Nerves which convey special sensory information related to smell?

Appeared in: AIIMS Raipur NO - 2019 (Shift-2)

Explanation

The Olfactory nerve, also known as Cranial Nerve I (CN I), is a sensory nerve dedicated solely to the sense of smell (olfaction).
It originates in the olfactory epithelium in the upper part of the nasal cavity and transmits signals to the olfactory bulb in the brain.
This nerve is responsible for detecting and interpreting various odors from the environment.

Option A: The Oculomotor nerve (CN III) is primarily a motor nerve that controls most of the eye's movements, the muscle that raises the eyelid, and pupil constriction. It has no sensory function related to smell.
Option B: The Optic nerve (CN II) is a sensory nerve that transmits visual information from the retina to the brain. It is responsible for the sense of sight, not smell.
Option D: The Trochlear nerve (CN IV) is a motor nerve that controls a single muscle of the eye, the superior oblique muscle, which is involved in downward and inward eye movement. It has no role in the sense of smell.

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.
Nurses may be involved in assessing cranial nerve function, including the sense of smell. A simple bedside test involves asking the patient to identify common, non-irritating scents (like coffee or soap) with each nostril closed.
Loss of smell (anosmia) can be an early sign of neurodegenerative diseases like Parkinson's or Alzheimer's, or it can result from head trauma, sinus infections, or viral illnesses (e.g., COVID-19).
What if? If a patient reports a sudden loss of smell after a head injury, the priority is to assess for other neurological deficits and report immediately, as this could indicate a fracture of the cribriform plate and a potential cerebrospinal fluid (CSF) leak.

How to Approach the Question

First, identify the key function in the question: 'special sensory information related to smell'.
Recall the 12 cranial nerves and their primary functions. This is a factual recall question.
Associate the term 'olfaction' with the sense of smell.
Systematically evaluate each option: 'Oculomotor' and 'Trochlear' are primarily for eye movement. 'Optic' is for vision. 'Olfactory' directly relates to smell.
Select the nerve whose name and function match the question's requirement.

Concept Tested & Keywords

QLIhRSYu6Nx2N4Q6eE7O1-

E6 Anatomy Applied Ashalatha 4e p. 425-427

E6 Medicine Macleod Clinical Examination 15e p. 150-152

E6 Anatomy Grays 43e Vol 1 Part 3 p. 34-36

Practise the full AIIMS Raipur NO - 2019 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.