Carotid stenosis is a narrowing or constriction of the inner surface (lumen

Lumen (anatomy)

A lumen in biology is the inside space of a tubular structure, such as an artery or intestine...

) of the carotid artery

Carotid artery

Carotid artery can refer to:* Common carotid artery* External carotid artery* Internal carotid artery...

, usually caused by atherosclerosis

Atherosclerosis

Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...

 .
The carotid artery is the large artery whose pulse can be felt on both sides of the neck under the jaw.On the right side it starts from the brachiocephalic trunk (a branch of the aorta) as the common carotid artery, and on the left side the common carotid artery comes directly off the aortic arch.