Original: Aneurysms most commonly occur in arteries at the base of the brain ( the circle of Willis ) and in the aorta ( the main artery coming out of the heart , a so-called aortic aneurysm ) .
Simplified: Aneurysms usually happen in arteries at the base of the brain and in the aorta ( the main artery coming out of the heart ) - this is an aortic aneurysm .