False-colour nuclear magnetic resonance (NMR) image of a mid-sagittal section through a human head, showing structures of a normal brain, airways & facial tissues. The heavily-folded cerebral cortex (the grey matter), which forms the outer part of the cerebrum, is coloured green, yellow & red. Beneath it at right appears the feathery outline of the cerebellum. Immediately to the left of the cerebellum (in yellow/red) is 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 airway of the throat & cerebro-spinal fluid surrounding the brain & spinal cord appear black.