6. Brainstem and cranial nerves

The brainstem is the portal between the brain and the spinal cord, through which signals pass in both directions. The brainstem also acts as the ‘spinal cord’ for the cranial senses and muscles. Various biogenic amines are produced in the brainstem, which regulate mood, vigilance, attention and initiative (see above). Ten of the twelve cranial nerves lead to or from the brainstem. Unlike the spinal cord nuclei, they are usually controlled by both cortex hemispheres. The brainstem performs various vital and autonomic motor system functions. Failure of the brainstem gives rise to a life-threatening condition. An EMV score provides an indication of brainstem function. Discrete failure can be associated with a wide variety of syndromes, in the context of which the problem can be localized on the basis of the combined clinical symptoms.