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The circle of Willis (also called Willis' circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures in reptiles, birds and mammals, including humans. [1] It is named after Thomas Willis (1621–1675), an English physician. [2]
Willis was a pioneer in research into the anatomy of the brain, nervous system and muscles. His most notable discovery was the "Circle of Willis", a circle of arteries on the base of the brain. Willis's anatomy of the brain and nerves, as described in his Cerebri anatome of 1664, is minute and elaborate.
The basilar artery (U.K.: / ˈ b æ z. ɪ. l ə /; [1] [2] U.S.: / ˈ b æ s. ə. l ər / [3]) is one of the arteries that supplies the brain with oxygen-rich blood.. The two vertebral arteries and the basilar artery are known as the vertebral basilar system, which supplies blood to the posterior part of the circle of Willis and joins with blood supplied to the anterior part of the circle of ...
Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries (and less commonly veins) in order to evaluate them for stenosis (abnormal narrowing), occlusions, aneurysms (vessel wall dilatations, at risk of rupture) or other abnormalities.
In case of narrowing of other arteries of the circle of Willis or the arteries supplying the circle, the anterior communicating artery can provide a way to supply blood to the opposite (affected) side of the circle. This can often preserve the cerebral blood supply well enough to avoid the symptoms of ischemia. [7]
Circle of Willis with the most common locations of ruptured aneurysms marked. Most cases of SAH are due to trauma such as a blow to the head. [1] [21] Traumatic SAH usually occurs near the site of a skull fracture or intracerebral contusion. [22] It often happens in the setting of other forms of traumatic brain injury.
Added labels: Recurrent artery of Heubner and posteromedial central arteries, Circle of Willis, A1, A2, P1, P2. Correct arising for labyrinthine arteries. Use of layers.
Although they may occur in any blood vessel, particularly lethal examples include aneurysms of the circle of Willis in the brain, aortic aneurysms affecting the thoracic aorta, and abdominal aortic aneurysms. Aneurysms can arise in the heart itself following a heart attack, including both ventricular and atrial septal aneurysms.