Central Nervous System (CNS): It is hollowed part of nervous system that lies along the mid - dorsal part of the body. It has two parts, brain (located in the head) and spinal cord (located in the trunk).
Peripheral Nervous System (PNS) : It is solid lateral part of nervous system that develops from CNS and connects different parts of the body with CNS. Peripheral nervous system has two components, voluntary and involuntary. Voluntary peripheral nervous system is under the control of will. It consists of cranial nerves from brain and spinal nerves from spinal cord. Involuntary peripheral nervous system works independent of will. It develops from some cranial and spinal nerves. Involuntary peripheral nervous system is also called autonomic nervous system. It has two parts sympathetic (for emergency) and parasympathetic (for moderation). They control the functioning of various internal body parts.
Protection of Brain : Brain box or Cranium.
Protection of Spinal Cord : Vertebral Column.