Neuroanatomy: Argyll Robertson pupil: practice question

A Anatomy 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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Anatomy · Neuroanatomy: Argyll Robertson pupil

Sample item

A man with long-standing untreated syphilis has small, irregular pupils that constrict on near focus but not to light. Which site is damaged?

APretectal nuclei in the dorsal midbrainBCiliary ganglion in the orbitCOptic tract just before the lateral geniculate bodyDEdinger-Westphal nucleus supplying the ciliary ganglion

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

The answer and the reasoning

A. Pretectal nuclei in the dorsal midbrain

In the Argyll Robertson pupil the light reflex pathway is interrupted at the pretectal area while the near-response pathway, which bypasses it, is intact: light-near dissociation. Damage to the ciliary ganglion produces a tonic (Adie) pupil instead.

Option by option

A. Pretectal nuclei in the dorsal midbrain (correct)
Correct. Pretectal damage abolishes the light reflex while accommodation-convergence is spared.
B. Ciliary ganglion in the orbit
Ciliary ganglion damage gives a dilated tonic pupil that reacts slowly to both stimuli.
C. Optic tract just before the lateral geniculate body
An optic tract lesion produces a hemianopia and a relative afferent defect, not light-near dissociation.
D. Edinger-Westphal nucleus supplying the ciliary ganglion
The Edinger-Westphal nucleus serves both light and near responses, so both would fail.

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 Anatomy question

What is the answer to this Anatomy question?

The best answer is A, Pretectal nuclei in the dorsal midbrain. In the Argyll Robertson pupil the light reflex pathway is interrupted at the pretectal area while the near-response pathway, which bypasses it, is intact: light-near dissociation.

Why is "Ciliary ganglion in the orbit" not the answer?

Ciliary ganglion damage gives a dilated tonic pupil that reacts slowly to both stimuli.

Why is "Optic tract just before the lateral geniculate body" not the answer?

An optic tract lesion produces a hemianopia and a relative afferent defect, not light-near dissociation.

Why is "Edinger-Westphal nucleus supplying the ciliary ganglion" not the answer?

The Edinger-Westphal nucleus serves both light and near responses, so both would fail.

What concept does this question test?

It tests Neuroanatomy: Argyll Robertson pupil in Anatomy. Damage to the ciliary ganglion produces a tonic (Adie) pupil instead.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Neuroanatomy: Argyll Robertson pupil?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy 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.