Where are the two inferior chin electrodes placed?

Where are the two inferior chin electrodes placed?

• A. Mental foramen
• B. Submentalis
• C. Mastoid
• D. Orbicularis oris

Answer: (B)

Chin EMG relies on placing the two electrodes in the submentalis region, just under the chin where the mentalis muscles are located. Position one electrode on each side of the midline in this area so you capture a clean, bilateral chin muscle signal. This location gives a reliable measure of overall jaw/chin muscle tone, which is essential for distinguishing wakefulness from sleep stages and for detecting REM atonia when tone drops. The mental foramen is a bone landmark, not an electrode site; the mastoid area is used for EEG reference or EOG rather than chin EMG; and the orbicularis oris muscle lies at the lips, not the standard chin EMG placement.

Chin EMG relies on placing the two electrodes in the submentalis region, just under the chin where the mentalis muscles are located. Position one electrode on each side of the midline in this area so you capture a clean, bilateral chin muscle signal. This location gives a reliable measure of overall jaw/chin muscle tone, which is essential for distinguishing wakefulness from sleep stages and for detecting REM atonia when tone drops. The mental foramen is a bone landmark, not an electrode site; the mastoid area is used for EEG reference or EOG rather than chin EMG; and the orbicularis oris muscle lies at the lips, not the standard chin EMG placement.