The vertebral artery is a crucial blood vessel that supplies the brain with oxygen and nutrients. It is part of the vertebrobasilar system, responsible for a substantial portion of the brain’s blood flow. Understanding its journey and the areas it nourishes helps clarify its importance in maintaining overall brain function. This network is fundamental for many involuntary and higher-level processes.
The Vertebral Artery’s Path
The vertebral artery originates in the chest, branching off the subclavian artery. Each side of the body has one vertebral artery. From its origin, the artery ascends through the neck, passing through transverse foramina within the cervical vertebrae (C6 to C1).
After traversing the cervical spine, the vertebral artery curves around the first cervical vertebra (atlas) and enters the skull through the foramen magnum. Inside the cranial cavity, these two arteries typically converge. This merger usually occurs at the lower border of the pons, forming the basilar artery.
Direct Supply Regions
Before the two vertebral arteries unite to form the basilar artery, they directly provide blood to several important structures. These direct branches supply the lower parts of the brainstem and portions of the cerebellum, along with the upper spinal cord.
The medulla oblongata, the lowest part of the brainstem, receives blood from direct branches of the vertebral arteries, including the anterior spinal artery and the posterior inferior cerebellar artery (PICA). The medulla oblongata is a critical control center, managing involuntary functions such as breathing, heart rate, and blood pressure. It also plays a role in reflexes like swallowing, coughing, and vomiting. The PICA, which is the largest branch originating directly from the vertebral artery, extends its supply to a significant portion of the cerebellum, specifically its posterolateral area. The cerebellum is an area of the brain essential for coordinating movement, maintaining balance, and assisting in aspects of speech and vision.
The Basilar Artery and Its Contributions
This newly formed artery then continues to ascend, supplying a broad range of brain regions. The basilar artery provides blood flow to the upper parts of the brainstem, including the pons and midbrain. Small vessels called pontine arteries branch directly from the basilar artery to nourish the pons, which is involved in relaying sensory and motor information, regulating breathing, and controlling sleep-wake cycles.
Additionally, the basilar artery gives rise to the anterior inferior cerebellar arteries (AICAs) and the superior cerebellar arteries (SCAs), which further supply the cerebellum. At its upper end, the basilar artery divides into two posterior cerebral arteries (PCAs). These PCAs extend to supply the posterior regions of the cerebrum, including the occipital lobes and the inferomedial surfaces of the temporal lobes. The occipital lobes are specialized for processing visual information, enabling the perception of color, form, and motion. The PCAs also send smaller branches to the thalamus, a brain structure that acts as a relay station for sensory and motor signals, and is involved in consciousness, sleep, and memory.
Why This Supply Matters
The blood supply delivered by the vertebral and basilar arteries is essential for the proper functioning of many vital brain structures. These arteries nourish regions that control fundamental bodily processes such as breathing, heart rate, and consciousness. They also support areas responsible for balance, coordination, and the processing of vision, making their continuous and adequate blood flow indispensable for daily activities and sensory perception.
Any disruption to blood flow in these arteries can have significant consequences due to the critical functions of the brain regions they supply. The intricate network of vessels, including the vertebral and basilar arteries, ensures that the brain receives a steady supply of oxygen and nutrients. While other arterial systems, such as the carotid arteries, supply different parts of the brain, the vertebrobasilar system is uniquely responsible for the posterior circulation. This specialized supply underscores its importance for maintaining a wide range of neurological functions, from basic survival mechanisms to complex sensory experiences.