Cerebral circulation
From Free net encyclopedia
Cerebral circulation refers to the blood vessels in the brain. Arteries carry blood to the brain, and veins carry it away, back to the heart. The cerebral blood vessels are responsible for cerebral blood flow, the amount of blood within the skull.
Cerebral Arteries
There are four cerebral arteries. The two largest are the two internal carotid arteries, the left and right branches of the common carotid arteries in the neck which enter the skull, as opposed to the external carotid branches which supply the facial tissues. The two smaller arteries are the vertebral arteries, which branch from the subclavian arteries which primarily supply the shoulders, lateral chest and arms.
Within the cerebral vault, 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 arteries, within and along the floor of the cerebral vault, are interconnected via the anterior communicating artery. Additionally, both internal carotid arteries are interconnected with the basilar artery via bilateral posterior communicating 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 arteries and basilar artery along the floor of the cerebral vault, providing blood to tissues that would otherwise become ischemic.
Cerebral Veins
The cerebral veins join to form a central sagittal vein, which flows under the top middle portion of the cerebral vault, posteriorly and inferiorly, and divides to form the two jugular veins. In the neck, the jugular veins parallel the upward course of the carotid arteries and drain blood into the vena cava.