What constitutes the central and peripheral nervous systems? How are the components of the central nervous system protected?

(N/A) The central nervous system $(CNS)$ is composed of the brain and the spinal cord.
The peripheral nervous system $(PNS)$ consists of all the nerves that branch out from the $CNS$ and connect to the rest of the body,including cranial nerves and spinal nerves.
The components of the $CNS$ are protected as follows:
$1$. The brain is protected by a bony box called the cranium (brain box),which contains cerebrospinal fluid for shock absorption.
$2$. The spinal cord is protected by the vertebral column (backbone).