Which two points on the 10-20 placement system are used to locate F3?

Which two points on the 10-20 placement system are used to locate F3?

• A. C3 and FP1
• B. FP1 and Fz
• C. Fz and F8
• D. Fz and FP1

Answer: (A)

In the 10-20 system, electrode positions are defined by fixed skull landmarks, and each site is pinpointed by using two nearby reference points to triangulate its spot on the scalp. For locating F3, the left frontal site, the two anchor points used are FP1 (frontopolar left) and C3 (left central). FP1 anchors the anterior-left boundary, while C3 provides the lateral/central reference, together guiding you to the correct left-frontal position that is named F3. The other pairs either involve midline references or locations on the opposite side, which would not place the electrode at F3.

In the 10-20 system, electrode positions are defined by fixed skull landmarks, and each site is pinpointed by using two nearby reference points to triangulate its spot on the scalp. For locating F3, the left frontal site, the two anchor points used are FP1 (frontopolar left) and C3 (left central). FP1 anchors the anterior-left boundary, while C3 provides the lateral/central reference, together guiding you to the correct left-frontal position that is named F3. The other pairs either involve midline references or locations on the opposite side, which would not place the electrode at F3.