Ans: Cranial and spinal nerves are two main components of the human body. From the abbreviations, we can understand that cranial nerve is related to the brain and the spinal nerve is related to the spinal cord of human physiology. The cranial nerves emerge directly from the brainstem while the spinal nerves directly emerge from the spinal cord segments. These nerves differ from each other in their structures and functions but both are necessary in carrying out the functions of nervous system.