Windows and Receivers

The Story

By now Stina’s nervous-system chart read like a tour of the headRounded proximal end that fits into the acetabulum of the hip bone.: face pain here, hearing loss there, the old fevers traced to a structure deepAway from the surface of the body. in the brain. To make sense of which nerves her disease had touched — and which it had spared — she needed the whole roster: the special senses and the twelve cranial nervesNerves that arise from the brain and control head and neck functions. that serve them. Only against that map do her two affected nerves snap into place.

The special senses — sight, hearing, smell, taste, and balance — are served largely by the cranial nerves, twelve paired nerves emerging from the brain. The eye, the “window,” focuses light through the cornea and lens onto the retina, whose photoreceptors send vision down the optic nerve (CN II). Smell travels on CN I, vision on CN II, eye movementA fundamental property of life involving motion of the body or its parts. on III/IV/VI; the trigeminal nerve (CN V) carries facial sensation; the facial nerve (CN VII) carries taste and moves the face; and the vestibulocochlear nerve (CN VIII) carries hearing and balance from the inner ear. Two of these are now central to Stina’s story: CN V, the source of her trigeminal neuralgia, and CN VIII, the nerve of the cochlea she is slowly losing. Surveying the full set shows that her symptomsSubjective experiences reported by the patient (e.g., nausea, fatigue). aren’t random — they cluster in specific cranial nerves of an inflamed nervous system, while others (her vision, for now) remain spared.

From Stina’s chart: Stina has now collected symptoms across face sensation and hearing. This page surveys the special senses and the cranial nerves, placing her two affected nerves in the full set.