False-colour nuclear magnetic resonance (NMR) image of a mid-sagittal section through a human head, showing structures of a normal brain, airways (black) & facial tissues. The heavily- folded cerebral cortex (the grey matter), which forms the outer part of the cerebrum, appears red with a blue outline. Beneath it at right appears the feathery outline of the cerebellum. Immediately to the left of the cerebellum (in orange) are the structures of the brainstem, an enlarged extension of the spinal cord. The uppermost bones of the neck are seen to the left of the spinal cord. The cerebro-spinal fluid that surrounds the brain & spinal cord appears black.