Carotid Arteries
The carotid arteries are the four principal arteries of the neck and
head. They have two specialized regions: the carotid sinus, which
monitors the blood pressure, and the carotid body, which monitors the
oxygen content in the blood and helps regulate breathing. The internal
carotid arteries enter the skull to supply the brain and eyes. At the base
of the brain, the two internal carotids and the basilar artery join to
form a ring of blood vessels called the "circle of Willis." The external
carotid arteries have several branches which supply the tissues of the
face, scalp, mouth and jaws.