Volume 65 No 6  Cover Story

The configuration of anterior bend of carotid siphon (green segment in left figure). The configuration is cagegorized into angled (V, < 20°; left upper of right figure) and non-angled (C, U, and S) types depending on morphology and measured angles between two lines traced through the midpoints of the diameters of each straight segment (white dotted lines). C-type (≥20°; right upper of right figure), U-type (≥-20°, <20°; left lower of right figure). S-type (<-20°, right lower of right figure).