When the measured distance from Cz to T4 is 14 cm, what is the distance from C4 to T4?

To determine the distance from C4 to T4 when the distance from Cz to T4 is measured to be 14 cm, it’s essential to understand the standard measurements used in EEG electrode placement according to the International 10-20 system.

In this system, the distances between various electrode landmarks are proportional. The electrode Cz represents the central midline, and the placement of C4 is located 10% of the total distance from Cz to the temporal region where T4 is situated. The distance from Cz to T4 is 14 cm, meaning that the total length can be standardized as a whole where the smaller subdivisions can be derived.

If the distance from Cz to T4 is partitioned, C4 would be positioned halfway between Cz and T4 as it is 5 cm left from T4. Therefore, to find the distance from C4 to T4, we can simply calculate half of the distance from Cz to T4. Since the distance from Cz to T4 is 14 cm, we take 7 cm to reach T4 from C4.

Thus, measuring from C4 to T4 accounts for 7 cm, confirming that the distance is indeed 7.0 cm. This interpretation aligns with the standardized landmark