N1A6

Internal carotid artery aneurysm (red) registered to normal (blue). Please notice the sharp bend, in the aneurysm artery, exactly where the aneurysm developed. Also, please notice that this sharp bend is only noticeable with large magnification and from certain angles. In 1979, Rhoton introduced three rules relating to the anatomy of saccular aneurysms. First, cerebral aneurysms arise at a branching site on the parent artery. Second, “saccular aneurysms arise at a turn or a curve in an artery, on the convex, not concave, side of the curve”. Third, “saccular aneurysms point in the direction the blood would have gone if the curve at the aneurysm site were not present”.