Human brain. Coronal anatomical section through a normal healthy brain, passing through the primary motor cortex. The internal structure of the brain is visible, including the grey matter of the cerebral cortex (composed of nerve cell bodies), the white matter (which consists of nerve cell fibres), and lateral ventricles (spaces filled with cerebrospinal fluid). The cerebral cortex is folded, giving a much greater surface area. The primary motor cortex is involved in controlling movement.