The carotid arteries are the blood vessels that travel from the heart through the neck into your brain. They supply the brain tissue with the oxygen and nutrients it needs to survive and function. Disease of the carotid arteries results from a blockage in them, almost always from thickening and hardening (atherosclerosis) of the arteries. This results in plaque buildup in the arteries. More uncommon carotid artery disorders include carotid dissections, which are tears in the inner lining of the blood vessel, and fibromuscular dysplasia, which can cause narrowing of the artery in the absence of atherosclerosis.