The nervous system of vertebrates (including humans) constitutes the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system consists of the brain and spinal cord. The peripheral nervous system (PNS) connects the central nervous system (CNS) to sensory organs (such as the eye and ear), other organs of the body, muscles, blood vessels and glands.

CNS is more protected as its main line of defence is the bones of the skull and spinal column, which create a hard physical barrier to injury. Brain in protected by cranium and spinal cord is protected by a cylindrical like column.

Explanation: Brain lies inside a bony box, called cranium while the spinal cord lies within the vertebral column or backbone, such bony structures protect them from mechanical injury and shock. Inside these bony structures lie a series of layers of tissue referred to as meninges. Also cerebrospinal fluid present in the brain and spinal cord serves as a pad to cushion the central nervous system from shock.