Peripheral Nerves are outside the brain and spinal cord and fibers are covered with a myelin sheath and neurilemma. Which statement is true?

• A. They are inside the brain and spinal cord.
• B. Outside the brain and spinal cord and fibers are covered with a myelin sheath and neurilemma.
• C. They only carry motor signals.
• D. They are not connected to the spinal cord.

Answer: (B)

Peripheral nerves are part of the peripheral nervous system, so they lie outside the brain and spinal cord. Their axons can be insulated by a myelin sheath produced by Schwann cells, and the outermost layer around the myelin is the neurilemma (neurolemma). This combination—location outside the CNS plus a myelin sheath with a neurilemma—is what the statement is describing. The CNS uses oligodendrocytes to wrap myelin and does not have a neurilemma, so the other ideas (being inside the brain/spinal cord, carrying only motor signals, or having no connection to the spinal cord) don’t fit.