Central nervous system: the brain and the spinal cord. Spinal cord: a long, thin collection of nerve cells attached to the back of the brain and running the length of the spinal column. Nerve: a bundle of fibers that transmits information between the central nervous system and the body"s sense organs, muscles and glands. Peripheral nervous system: the cranial and spinal nerves, that part of the nervous system peripheral to the brain and spinal cord. Cranial nerve: a bundle of nerve fibers attached to the base of the brain; conveys sensory info from the face and head and carries messages to muscles and glands. Spinal nerve: a bundle of nerve fibers attached to the spinal cord; conveys sensory info from the body and carries messages to muscles and glands. Brain stem: the stem of the brain, including the medulla, pons, and midbrain.