Fig. 43-18. The chief arteries to the brain, as seen on angiography. The main vessels are shaded. A and B, Carotid arteriograms in lateral and anteroposterior projections. The internal carotid pierces the dura at d. The inset shows, in left lateral view, the numbered portions of the internal carotid artery. C and D, Vertebral arteriograms in lateral and half-axial (fronto-occipital) projections. In C, a is the site of the foramen transversarium of the atlas, b is the foramen magnum, and c is at the junction of the right and left vertebral arteries, i.e., the beginning of the basilar artery. AC, anterior cerebral artery; MC, middle cerebral artery; PC, posterior cerebral artery. (Based largely on Greitz and Lindgren.) Click for high resolution image.