The brain receives its blood supply from two primary sources: the internal carotid arteries and the vertebral arteries.
Here's a breakdown of how this process works:
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Internal Carotid Arteries: These arteries are the main suppliers of blood to the front of the brain. They originate in the neck where the common carotid arteries split. Each internal carotid artery branches into two major cerebral arteries:
- Anterior Cerebral Artery (ACA): Supplies blood to the frontal lobe and the upper parts of the parietal lobe.
- Middle Cerebral Artery (MCA): Supplies blood to a large portion of the lateral surfaces of the frontal, parietal, and temporal lobes. This is the most commonly affected artery in strokes.
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Vertebral Arteries: These arteries supply blood to the back of the brain. They originate from the subclavian arteries and travel up through the vertebrae in the neck, eventually merging to form the basilar artery.
- Basilar Artery: This artery provides blood to the brainstem, cerebellum, and parts of the cerebrum. It branches into the posterior cerebral arteries.
- Posterior Cerebral Arteries (PCA): Supply blood to the occipital lobe (responsible for vision) and the lower parts of the temporal lobe.
The Circle of Willis: This is a crucial network of arteries located at the base of the brain. It connects the anterior and posterior cerebral circulation systems. The Circle of Willis acts as a safety mechanism, ensuring that if one of the main arteries is blocked or narrowed, blood can still reach all parts of the brain through alternative routes.
In summary, the brain relies on a complex and interconnected network of arteries, primarily the internal carotid and vertebral arteries, to deliver the oxygen and nutrients it needs to function properly. The Circle of Willis provides a critical backup system to maintain blood flow in case of arterial blockage.
