Psychiatric-Mental Health Nurse Practitioner Exam

Which of the following cranial nerves is responsible for smell?

1. Optic nerve

2. Facial nerve

3. Vagus nerve

4. Olfactory nerve

The correct answer is: Olfactory nerve

The olfactory nerve is responsible for the sense of smell, making it the correct answer. This nerve, cranial nerve I, is specifically dedicated to transmitting sensory information from the nasal cavity to the brain, allowing individuals to perceive odors. Unlike other cranial nerves that have multiple functions, the olfactory nerve primarily handles olfaction (the sense of smell) through its olfactory receptor neurons located in the mucosa of the nasal cavity. In contrast, the optic nerve is involved in vision, the facial nerve plays a significant role in facial expressions and taste sensation but not smell, and the vagus nerve regulates various autonomic functions and sensation in the throat and abdomen, but it does not have a role in the sense of smell. Thus, the olfactory nerve's singular focus on olfactory input clearly distinguishes it as the cranial nerve that is responsible for the sense of smell.