There are at least two reasons to become familiar with the details of the blood supply to the central nervous system. The first is that the larger blood vessels may be visualized radiographically by injecting dye into the arterial system and obtaining films at frequent intervals during the first seconds afterwards. In part, these studies (arteriograms) reveal the state of the arterial and venous systems, i.e., they can demonstrate the occlusion of a vessel, the presence of an aneurysm, etc. Of even greater significance, the blood vessels serve as markers, showing the position of the brain tissue upon which they run. Thus, the shift of a midline vessel away from the midline tells us that there must be an expanding lesion on one side of the brain. But, obviously, you won't be able to pick up these displacements unless you know what the normal position of the blood vessels is. The second reason to be familiar with the blood supply has to do with being able to understand the clinical syndromes associated with the occlusion of various vessels. For example, you can either memorize the constellation of findings which may result when the posterior inferior cerebellar artery is occluded or you can remember the general region supplied by that vessel and reason out the features of the syndrome. We think the latter approach is the rational one.

     In this lab manual, we have encouraged you to build your knowledge of the central nervous system on the framework of relatively few standard views of the brain and spinal cord. The goal of this module is to lay out the blood supply on this same group of figures.