Neuroanatomy: 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

Sample item

A man with a posterior cerebral artery infarct has a right homonymous hemianopia, but the central vision of the right fields is preserved. What explains this macular sparing?

ADual blood supply of the occipital pole from the PCA and the MCABCollateral supply from the anterior cerebral arteryCCrossing of macular fibres in the optic chiasmaDSeparate pathway through the pretectal nucleus

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

The answer and the reasoning

A. Dual blood supply of the occipital pole from the PCA and the MCA

The occipital pole, where the macula is represented, receives anastomotic supply from the middle cerebral artery in addition to the posterior cerebral artery, so central vision may be spared in PCA infarction.

Option by option

A. Dual blood supply of the occipital pole from the PCA and the MCA (correct)
Correct. Overlapping PCA and MCA supply protects the macular representation.
B. Collateral supply from the anterior cerebral artery
The anterior cerebral artery does not supply the occipital pole.
C. Crossing of macular fibres in the optic chiasma
Macular fibres cross at the chiasma like others and do not explain sparing.
D. Separate pathway through the pretectal nucleus
The pretectal nucleus is part of the pupillary light reflex and does not carry vision.

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, Dual blood supply of the occipital pole from the PCA and the MCA. The occipital pole, where the macula is represented, receives anastomotic supply from the middle cerebral artery in addition to the posterior cerebral artery, so central vision may be spared in PCA infarction.

Why is "Collateral supply from the anterior cerebral artery" not the answer?

The anterior cerebral artery does not supply the occipital pole.

Why is "Crossing of macular fibres in the optic chiasma" not the answer?

Macular fibres cross at the chiasma like others and do not explain sparing.

Why is "Separate pathway through the pretectal nucleus" not the answer?

The pretectal nucleus is part of the pupillary light reflex and does not carry vision.

What concept does this question test?

It tests Neuroanatomy in Anatomy. The correct option holds because: Correct. Overlapping PCA and MCA supply protects the macular representation.

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?

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.