Vascularization of the brain and spinal cord

In this introductory chapter, the vascularization of the brain and the spinal cord are discussed with examples of the clinical syndromes of arterial or venous occlusions. The English terms of the Terminologia Neuroanatomica are used throughout. A further subdivision of the segments of the major brain arteries has been included. The same holds for the cerebral veins. The advent of neuroimaging has allowed a more precise clinicopathological correlation of ischaemic lesions and infarcts on computerized tomography (CT) and magnetic resonance imaging (MRI). For a more precise assessment of the vessels involved, knowledge of the arterial territories and their variations is needed. Atlas sections of the arterial territories of the human cerebral hemispheres, the cerebellum and the brain stem are presented in Sects. 2.5, 2.11 and 2.12, respectively. Most cerebral arteries have anastomoses that can partially supply neighbouring brain areas. Within limits, even an insufficient blood supply to the brain via the internal carotid and vertebral arteries may be compensated by anastomoses from the facial and the superficial temporal arteries with the ophthalmic artery and by a reversal of the direction of the blood flow of the ophthalmic artery into the internal carotid. Leptomeningeal anastomoses between the three cerebral arteries and between cerebellar arteries also exist. However, despite all the anastomoses between brain arteries, the sudden occlusion of a large artery will lead to ischaemic brain infarction (see Sect. 2.7). The clinical symptoms of an arterial occlusion depend on the neurofunctional systems affected and particular syndromes have been defined. Several examples, illustrated by imaging and postmortem data, are presented as Clinical cases.