The two inferior chin electrodes are placed on the:

The two inferior chin electrodes are placed on the:

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

Answer: (B)

The two inferior chin electrodes are placed in the submentalis region, under the chin, over the submental (mentalis) muscles. This position captures the tone of the chin muscles, which is exactly what chin EMG aims to measure for distinguishing REM (low tone) from other sleep stages. Placing them here provides a robust, consistent signal with less contamination from lip movements. Placing electrodes on the mental foramen isn’t aMuscle site used for EMG; it’s a bony/landmark area, so it wouldn’t give the intended muscle activity. The mastoid region is commonly used as a reference point for EEG/EMG, not as the site for the chin EMG recording itself. The orbicularis oris, while a facial muscle around the lips, would reflect lip movements rather than the deeper chin muscle tone used for sleep stage scoring.

The two inferior chin electrodes are placed in the submentalis region, under the chin, over the submental (mentalis) muscles. This position captures the tone of the chin muscles, which is exactly what chin EMG aims to measure for distinguishing REM (low tone) from other sleep stages. Placing them here provides a robust, consistent signal with less contamination from lip movements.

Placing electrodes on the mental foramen isn’t aMuscle site used for EMG; it’s a bony/landmark area, so it wouldn’t give the intended muscle activity. The mastoid region is commonly used as a reference point for EEG/EMG, not as the site for the chin EMG recording itself. The orbicularis oris, while a facial muscle around the lips, would reflect lip movements rather than the deeper chin muscle tone used for sleep stage scoring.