fig 4.

Parasagittal line. Limited anatomic diversity is seen on composite tracings from four different subjects. Labels as in figures 1 and 2.

A, 27-year-old man. The anatomic alignment is stereotypical.

B, 42-year-old woman. The parasagittal line traverses the midpoint of a double arc epsilon-shaped hand-motor area (small asterisks) on the right. On the left, the medial edge of the single ω-shaped hand-motor area (large asterisk) lies medial to the parasagittal line, while the postcentral parenthesis (open arrow) lies on the line.

C, 13-year-old boy. Unusually deep extension of the right pars marginalis (emphasized in black, arrowheads) displaces the right pars deflection onto the parasagittal line. The precentral notches (solid black circles) and hand-motor areas (asterisks) align well with the parasagittal line. The arrows outside the brain contour at 5 o'clock and 7 o'clock indicate notches in the brain contour along the IOS, corresponding to the bony occipital ridges (see fig 5).

D, 81-year-old woman. Very deep invagination of the partes marginales displace the pars deflections onto the parasagittal line bilaterally