Neurophysiology: thalamic relay: 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 · Neurophysiology: thalamic relay

Sample item

A lacunar infarct causes loss of all sensory modalities over the left side of the trunk and limbs, but the left face is spared. Which structure is affected?

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

The answer and the reasoning

B. Right ventral posterolateral nucleus of the thalamus

The ventral posterolateral nucleus relays spinothalamic and medial lemniscal input from the contralateral body to the somatosensory cortex. The ventral posteromedial nucleus relays the face. A lesion of the right ventral posterolateral nucleus therefore causes left hemibody sensory loss.

Option by option

  • A. Right medial geniculate body

    The medial geniculate body relays hearing.

  • B. Right ventral posterolateral nucleus of the thalamus (correct)

    Correct. This nucleus relays sensation from the contralateral trunk and limbs.

  • C. Right ventral posteromedial nucleus of the thalamus

    The posteromedial nucleus relays face sensation, which is preserved here.

  • D. Right lateral geniculate body

    The lateral geniculate body relays 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 B, Right ventral posterolateral nucleus of the thalamus. The ventral posterolateral nucleus relays spinothalamic and medial lemniscal input from the contralateral body to the somatosensory cortex.

Why is "Right medial geniculate body" not the answer?

The medial geniculate body relays hearing.

Why is "Right ventral posteromedial nucleus of the thalamus" not the answer?

The posteromedial nucleus relays face sensation, which is preserved here.

Why is "Right lateral geniculate body" not the answer?

The lateral geniculate body relays vision.

What concept does this question test?

It tests Neurophysiology: thalamic relay in Physiology. The ventral posteromedial nucleus relays the face. A lesion of the right ventral posterolateral nucleus therefore causes left hemibody sensory loss.

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: thalamic relay?

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.