Neurophysiology and special senses: optic chiasm lesion: 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.

Try it

Physiology · Neurophysiology and special senses: optic chiasm lesion

Sample item

A 35-year-old woman with galactorrhoea has bitemporal hemianopia. Which fibres are interrupted?

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

The answer and the reasoning

A. Crossing fibres from the nasal retina at the optic chiasm

Nasal retinal fibres from each eye carry the temporal visual fields and cross in the chiasm. A pituitary tumour compressing the chiasm interrupts these crossing fibres and causes bitemporal hemianopia.

Option by option

  • A. Crossing fibres from the nasal retina at the optic chiasm (correct)

    Correct. Crossing nasal retinal fibres carry the temporal fields.

  • B. The optic nerve of one eye

    Damage to one optic nerve causes loss of vision in that eye only.

  • C. Uncrossed fibres from the temporal retina of both eyes

    Uncrossed temporal fibre damage would cause binasal defects.

  • D. Optic radiations in the temporal lobe

    Temporal radiation damage causes a contralateral upper quadrantanopia.

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.

More Physiology questions

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is A, Crossing fibres from the nasal retina at the optic chiasm. Nasal retinal fibres from each eye carry the temporal visual fields and cross in the chiasm.

Why is "The optic nerve of one eye" not the answer?

Damage to one optic nerve causes loss of vision in that eye only.

Why is "Uncrossed fibres from the temporal retina of both eyes" not the answer?

Uncrossed temporal fibre damage would cause binasal defects.

Why is "Optic radiations in the temporal lobe" not the answer?

Temporal radiation damage causes a contralateral upper quadrantanopia.

What concept does this question test?

It tests Neurophysiology and special senses: optic chiasm lesion in Physiology. A pituitary tumour compressing the chiasm interrupts these crossing fibres and causes bitemporal hemianopia.

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 Neurophysiology and special senses: optic chiasm lesion?

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.