Which structure would be unaffected by the peripheral nervous system?

For the answer to the question above, the peripheral nervous system governs all structures outside the brain and spinal cord. Peripheral nerves branch from the spinal cord through the foramen transversarium of each vertebrae. I suppose the structure it would not affect is the brain itself since cranial nerves are responsible for brain activity. Also, the spinal cord would also be unaffected since it is just a cylindrical bundle of nerve fibers that allow the connection of the peripheral nerves to the brain.