The Carotid Artery carries Blood From the Aortic Arch to the Head (face and brain skull etc ) Everyne has 2 Carotid arteries on either side of the Neck to just behind the ear . an Anuerysm is a seperation of the 3 Layers in any artery (this case obviously The Carotid.. the Inner (Intima) the Media (Middle) and THe Adventia (adventure >Outside) the outter and inner layers are denser while the middle is THICKER and less dense Made of soft Colligen the Alkalyd Blood can burn its way through the wall (s) AN Anuerysm is bulgeing cause by Blood getting trough the Intima and into the softer media Keep in mind the anuerysm is 3 dimensional and Your Mind is looking at it in 1 dimension.... what causes any anuerysms ? Can be High blood pressure and stress , genetics Disease (syphillis) is known... stress , poor diet cholesterol becoming Hardened and tearing at the walls of a vessle... While they are "similar" to the layperson as an embolism (air or gas bubble) or Blood clot ( Plaque or Goop broken away and getting stuck as the vessle gets smaller the anuerysm can change the blood flow can Blood any flow BUT also can Burst the vessle. In the Case of The Carotid a blockage or Burst vessel can cause Extrime headache Pain (migraine +++) LOSS of conscienceness , loss of eyesight temporary or Perminantly Loss of Motor skills and Loss of all or any Bodily functions either temp or Perminantly depending on how extensive the damage.... quite serious