Cranial nerve nuclei: 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.

Try it

Anatomy · Cranial nerve nuclei

Sample item

A man has right-sided facial droop after a left hemispheric stroke. His lower face is weak but he can wrinkle both sides of his forehead. What explains the sparing of the forehead?

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

The answer and the reasoning

C. Bilateral corticobulbar input to the upper-face part of the facial nucleus

Neurones of the facial nucleus supplying the forehead muscles receive corticobulbar fibres from both cerebral hemispheres. A unilateral upper motor neurone lesion therefore spares the forehead, while the lower face, with mainly contralateral input, is weak.

Option by option

  • A. The occipitofrontalis muscle is supplied by the oculomotor nerve

    The occipitofrontalis is supplied by the facial nerve, not by the oculomotor nerve.

  • B. The upper face is supplied by the trigeminal nerve

    The trigeminal nerve is sensory to the face and supplies chewing muscles, not forehead wrinkling.

  • C. Bilateral corticobulbar input to the upper-face part of the facial nucleus (correct)

    Correct. Bilateral cortical innervation of the upper-face neurones means one hemisphere's loss is compensated by the other.

  • D. The temporal branch of the facial nerve is separate from the lower branches and was spared

    The stroke lies above the facial nucleus, so nerve branches are not selectively damaged; a lower motor neurone lesion would paralyse the whole half of the face.

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 Anatomy questions

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is C, Bilateral corticobulbar input to the upper-face part of the facial nucleus. Neurones of the facial nucleus supplying the forehead muscles receive corticobulbar fibres from both cerebral hemispheres.

Why is "The occipitofrontalis muscle is supplied by the oculomotor nerve" not the answer?

The occipitofrontalis is supplied by the facial nerve, not by the oculomotor nerve.

Why is "The upper face is supplied by the trigeminal nerve" not the answer?

The trigeminal nerve is sensory to the face and supplies chewing muscles, not forehead wrinkling.

Why is "The temporal branch of the facial nerve is separate from the lower br…" not the answer?

The stroke lies above the facial nucleus, so nerve branches are not selectively damaged; a lower motor neurone lesion would paralyse the whole half of the face.

What concept does this question test?

It tests Cranial nerve nuclei in Anatomy. A unilateral upper motor neurone lesion therefore spares the forehead, while the lower face, with mainly contralateral input, is weak.

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 Cranial nerve nuclei?

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.