Neuroanatomy: Weber syndrome: 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: Weber syndrome

Sample item

A 65-year-old man has drooping of the right upper eyelid with the right eye down and out and the pupil dilated, plus weakness of the left arm, leg and lower face. Where is the lesion?

ARight cerebral peduncle in the midbrainBLeft posterior limb of the internal capsuleCRight basal ponsDRight lateral medulla

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

The answer and the reasoning

A. Right cerebral peduncle in the midbrain

Weber syndrome is an ipsilateral oculomotor palsy with contralateral hemiparesis due to a lesion in the ventral midbrain involving the cerebral peduncle (crus cerebri), where the oculomotor fascicles emerge and corticospinal and corticobulbar fibres descend. It results from occlusion of paramedian branches of the posterior cerebral artery or the basilar bifurcation.

Option by option

A. Right cerebral peduncle in the midbrain (correct)
A lesion of the cerebral peduncle affects fascicles of CN III and the descending corticospinal tract, and gives the combination.
B. Left posterior limb of the internal capsule
An internal capsule lesion would cause contralateral hemiparesis without an ipsilateral oculomotor palsy.
C. Right basal pons
A basal pontine lesion would affect the abducens or facial nerve with contralateral hemiparesis.
D. Right lateral medulla
The lateral medullary lesion produces Wallenberg syndrome without oculomotor palsy.

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, Right cerebral peduncle in the midbrain. Weber syndrome is an ipsilateral oculomotor palsy with contralateral hemiparesis due to a lesion in the ventral midbrain involving the cerebral peduncle (crus cerebri), where the oculomotor fascicles emerge and corticospinal and corticobulbar fibres descend.

Why is "Left posterior limb of the internal capsule" not the answer?

An internal capsule lesion would cause contralateral hemiparesis without an ipsilateral oculomotor palsy.

Why is "Right basal pons" not the answer?

A basal pontine lesion would affect the abducens or facial nerve with contralateral hemiparesis.

Why is "Right lateral medulla" not the answer?

The lateral medullary lesion produces Wallenberg syndrome without oculomotor palsy.

What concept does this question test?

It tests Neuroanatomy: Weber syndrome in Anatomy. It results from occlusion of paramedian branches of the posterior cerebral artery or the basilar bifurcation.

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: Weber syndrome?

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.