electromyogram

n. (Abbr. EMG)
A graphic record of the electrical activity of a muscle as recorded by an electromyograph.

EMG

A record of the electrical activity of muscle made by electromyography.

The record obtained by electromyography. Abbreviated EMG.

The human body is an electrochemical organism, although the electrical activities of the body are relatively weak. Nevertheless, a variety of different human electrical activities can be measured through electrodes taped to the skin or scalp. In scientific sleep and dream research, the most important measurements are EEGs (electroencephalograms), which are measurements of brain wave activity, and EOGs (electrooculograms), which measure eye movements to distinguishing between rapid eye movement (REM) and an non-REM sleep. A third measurement usually taken along with an EEG and EOG is an EMG (electromyogram), a measure of muscle tone in the neck that is typically made through electrodes attached to the chin. The EMG helps researchers identify periods of head movement that may interfere with EEG and EOG readings, and is also a secondary indicator of REM periods (because muscular activity is at a standstill during REM sleep).

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