Cerebral circulation
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2007-11-23T12:44:33Z
LennartVerhagen
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[[Image:Gray516.png|thumb|right|300px|Inferior aspect of the human brain showing the arterial pattern]]
'''Cerebral circulation''' refers to the movement of [[blood]] through the network of [[blood vessel]]s supplying the [[brain]]. The [[artery|arteries]] deliver oxygenated blood, [[glucose]] and other nutrients to the brain and the [[vein]]s carry deoxygenated blood back to the [[heart]], removing [[carbon dioxide]], [[lactic acid]], and other metabolic products. Since the brain is very vulnerable to compromises in its blood supply, the cerebral circulatory system has many safeguards. Failure of these safeguards results in [[cerebrovascular accident]]s, commonly known as ''strokes''. The amount of blood that the cerebral circulation carries is known as [[cerebral blood flow]].
The following description is based on idealized human cerebral circulation. The pattern of circulation and its [[anatomical nomenclature|nomenclature]] vary between organisms.
==Cerebral arteries==
There are four cerebral [[arteries]]. The largest are the two [[internal carotid artery|internal carotid arteries]], the left and right branches of the [[common carotid artery|common carotid arteries]] in the neck which enter the skull, as opposed to the [[external carotid artery|external carotid]] branches which supply the facial tissues. The two smaller arteries are the [[vertebral artery|vertebral arteries]], which branch from the [[subclavian artery|subclavian arteries]] which primarily supply the shoulders, lateral chest and arms.
Within the [[cranium]], which houses the brain, the two vertebral arteries fuse into the [[basilar artery]], which is located underneath, and primarily supplies, the brainstem.
Both [[internal carotid]] [[artery|arteries]], within and along the floor of the cerebral vault, are interconnected via the [[anterior communicating artery]]. Additionally, both [[internal carotid artery|internal carotid arteries]] are interconnected with the basilar artery via bilateral [[posterior communicating]] [[artery|arteries]].
The [[Circle of Willis]], long considered to be an important anatomic vascular formation, provides backup circulation to the brain. In case one of the supply arteries is occluded, the [[Circle of Willis]] provides interconnections between the [[internal carotid]] [[artery|arteries]] and [[basilar artery]] along the floor of the cerebral vault, providing blood to tissues that would otherwise become [[ischemic]].
==Cerebral venous drainage==
The venous drainage of the cerebrum can be separated into two subdivisions: superficial and deep. The superficial system is composed of [[dural venous sinuses]], which have wall composed of dura mater as opposed to a traditional vein. The dural sinuses are, therefore located on the surface of the cerebrum. The most prominent of these sinuses is the [[Superior sagittal sinus]] which flows in the sagittal plane under the midline of the cerebral vault, posteriorly and inferiorly to the [[torcula]], forming the [[Confluence of sinuses]], where the superficial drainage joins with the sinus the primarily drains the deep venous system. From here, two [[transverse sinuses]] bifurcate and travel laterally and inferiorly in an S-shaped curve that form the [[sigmoid sinuses]] which go on to form the two [[jugular vein]]s. In the neck, the [[jugular vein]]s parallel the upward course of the [[carotid arteries]] and drain blood into the [[vena cava]]. The deep venous drainage is primarily composed of traditional veins inside the deep structures of the brain, which join behind the midbrain to form the [[Vein of Galen]]. This vein merges with the [[Inferior sagittal sinus]] to form the [[Straight sinus]] which then joins the superficial venous system mentioned above at the [[Confluence of sinuses]].
==See also==
*[[Cerebral blood flow]]
*[[Cerebral perfusion pressure]]
==External links==
* [http://www.hemodynamic.com Computer Model of the Cerebral Circulation for Training and Education].
* [http://sky.bsd.uchicago.edu/lcy_ref/synap/brainblood.html Cerebral circulation]
[[Category:Neurology]]
[[Category:Cardiology]]
[[Category:Radiology]]
{{neuroscience-stub}}
[[de:Blutversorgung des Gehirns]]