Evidence that the human jaw stretch reflex increases the resistance of the mandible to small displacements.

Cooker, Harry S.; Larson, Charles R.; Luschei, Erich S.

doi:10.1113/jphysiol.1980.sp013462

Cited by 97 publications

(26 citation statements)

References 25 publications

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“…In interpreting their experiments on human jaw muscles, Cooker, Larsen & Luschei (1980) used a different method of estimating the non-reflex resistance, which depended partly on the known properties of the jaw muscles, and partly on the response of cat gastrocnemius muscles to sinusoidal stretching.…”

Section: Discussionmentioning

confidence: 99%

Forces generated at the thumb interphalangeal joint during imposed sinusoidal movements

Brown

Rack

Ross

1982

The Journal of Physiology

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SUMMARY1. A method is described for driving the interphalangeal joint of the thumb through repeated sinusoidal flexion-extension movements, while immobilizing other joints of the wrist and hand.2. The joint met the sinusoidal movement with a force that fluctuated in an approximately sinusoidal manner. This paper is concerned with the relationship between the position and force sinusoids.3. When the thumb was relaxed the forces were small, but when the flexor pollicis longus was tetanically stimulated there was a large force change in response to each cycle of the movement. In either case, the maximum resistance to extension occurred during the later part of the extension movement, some 20O45O in advance of maximum extension. A similar result was obtained when the subject exerted a maximal voluntary flexing force.4. The resistance to movement can conveniently be displayed as a stiffness vector, the amplitude of which is the force/displacement, and the phase is the angle by which the force sinusoid leads the position sinusoid.5. When the subject maintained a continuous, though sub-maximal, flexing effort the timing of the force fluctuations changed with changing frequency of movement in a characteristic way, and the stiffness vectors described a C-shaped or spiral path. With increasing frequency the stiffness vectors moved round this path in a clockwise direction.6. For descriptive purposes the resistance to movement can usefully be regarded as the vector sum of a reflex and a non-reflex component. Since the reflex pathway involves significant conduction delays, the reflex force can be expected to appear later in the cycle of a higher frequency movement, and give rise to a vector which moves round in a clockwise direction as the frequency increases. The non-reflex stiffness, however, changes much less with frequency.7. It is concluded that the size of the C-shaped or spiral vector path gives an indication of the strength of the reflex activity, while the position of the high frequency points gives an indication of the noni-reflex resistance to the movement.

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Section: Discussionmentioning

confidence: 99%

Forces generated at the thumb interphalangeal joint during imposed sinusoidal movements

Brown

Rack

Ross

1982

The Journal of Physiology

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“…Relationship of force changes to reflex responses Lamarre &Lund (1975) andCooker et al (1980), who were unable to demonstrate a long-latency response in the masseter, concluded that the reflex increase in force evoked by loading the human masseter during an isotonic bite or by stretching the muscle was the result of the monosynaptic response. In the present study, we found that, although jaw-jerk stimuli evoke a high-amplitude monosynaptic reflex in the EMG, little or no force is generated by this electrical response in most subjects.…”

Section: Reflex Pathwaysmentioning

confidence: 99%

“…Godaux & Desmedt, 1975;Murray & Klineberg, 1984). The few studies in which controlled stretch of the jaw-closing muscles has been used to evoke stretch reflexes include those of Marsden, Merton & Morton (1972), Lamarre & Lund (1975) and Cooker, Larson & Luschei (1980) in humans, and Goodwin, Hoffman & Luschei (1978) in monkeys. The characteristic response of most limb muscles to stretch is an initial burst of excitation at monosynaptic latency, followed by a more sustained excitation at longer latency.…”

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confidence: 99%

“…This claim is based mainly on the earlier observation that the only reflex response to stretch of the human jaw-closing muscles seen in most studies is the segmental jaw-jerk reflex (e.g. Lamarre & Lund, 1975;Goodwin et al 1978;Cooker et al 1980). Marsden et al (1976 reported that the latency of the first excitatory response to stretch occurs at 12-14 ms in masseter.…”

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confidence: 99%

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Stretch reflexes in human masseter.

Poliakov

Miles

1994

The Journal of Physiology

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The reflex response to stretch in most contracting human muscles includes both a short‐latency, probably monosynaptic, excitatory component, and a longer‐latency, polysynaptic excitation. However, it has been claimed that stretch of the jaw‐closing muscles evokes only the short‐latency response in masseter. This question was re‐examined, using controlled stretches of varied rates and durations. Very brief, rapid stretches analogous to the stimuli used to investigate the ‘jaw‐jerk’ reflex in earlier studies evoked a prominent excitatory peak in the electromyogram at monosynaptic latency excitation, but little or no longer‐latency excitation. This response could be produced even by stimuli that were barely detectable by the subject. However, this prominent electrical response did not produce a measurable increase in biting force. In contrast, slower stretches evoked both a short‐ and a longer‐latency excitatory response in the surface electromyogram, as in most limb muscles. It is shown that the absence of a long‐latency excitatory response in earlier studies can be explained by the powerful reflex disfacilitation of the motoneurones that occurred at the end of the brief stretches used. Depending on the duration of the stretch, this disfacilitation is often sufficient to mask or abolish the long‐latency reflex. The reflex response to stretches was not markedly affected by blocking the activation of mechanoreceptors around the teeth with local anaesthetic, indicating that receptors around the teeth cannot be playing more than a minor role in the response. The stretch‐induced increase in force became greater as the velocity of the stretch decreased.

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“…Mathematical models provide the most information about a system, and they are the most difficult to obtain. Linear system-identification methods had been used extensively to characterize the dynamics of ankle [14], wrist [15], elbow [16] and jaw [17].…”

Section: Literature Reviewmentioning

confidence: 99%

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Evidence that the human jaw stretch reflex increases the resistance of the mandible to small displacements.

Cited by 97 publications

References 25 publications

Forces generated at the thumb interphalangeal joint during imposed sinusoidal movements

Forces generated at the thumb interphalangeal joint during imposed sinusoidal movements

Stretch reflexes in human masseter.

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