Which of the following is a cranial nerve?

• A. Olfactory nerve
• B. Sciatic nerve
• C. Median nerve
• D. Ulnar nerve

Answer: (A)

Cranial nerves originate in the brain and exit the skull, forming part of the twelve nerves that connect directly to brain structures. The olfactory nerve fits this pattern: it is cranial nerve I and carries the sense of smell from the nasal mucosa to the brain, traveling through the cribriform plate to the olfactory bulbs. It is purely sensory. The other nerves listed—one in the leg and two in the arm—are peripheral nerves that arise from spinal nerve plexuses and run in the limbs. They are not cranial nerves. So the olfactory nerve is the cranial nerve.