Which cranial nerve is responsible for the sense of smell?

RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Applied Anatomy

Easy

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Explanation

The Olfactory nerve is the first cranial nerve (CN I).
It is a special sensory nerve that is solely responsible for transmitting information related to the sense of smell (olfaction) from the nasal cavity to the brain.
Its nerve fibers originate in the olfactory epithelium of the nasal cavity and pass through the cribriform plate to synapse in the olfactory bulb.

Option A: The Optic nerve (CN II) is responsible for the sense of sight (vision), not smell.
Option C: The Vestibulocochlear nerve (CN VIII) is responsible for hearing and balance (equilibrium), not smell.
Option D: The Oculomotor nerve (CN III) is a motor nerve that controls most of the movements of the eyeball and eyelid, as well as pupil constriction. It has no sensory function for smell.

Visual 1: Diagram - An illustration showing the 12 pairs of cranial nerves originating from the brain, with each nerve clearly labeled with its name and Roman numeral. This helps in memorizing their sequence and location.
Visual 2: Flowchart - A chart depicting the pathway of the olfactory nerve from the nasal epithelium through the cribriform plate to the olfactory bulb and cortex, illustrating how smell signals are processed.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Functions of Cranial Nerves as background academic context rather than a clinical decision trigger.
A nurse may assess the function of the olfactory nerve by asking the patient to identify common, non-irritating scents (like coffee or vanilla) with each nostril closed. This is a standard part of a neurological examination.
Loss of smell, known as anosmia, can be a significant clinical finding. It can result from common colds, head trauma (especially fractures of the anterior cranial fossa), tumors, or neurodegenerative diseases like Parkinson's or Alzheimer's disease.
What if? If a patient reports a sudden loss of smell after a motor vehicle accident, the nurse should suspect a possible basal skull fracture affecting the cribriform plate and immediately report this to the physician, as it could also indicate a cerebrospinal fluid (CSF) leak.

How to Approach the Question

This is a factual recall question that tests your knowledge of neuroanatomy.
First, identify the key terms in the question: "cranial nerve" and "sense of smell".
Mentally review the 12 cranial nerves and their primary functions.
Associate the "sense of smell" with its corresponding nerve, which is the Olfactory nerve (CN I).
Evaluate the given options. 'Optic' relates to vision, 'Vestibulocochlear' to hearing/balance, and 'Oculomotor' to eye movement.
Select 'Olfactory' as it is the only nerve listed that is dedicated to the sense of smell.

Concept Tested & Keywords

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