carotid artery
Meaning of carotid artery: Narrowing here is one of the more treatable roads to stroke, which is why neck vessels are imaged after brief neurological symptoms.
Definition of carotid artery
The carotid arteries are the large paired vessels of the neck that carry blood from the heart toward the head. One runs on each side, and each common carotid divides partway up the neck into an internal branch supplying the brain and eyes and an external branch supplying the face, scalp and tongue. The pulse felt beside the windpipe is the common carotid.
Where does each carotid run?
The two common carotids do not begin in the same place. The right one branches from a short trunk coming off the aortic arch, while the left one arises from the arch directly, making it the longer of the pair. Each then climbs the front of the neck alongside the windpipe and the voice box, sheltered beneath the broad muscle that runs from behind the ear down to the collarbone, and divides at roughly the level of the upper voice box. At that fork sits a slight widening called the carotid sinus, whose wall is packed with sensors that report blood pressure back to the brain. Beside it lies the carotid body, a small cluster of cells that samples oxygen and carbon dioxide in passing blood and helps set the rate of breathing.
What does each branch supply?
| Branch | What it feeds |
|---|---|
| Internal carotid | Passes into the skull and supplies the front and middle of the brain, together with the eye |
| External carotid | Stays outside the skull and supplies the face, scalp, tongue, jaw, and thyroid gland |
The internal carotid gives off no branches at all in the neck, which is one way it is told from its neighbor during surgery or on a scan. Inside the skull it joins the vessels arriving up the back of the neck to form a ring at the base of the brain, an arrangement that lets blood cross from one side to the other if one route is interrupted. How complete that ring is differs a great deal from person to person, which is part of why identical blockages cause very different amounts of damage.
Why are these vessels linked to stroke?
They deliver the larger share of the blood reaching the brain, and the fork where they divide is a favored site for plaque to build up in the wall of the artery. Blood swirls where a vessel splits, the lining there is more easily injured, and fatty deposits collect by the same process that narrows the heart's own vessels in coronary artery disease. Two consequences follow. The channel can narrow enough to limit flow, and, more commonly, a fragment of plaque or a clot forming on its roughened surface can break loose and lodge in a smaller vessel downstream. Ultrasound of the neck is therefore a routine step after a stroke or after a brief episode of weakness, slurred speech, or loss of vision in one eye.
Used in a sentence
Ultrasound of the carotid artery was ordered to evaluate for narrowing after the patient's transient neurological symptoms.
Good to know
The carotid artery, which carries blood toward the brain, is a distinct structure from the nearby jugular vein, which carries blood away from the head, though the two are sometimes confused given their close proximity in the neck.
Word origin
Where “carotid artery” comes from
From Greek karotides, related to karoun, meaning to stupefy, reflecting an ancient observation that compressing these arteries could induce drowsiness or loss of consciousness.