Circle of Willis
Transcript of Circle of Willis
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Circle of WillisCircle of Willis((arterial circle, circulus arteriosusarterial circle, circulus arteriosus))
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The arterial circle, described by Thomas Willis in 1664, is an important polygonal anastomosis between the four arteries that supply the brain: the two vertebral and the two internal carotid arteries.
It is formed by the posterior cerebral, posterior communicating, internal carotid, anterior cerebral and anterior communicating arteries.
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The circle forms an important means of collateral circulation in the event of obstruction of a major vessel. Variations in the size of the vessels that constitute the circulus are very common.
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Angiographic view
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Carotid angiogramCarotid angiogram
Carotid siphon
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Vertebral angiogramVertebral angiogram
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Showing the origins of main arteries
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circle of Willis in situ