The neck serves as the primary circulatory corridor, channeling oxygen-rich blood from the torso to the entire head structure. This region is the sole circulatory bridge connecting the heart’s pumping action to the brain’s enormous metabolic demands. Uninterrupted flow through this channel is necessary to maintain consciousness and neurological function, given that brain tissue cannot store oxygen or glucose. Specialized arterial pathways ascend through the neck to ensure this continuous delivery of blood. These vessels are organized symmetrically to provide reliable supply to the brain and the external structures of the face and scalp.
Identifying the Four Major Arteries
The direct answer to how many major arteries travel through the neck to supply the brain is four. These four vessels are classified into two distinct pairs: the Common Carotid Arteries and the Vertebral Arteries. One of each pair runs on the left and right sides of the neck. These four are the primary pathways that deliver the vast majority of blood to the brain.
The Common Carotid Arteries are situated toward the front of the neck, where their pulsations are readily felt. The Vertebral Arteries, in contrast, follow a more protected route, traveling deep within the cervical spine. Both pairs originate from larger vessels in the chest, ensuring balanced blood flow to the head. This dual-system arrangement provides circulatory redundancy, meaning if one pathway experiences a blockage, the others can potentially compensate.
The Carotid Path and Destination
The Carotid system consists of the two Common Carotid Arteries that ascend through the front of the neck. At the level of the thyroid cartilage, roughly around the fourth cervical vertebra, each Common Carotid vessel divides. This bifurcation creates two distinct branches: the Internal Carotid Artery (ICA) and the External Carotid Artery (ECA).
Internal Carotid Artery (ICA)
The ICA is the principal supplier of the forebrain, delivering blood to the majority of the cerebral hemispheres. This vessel enters the skull through a specialized opening called the carotid canal. It does not branch out until it reaches the intracranial space, where it contributes to a circulatory ring at the base of the brain, ensuring widespread cerebral perfusion.
External Carotid Artery (ECA)
The ECA remains outside the skull and focuses its supply on the superficial and external structures of the head. It branches extensively in the neck and face, providing necessary blood flow to the tongue, face, scalp, and surrounding tissues. These branches include the facial artery and the superficial temporal artery. The ECA is responsible for the non-brain structures of the head and neck, complementing the ICA’s role in cerebral supply.
The Vertebral Path and Destination
The two Vertebral Arteries follow a protected path, making them distinct from the Carotid system. These vessels typically originate from the subclavian arteries, which are located beneath the collarbones. They ascend vertically through the neck, traveling through the transverse foramina—bony canals found within the cervical vertebrae.
This sheltered route through the bones provides protection, but it also makes the vessels susceptible to injury from extreme head or neck movements. The arteries pass through the foramina from the sixth cervical vertebra (C6) up to the first (C1). They then curve before entering the skull through the foramen magnum, the large opening at the base of the cranium.
Once inside the skull, the two Vertebral Arteries join together to form a single vessel known as the Basilar Artery. This convergence happens at the level of the brainstem. The resulting Basilar Artery supplies the posterior portion of the brain, including the brainstem, which controls basic life functions, and the cerebellum, which coordinates movement and balance.