<prompt> A 9-year-old boy is diagnosed with multiple sclerosis MS. Which of the following nervous structures would most likely be affected by this disease?Trigeminal ganglionSuperior cervical ganglionOptic nerveFacial nerve  <response>: Multiple sclerosis affects only axons in CNS spinal cord and brain that have myelin sheaths formed by oligodendrocytes. Optic nerve is considered to be pa of CNS, as it is derived from an outpouching of diencephalon. All other nervous structures are in the PNS and have their myelin sheaths formed by Schwan cells 