Multiple Sclerosis (MS) Practice Test

MS is an autoimmune attack on the myelin of the central nervous system, so the tissue most affected is the white matter of the CNS. The white matter houses the long, myelinated axons whose rapid, saltatory conduction relies on intact myelin produced by oligodendrocytes. When this myelin is damaged, conduction slows or fails along those tracts, producing the characteristic neurologic deficits of MS. Peripheral nerves aren’t the primary target because their myelin is produced by Schwann cells in the peripheral nervous system, not by CNS oligodendrocytes, so demyelination there is not the hallmark of MS. Gray matter can be involved, and meninges can be involved in other conditions or later disease processes, but the hallmark tissue MS most severely affects is CNS white matter.