Which arterial vessel does not contribute to the formation of the circle of Willis ?
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Answer: C. Posterior – inferior cerebrat
Explanation
The posterior inferior cerebellar artery originates directly from the vertebral artery trunk. It supplies the cerebellum and lateral medulla oblongata instead of forming the cerebral circle. The circle of Willis is exclusively formed by internal carotid and basilar artery branches. The circle of Willis is an anastomotic vascular ring at the base of the brain. It ensures collateral blood flow between the anterior and posterior cerebral circulations. Key contributing vessels include the internal carotids and the terminal basilar artery.
Anatomical variations in the circle of Willis affect vulnerability to cerebral aneurysms. Stroke symptoms often depend on whether blockages occur inside or outside this arterial ring. Neurosurgeons must map these major vessels carefully before performing intracranial procedures. The anterior cerebral artery contributes directly to the anterior portion of the circle. The posterior communicating artery bridges the anterior and posterior cerebral circulations. Excluding the posterior inferior cerebellar artery correctly identifies it as a peripheral branch.
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