Which electrode site is approximately 10% above the inion?

Which electrode site is approximately 10% above the inion?

• A. T3
• B. Oz
• C. Fpz
• D. T4

Answer: (B)

The key idea is how the 10-20 system places electrodes along the midline using landmarks and percent distances from nasion to inion. The site on the midline at the occipital region, just above the inion by about 10% of that nasion–inion distance, is the occipital midline electrode known as Oz. This location sits behind the back of the head, near the occipital bone, which matches “approximately 10% above the inion.” The other options are not on the midline occipital region: T3 and T4 sit over the temporal lobes to the sides, and Fpz is a frontal midline site.

The key idea is how the 10-20 system places electrodes along the midline using landmarks and percent distances from nasion to inion. The site on the midline at the occipital region, just above the inion by about 10% of that nasion–inion distance, is the occipital midline electrode known as Oz. This location sits behind the back of the head, near the occipital bone, which matches “approximately 10% above the inion.”

The other options are not on the midline occipital region: T3 and T4 sit over the temporal lobes to the sides, and Fpz is a frontal midline site.