Which cranial nerve is primarily involved in the sense of smell?

The olfactory nerve, also known as cranial nerve I, is primarily responsible for the sense of smell. This nerve contains sensory fibers that transmit information related to odors from the olfactory epithelium in the nasal cavity directly to the olfactory bulb in the brain. This process begins when odorant molecules bind to olfactory receptors, leading to neuronal activation that sends signals to the brain, enabling the perception of smells.

Unlike the olfactory nerve, the trigeminal nerve is involved in sensations of touch, pain, and temperature for the face, as well as controlling muscles for biting and chewing. The facial nerve plays a role in taste sensations from the anterior two-thirds of the tongue and controlling facial expressions, while the vestibulocochlear nerve is involved in hearing and balance, transporting sensory information from the inner ear. Therefore, the distinct function of the olfactory nerve positions it as the key player in the sense of smell among the listed cranial nerves.