Fig. 3

Scatter plots of the anatomical relationship between the limen insulae and the target. In the left panel the location of the target (open circles for the right-, x-marks for the left-, and red dot for the mean location) was plotted on the coordinate axis defined on the axial plane on which the limen insulae (a green dot) was set as the origin. The angle between the right-left axis (i.e., x axis) and the limen insulae-inferior horn vector (gray arrow) is defined as the approach angle on the axial plane (θa). In the right panel the location of the target (open circles for the right-, x-marks for the left-, and red dot for the mean location) was plotted on the coordinate axis defined on the coronal plane on which the limen insulae (green dot) was set as the origin. The angle between the right-left axis (i.e., x axis) and the limen insulae-inferior horn vector (gray arrow) is defined as the approach angle on the coronal plane (θc). The scale is shown in the upper right corner of each panel. The orientation is shown in the upper left corner. Ant. anterior, Inf. inferior, Lat. lateral, Med. medial, Post. posterior, Sup. superior.