Neuroanatomy: dorsal midbrain: 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: dorsal midbrain

Sample item

A 16-year-old boy has headache, vomiting and papilloedema. He cannot look upward, his pupils react poorly to light but briskly to near, and he has convergence-retraction nystagmus. MRI shows a pineal region mass. Which structures are being compressed?

AAbducens nuclei in the pontine tegmentumBSuperior colliculi and pretectal area, with the cerebral aqueductCFloor of the fourth ventricleDCerebral peduncles of the ventral midbrain

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

The answer and the reasoning

B. Superior colliculi and pretectal area, with the cerebral aqueduct

Pineal tumours press on the dorsal midbrain, causing Parinaud syndrome with upgaze palsy, light-near dissociation of the pupils and convergence-retraction nystagmus. The same mass compresses the cerebral aqueduct, causing obstructive hydrocephalus with papilloedema. Germ cell tumours are the commonest pineal masses in the young.

Option by option

A. Abducens nuclei in the pontine tegmentum
Abducens nuclei compression would produce horizontal gaze palsy, not impaired upgaze.
B. Superior colliculi and pretectal area, with the cerebral aqueduct (correct)
Correct. Compression of the superior colliculi, pretectum and aqueduct explains all the findings.
C. Floor of the fourth ventricle
Fourth ventricle floor involvement would affect facial colliculus and vagal nuclei, not upgaze.
D. Cerebral peduncles of the ventral midbrain
Peduncle compression would produce contralateral hemiparesis, not upgaze 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 B, Superior colliculi and pretectal area, with the cerebral aqueduct. Pineal tumours press on the dorsal midbrain, causing Parinaud syndrome with upgaze palsy, light-near dissociation of the pupils and convergence-retraction nystagmus.

Why is "Abducens nuclei in the pontine tegmentum" not the answer?

Abducens nuclei compression would produce horizontal gaze palsy, not impaired upgaze.

Why is "Floor of the fourth ventricle" not the answer?

Fourth ventricle floor involvement would affect facial colliculus and vagal nuclei, not upgaze.

Why is "Cerebral peduncles of the ventral midbrain" not the answer?

Peduncle compression would produce contralateral hemiparesis, not upgaze palsy.

What concept does this question test?

It tests Neuroanatomy: dorsal midbrain in Anatomy. The same mass compresses the cerebral aqueduct, causing obstructive hydrocephalus with papilloedema. Germ cell tumours are the commonest pineal masses in the young.

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 Neuroanatomy: dorsal midbrain?

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.