Angiograms depicting the distribution of two of the cerebral arteries. On the left is the middle cerebral artery of the left hemisphere. This artery supplies blood to the lateral surface of the brain; the left image depicts the left cerebral hemisphere. The image on the right depicts the anterior cerebral artery of the right hemisphere, which supplies blood to the medial surface of the hemisphere.

Introduction:

Stroke (Cerebral Vascular Accident; CVA): Stroke is a general term used to describe virtually any disturbance in cerebral circulation that results in ischemia and anoxia. Another term commonly employed is Cerebral Vascular Accident (CVA). These include occlusion of the arteries by fatty emboli or blood clots, breaks in arteries that produce hemorrhage and ischemia resulting from decreased blood pressure and overall perfusion.

Arterial Supply: Blood is supplied to the brain by three major artery systems: The right and left internal carotid arteries, and the vertebral/basilar system. The carotid arteries supply the anterior two-thirds of the cerebral hemispheres and the vertebral/basilar systems supplies the brainstem and cerebellum and posterior parts of the hemispheres.

Carotid Arteries: As the internal carotid arteries travel upward through each hemisphere, they divide into two branches, the anterior and middle cerebral arteries. The anterior cerebral artery supplies the inferior surface of the frontal lobe and the medial parts of the hemisphere. The middle cerebral artery supplies the basal ganglia, deep white matter and the lateral surface of the hemisphere. The basal ganglia are supplied by small branches of the middle cerebral artery called the lenticulostriatal arteries.

Vertebral/Basilar System: The vertebral arteries run upward through the cervical vertebrae of the neck and enter the skull through the foramen magnum. The two vertebral arteries join and form the basilar artery. The artery supplies the pons, cerebellum and midbrain. As the basilar artery reaches the top of the cerebellum it divides to form the two posterior cerebral arteries. These arteries supply the thalamus, medial surface of the temporal lobes and virtually the entire occipital lobes.

Venous Flow: Blood drains from the brain through shallow and deep systems of venous flow. The surface of the hemispheres are drained by superficial veins that flow into the superior sagittal sinus. The inferior surface of the brain and deep structures are drained by a system that eventually forms the straight sinus. The straight and superior sinuses in the posterior part of the brain join to eventually form the jugular veins in the neck.