The document describes the procedures for placing electrodes according to the 10-20 system. It involves taking measurements from defined landmarks on the head and dividing them into percentages to locate standard electrode positions. The first measurement is taken from the nasion to the inion in the anterior-posterior plane and divided into 5 sections labeled Fp, Fz, Cz, Pz, and Oz. A second measurement is taken between the preauricular points through Cz and divided similarly. Additional electrodes T1-T6, F7-F10, and O1-O2 are also described.

1. Electrode placement-
10-20 systems
BY -RAKESH KUMAR

2. MAJOR LAND MARK
Nasion-base of nose where nasal and frontal bone unite.

3. Inion - prominent point on occipital protuberance
MAJOR LAND MARK

4. MAJOR LAND MARK
CC
Auricular points Is just anterior to the tragus at root of helix

5. Central point Cz localization
First a measurement is taken from Nasion to Inion

6. CC
Second measurement from one tragus to other side tragus
Central point Cz localization

7. Cz-intersection point of the AP and coronal measurement
cz
Central point Cz localization

8. Anterior to posterior measument
z
z
z
z
The first measurement is in the anterior-posterior plane through the vertex,
taken from the Nasion to the Inion.

9. Anterior to posterior measument
z
z
z
z
1
This AP Measurement divided into 5 segments- Fp,Fz,Cz,Pz,Oz

10. Anterior to posterior measument
z
z
z
z
2
This AP Measurement divided into 5 segments- Fp,Fz,Cz,Pz,Oz

11. Anterior to posterior measument
z
z
z
z
3
This AP Measurement divided into 5 segments- Fp,Fz,Cz,Pz,Oz

12. Anterior to posterior measument
z
z
z
z
4
This AP Measurement divided into 5 segments- Fp,Fz,Cz,Pz,Oz

13. Anterior to posterior measument
z
z
z
z
1
5
This AP Measurement divided into 5 segments- Fp,Fz,Cz,Pz,Oz

14. Anterior to posterior
measument
z
z
z
z
The first mark is placed at 10% posterior to Nasion of the
total measurement and labelled Fp.

15. z
z
z
z
z
The second, third, fourth and fifth marks are placed at 20%
intervals of the total measurement and label Fz, Cz, Pz, and Oz .
Anterior to posterior measument

16. z
z
z
z
z
The second, third, fourth and fifth marks are placed at 20%
intervals of the total measurement and label Fz, Cz, Pz, and Oz .
Anterior to posterior measument

17. z
z
z
z
z
The second, third, fourth and fifth marks are placed at 20%
intervals of the total measurement and label Fz, Cz, Pz, and Oz .
Anterior to posterior measument

18. z
z
z
z
z
z
z
The second, third, fourth and fifth marks are placed at 20%
intervals of the total measurement and label Fz, Cz, Pz, and Oz .
Anterior to posterior measument

19. Lateral measurement of the central coronal plane starts at the left preauricular
point, Just anterior To tragus through the Cz to the right preauricular point.
Coronal measurement

20. Coronal measurement
Lateral measurement of the central coronal plane starts at the left preauricular
point, Just anterior To tragus through the Cz to the right preauricular point.

21. Coronal measurement
Lateral measurement of the central coronal plane starts at the left preauricular
point, Just anterior To tragus through the Cz to the right preauricular point.

22. Coronal measurement
Lateral measurement of the central coronal plane starts at the left preauricular
point, Just anterior To tragus through the Cz to the right preauricular point.

23. A mark is placed at 10% of this measurement from the
preauricular points and labelled T3 on left and T4 on right
Coronal measurement

24. Coronal measurement
A mark is placed at 10% of this measurement from the
preauricular points and labelled T3 on left and T4 on right

25. A mark is placed in that line of 20 % of total length on both
side are marked C3 and C4 from T3 and T4 respectively..
Coronal measurement

26. A mark is placed in that line of 20 % of total length on both
side are marked C3 and C4 from T3 and T4 respectively..
Coronal measurement

27. Circumferential measurement
A circumferential measurement is then taken over the temporal
lobes from the midline Fp position to the midline O position
through T3 and T4 in left and right side respectively.

28. Circumferential measurement

29. Circumferential measurement
T4

30. Circumferential measurement
A mark is 10 % from Fp to either side as Fp1 and Fp2.

31. Fp2
A mark is 10 % from Fp to either side as Fp1 and Fp2.
Circumferential measurement

32. F8
Fp2
20 % of total length at that line from Fp1 and Fp2 is F7 in Left and F8 in right
Circumferential measurement

33. F8
Fp2
20 % of total length at that line from Fp1 and Fp2 is F7 in Left and F8 in right
Circumferential measurement

34. 20 % of T3 and T4 at same line are T5 and T6 left and right side
Circumferential measurement

35. T6
T4
20 % of T3 and T4 at same line are T5 and T6 left and right side
Circumferential measurement

36. O2
10% from Oz in left is O1 and right is O2
Circumferential measurement

37. O2
10% from Oz in left is O1 and right is O2
Circumferential measurement

38. Para sagittal measurement
Intersection point of the Fp1 to C3 and F7 to Fz is F3 in left.

39. intersection point of the Fp2 to C4 and Fz to F8 is F4 in right
Para sagittal
measurement

40. Intersection point of the C3 and O1 and T5 and Pz is P3 in left
Para sagittal measurement

41. intersection point of the C4 and O2 and T6 to Pz is P4 in right
Para sagittal measurement

42. Extraelectrodesin NIMHANS
T1,T2

43. Extra electrodes in NIMHANS
T1,T2
Line is drawn from tragus to outer cantus to both side

44. Line is drawn from tragus to outer canthus to both side
Extra electrodes in NIMHANS
T1,T2

45. 1/31/3
A point is taken on this line that is 1/3 of total length from tragus to outer canthus
Extra electrodes in NIMHANS
T1,T2

46. 1 cm 1 cm
Point is taken from 1 cm vertical from this point on that horizontal line
Extra electrodes in NIMHANS
T1,T2

47. Extraelectrodesin NIMHANS
T1,T2
1 cm 1 cm
T2 T1
This mark is final for T2 in right side and T1 in left side

48. Extraelectrodesin NIMHANS
F9 &F10

49. F
F
F
P
9
F8
F7
Extra electrodes in NIMHANS
F9 &F10
FZFZ
A line is drawn from F8 to F7 that is passing through Fz

50. F
F
F
P
9
F8
F7
FZFZ
10%10%
Vertical downward a point is taken from F7 and F8 this is 10% of total
measurement from F8 to F7,on each side
Extra electrodes in NIMHANS
F9 &F10

51. F
F
F
P
9
F8
F7
FZFZ
10%10%
Vertical downward a point is taken from F7 and F8 this is 10% of total
measurement from F8 to F7,on each side
Extra electrodes in NIMHANS
F9 &F10

52. F
F
F
P
9
F8
F7
Extraelectrodesin NIMHANS
F9 &F10
FZFZ
10%
F9F10
10%
This final point on each side are F9 and F10 in left and right Respectively