Special senses: olfaction: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Special senses: olfaction

Sample item

After a road traffic accident with fracture of the cribriform plate, a young man cannot smell coffee but can sense the pungency of ammonia. Which structures were most likely torn?

AUnmyelinated axons of olfactory receptor neurons forming the fila olfactoriaBFibres of the chorda tympaniCFibres of the trigeminal nerveDAxons of mitral cells in the olfactory tract

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Unmyelinated axons of olfactory receptor neurons forming the fila olfactoria

Olfactory receptor neurons are bipolar cells in the olfactory epithelium whose unmyelinated axons pass through the cribriform plate to synapse on mitral cells in the olfactory bulb. Shearing at this site causes anosmia. Ammonia is detected by trigeminal nociceptors, which are preserved.

Option by option

A. Unmyelinated axons of olfactory receptor neurons forming the fila olfactoria (correct)
Correct. These axons cross the cribriform plate and are vulnerable to shearing.
B. Fibres of the chorda tympani
The chorda tympani carries taste from the anterior tongue and does not pass through the cribriform plate.
C. Fibres of the trigeminal nerve
Trigeminal fibres detect irritants such as ammonia, which this patient senses.
D. Axons of mitral cells in the olfactory tract
Mitral cell axons run in the olfactory tract above the cribriform plate and are not damaged by its fracture.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is A, Unmyelinated axons of olfactory receptor neurons forming the fila olfactoria. Olfactory receptor neurons are bipolar cells in the olfactory epithelium whose unmyelinated axons pass through the cribriform plate to synapse on mitral cells in the olfactory bulb.

Why is "Fibres of the chorda tympani" not the answer?

The chorda tympani carries taste from the anterior tongue and does not pass through the cribriform plate.

Why is "Fibres of the trigeminal nerve" not the answer?

Trigeminal fibres detect irritants such as ammonia, which this patient senses.

Why is "Axons of mitral cells in the olfactory tract" not the answer?

Mitral cell axons run in the olfactory tract above the cribriform plate and are not damaged by its fracture.

What concept does this question test?

It tests Special senses: olfaction in Physiology. Shearing at this site causes anosmia. Ammonia is detected by trigeminal nociceptors, which are preserved.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Special senses: olfaction?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.