurately controlled and automatically triggered by a computer. The reflex responses were measured in the surface electromyogram (EMG) of the masseter and anterior temporalis muscles with online monitoring of the clenching level. The peak-to-peak amplitude of the jaw-stretch reflex was shown to be proportional to the level of EMG activity during isometric contractions, to increase proportionally with increasing stretch displacement at a given ramp time, and to decrease proportionally with increasing ramp time at a given stretch displacement. There were no significant differences in the reflex amplitude between repeated recordings within one session or between different sessions. Local anesthetic around the lower incisors as well as the upper incisors had no significant influence on the reflex amplitude. However, different biting positions on the bars of the stretch device significantly influenced the amplitude of the stretch reflex.

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Effect of voluntary contraction of the masseter and other muscles upon the masseteric reflex in man

Cited by 22 publications

References 13 publications

Load compensation in human masseter muscles.

Load compensation in human masseter muscles.

The effect of stimulus strength on the jaw-jerk response in man.

Influence of methodological parameters on human jaw‐stretch reflexes

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