What is the overview of the arterial supply system of the central nervous system?

From the Guidelines

The arterial supply system of the central nervous system is a complex network that includes the internal carotid arteries and vertebral arteries, which form the Circle of Willis at the base of the brain, providing crucial collateral circulation in case of vessel occlusion. The brain receives blood from these two major systems, which work together to provide continuous blood flow to the brain and spinal cord 1.

Key Components of the Arterial Supply System

• The internal carotid arteries and vertebral arteries form the Circle of Willis, a circular anastomosis that includes the anterior communicating artery connecting the anterior cerebral arteries, and posterior communicating arteries linking the internal carotid and posterior cerebral arteries.
• The Circle of Willis gives rise to three pairs of major arteries: the anterior cerebral arteries, middle cerebral arteries, and posterior cerebral arteries, which supply different regions of the brain.
• The brainstem and cerebellum receive blood from the vertebrobasilar system, while the spinal cord is supplied by the anterior spinal artery and paired posterior spinal arteries, supplemented by radicular arteries at various levels.

Variations in Arterial Supply

• The configuration of the circle of Willis is highly variable, with a complete circle present in fewer than 50% of individuals 1.
• The internal carotid artery typically bifurcates into the internal and external carotid arteries at the level of the thyroid cartilage, but anomalous bifurcations may occur up to 5 cm higher or lower 1.
• The length and tortuosity of the internal carotid artery are additional sources of variation, with undulation, coiling, or kinking in up to 35% of cases, most extensively in elderly patients 1.

Clinical Significance

• The arterial supply system of the central nervous system is crucial for providing adequate oxygen and nutrients to the metabolically demanding neural tissue, with the brain alone receiving approximately 15-20% of cardiac output despite comprising only 2% of body weight.
• Understanding the variations in arterial supply is essential for diagnosing and treating cerebrovascular diseases, such as stroke and cerebral vasculitis.

From the Research

Arterial Supply System of the Central Nervous System

The arterial supply system of the central nervous system (CNS) is complex and involves multiple blood vessels that supply oxygen and nutrients to the brain and spinal cord.

• The main arteries that supply blood to the brain include the carotid arteries and the vertebral arteries, which branch off into smaller arteries such as the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery 2.
• These arteries are responsible for supplying blood to different regions of the brain, including the cerebral cortex, basal ganglia, and brainstem.
• The arterial supply system of the CNS is also supported by a network of smaller blood vessels, including arterioles, capillaries, and venules.

Regulation of Blood Flow

The regulation of blood flow to the CNS is critical for maintaining proper brain function.

• Blood flow to the brain is regulated by a variety of factors, including blood pressure, carbon dioxide levels, and neural activity 3, 4.
• The brain has a unique ability to maintain a constant blood flow despite changes in blood pressure, a process known as autoregulation.
• Autoregulation is mediated by a complex interplay of neural, vascular, and metabolic mechanisms that work together to maintain optimal blood flow to the brain.

Clinical Significance

Understanding the arterial supply system of the CNS is important for the diagnosis and treatment of neurological disorders, such as stroke and transient ischemic attack (TIA).

• Stroke and TIA occur when there is a disruption in blood flow to the brain, either due to a blockage or rupture of a blood vessel 5, 6.
• Treatment of stroke and TIA often involves the use of antiplatelet agents, such as aspirin and clopidogrel, to prevent further clotting and improve blood flow to the affected area.
• In some cases, thrombolytic therapy may be used to dissolve blood clots and restore blood flow to the brain.