What are cerebral aneurysms?

Grapes on a vine: Cerebral aneurysms are out pouch rings of the blood vessels along their normal course. Blood vessels should generally resemble drinking straws which gradually taper as they reach their end. In aneurysms, the arteries bulge out, sometimes very prominently (looking much like grapes on a vine) and posing a substantial risk of rupture because of the stress this places on the vessel.

Arterial: Intracranial arteries to the brain develop outpouching or enlargement as saccular or fusiform aneurysms. They are the arteries to the brain-cerebrum. If they leak or rupture the cause subarachnoid bleeding, headache, stroke etc.