The spinal cord is made up of bundles of nerve fibers. It runs down from the brain through a canal in the center of the bones of the spine. These bones protect the spinal cord. Like the brain, the spinal cord is covered by the meninges and cushioned by cerebrospinal fluid.
Internal changes, like body muscle decreases; the size, shape and function that occurs in our body to function in a mature system.(phenotype) >hope that help
