Neuroanatomy: internal capsule: 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: internal capsule

Sample item

A lacunar infarct in the posterior limb of the internal capsule is most likely to produce which deficit?

AIpsilateral facial pain lossBIsolated homonymous hemianopiaCContralateral pure motor weaknessDBilateral lower-motor-neuron paralysis

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

The answer and the reasoning

C. Contralateral pure motor weakness

The posterior limb contains densely packed corticospinal fibres; a small infarct can cause contralateral pure motor hemiparesis. Sensory fibres are nearby but the classic syndrome is motor.

Option by option

A. Ipsilateral facial pain loss
Facial pain pathways are not localised to the posterior limb in this way.
B. Isolated homonymous hemianopia
Optic radiations, not the posterior limb, produce visual-field loss.
C. Contralateral pure motor weakness (correct)
Correct. Corticospinal tract disruption causes contralateral motor weakness.
D. Bilateral lower-motor-neuron paralysis
A unilateral capsular lesion does not produce bilateral LMN paralysis.

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 C, Contralateral pure motor weakness. The posterior limb contains densely packed corticospinal fibres; a small infarct can cause contralateral pure motor hemiparesis.

Why is "Ipsilateral facial pain loss" not the answer?

Facial pain pathways are not localised to the posterior limb in this way.

Why is "Isolated homonymous hemianopia" not the answer?

Optic radiations, not the posterior limb, produce visual-field loss.

Why is "Bilateral lower-motor-neuron paralysis" not the answer?

A unilateral capsular lesion does not produce bilateral LMN paralysis.

What concept does this question test?

It tests Neuroanatomy: internal capsule in Anatomy. Sensory fibres are nearby but the classic syndrome is motor.

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 Neuroanatomy: internal capsule?

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.