The neck houses the most important set of blood vessels, serving as the main conduit for oxygenated blood traveling from the heart to the brain. This pathway delivers the continuous supply of fuel necessary for all cognitive and regulatory functions. The volume of blood flow needed requires these arteries to be significantly larger than those supplying other areas of the head. Protecting the health of these vessels is paramount, as any interruption to this flow can have immediate and severe consequences.
Identifying the Common Carotid Artery
The main artery in the neck is the Common Carotid Artery (CCA), a pair of major blood vessels, one on each side. Each CCA originates from the chest, ascending vertically through the neck within a protective sheath of connective tissue. It is located relatively deep, running alongside the windpipe and voice box, partially shielded by the large sternocleidomastoid muscle. The CCA is the primary site where a healthcare professional can quickly assess a person’s pulse in the neck. Placing fingers gently on the side of the neck allows one to feel the rhythmic expansion and recoil of this powerful vessel. As it travels upward, the Common Carotid Artery divides into two distinct branches near the upper border of the thyroid cartilage. This split, known as the carotid bifurcation, gives rise to the Internal Carotid Artery and the External Carotid Artery, separating the blood supply for the brain from the blood supply for the face and scalp.
The Carotid System’s Role in Brain Function
The two resulting branches of the common carotid artery serve entirely different purposes in the head and neck.
Internal and External Carotid Arteries
The Internal Carotid Artery (ICA) proceeds upward without giving off any branches in the neck, entering the base of the skull to supply the brain. Once inside the cranium, the ICA delivers the vast majority of blood to the brain’s anterior and middle sections. This blood flow supports the large cerebral hemispheres, which are responsible for high-level functions like thought, memory, and voluntary movement. The External Carotid Artery (ECA), in contrast, remains outside the skull, branching extensively to supply the face, scalp, tongue, and neck structures.
The Carotid Sinus
The carotid bifurcation contains a specialized, slightly dilated area called the carotid sinus. This sensory organ contains baroreceptors, which are nerve endings sensitive to pressure changes within the artery. These baroreceptors constantly monitor the blood pressure heading toward the brain. If blood pressure rises or falls, the carotid sinus sends signals to the brainstem to initiate adjustments in heart rate and blood vessel tone, helping to regulate and stabilize blood flow to the brain.
The Vertebral Arteries and Posterior Circulation
While the carotid system is the most prominent, a second pair of arteries contributes to the brain’s circulation: the Vertebral Arteries. These vessels originate from the subclavian arteries in the chest and follow a protected pathway through the neck. They ascend through tunnels, called transverse foramina, within the bony processes of the cervical vertebrae. This specialized bony channel shields the arteries from compression and damage during neck movement. The two vertebral arteries continue their upward path until they enter the skull at the base of the head, where they merge to form the Basilar Artery. This fusion marks the beginning of the posterior circulation system. The posterior circulation supplies the rear portion of the brain, including the cerebellum and the brainstem, which manages automatic, life-sustaining functions such as breathing and heart rate.
Understanding Arterial Plaque and Stroke Risk
The health concern most closely associated with the neck arteries is Carotid Artery Disease, also known as carotid stenosis. This condition involves the gradual accumulation of fatty deposits, cholesterol, and cellular debris—collectively called plaque—within the artery walls, a process known as atherosclerosis. This plaque buildup causes the artery to narrow, restricting the volume of blood that can flow to the brain.
This narrowing can lead to an ischemic stroke in two primary ways. The first is that the plaque can grow so large that it completely blocks the Common or Internal Carotid Artery, cutting off blood flow to a large section of the brain.
The second mechanism is when the surface of the plaque ruptures, triggering the formation of a blood clot. A fragment of this clot or a piece of the plaque can break off and travel downstream into the smaller arteries within the brain, causing an embolization. When this debris lodges in a smaller vessel, it instantly blocks the blood supply, causing brain cells in that area to die from lack of oxygen.
Sometimes, a temporary blockage occurs, causing a Transient Ischemic Attack (TIA). This is often called a “mini-stroke,” and it serves as an urgent warning sign of high stroke risk.