Esoteric Techniques

Jay A. Liveson and Dong M. Ma

in Laboratory Reference for Clinical Neurophysiology

Published in print May 1999 | ISBN: 9780195129243
Published online March 2012 | e-ISBN: 9780199847792 | DOI:
Esoteric Techniques

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The jaw jerk (or masseter reflex) is a monosynaptic reflex that presents an opportunity to study the peripheral and central function of the trigeminal nerve. It is elicited by tapping the midpoint of the chin with a special reflex hammer containing a microswitch to simultaneously trigger the sweep of the oscilloscope. Surface recordings are made bilaterally from the masseter muscles. Stimulation of the spinal cord can be accomplished with specialized stimulators, capable of delivering high voltages or high-density magnetic fields. The cervical spinal cord can be stimulated, however, with equipment normally present in the electromyography laboratory. The latency obtained is a combination of conduction time through the spinal cord, plus peripheral conduction through the sciatic nerve. The peripheral component can be determined by eliciting the corresponding M and minimal F waves on peroneal stimulation at the fibular head.

Keywords: jaw jerk; trigeminal nerve; spinal cord; peripheral conduction; fibular head; microswitch; masseter muscles; sciatic nerve; electromyography

Chapter.  2218 words. 

Subjects: Neuroscience

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