Special senses: macular sparing: 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: macular sparing

Sample item

A man has an acute right homonymous hemianopia after an occipital stroke, but central vision is preserved. Which explanation is most accurate?

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

The answer and the reasoning

D. The occipital pole receives dual supply from the middle cerebral artery as well as the posterior cerebral artery

The posterior cerebral artery supplies most of the calcarine cortex, but the occipital pole, which represents the macula, may also receive collateral flow from the middle cerebral artery. After posterior cerebral occlusion, macular representation can survive, giving hemianopia with macular sparing. The macula has a large cortical magnification.

Option by option

  • A. Macular vision is carried through the superior colliculus

    The superior colliculus does not carry conscious central vision.

  • B. The macula is represented in the lateral geniculate body only

    The macula is represented in the cortex and not solely in the geniculate body.

  • C. Macular fibres cross at the chiasm and are therefore spared

    Macular fibres cross in the chiasm like others and do not avoid the lesion in this way.

  • D. The occipital pole receives dual supply from the middle cerebral artery as well as the posterior cerebral artery (correct)

    Correct. Dual arterial supply protects the occipital pole representing central 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.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is D, The occipital pole receives dual supply from the middle cerebral artery as well as the posterior cerebral artery. The posterior cerebral artery supplies most of the calcarine cortex, but the occipital pole, which represents the macula, may also receive collateral flow from the middle cerebral artery.

Why is "Macular vision is carried through the superior colliculus" not the answer?

The superior colliculus does not carry conscious central vision.

Why is "The macula is represented in the lateral geniculate body only" not the answer?

The macula is represented in the cortex and not solely in the geniculate body.

Why is "Macular fibres cross at the chiasm and are therefore spared" not the answer?

Macular fibres cross in the chiasm like others and do not avoid the lesion in this way.

What concept does this question test?

It tests Special senses: macular sparing in Physiology. After posterior cerebral occlusion, macular representation can survive, giving hemianopia with macular sparing. The macula has a large cortical magnification.

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 Special senses: macular sparing?

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.