Neuroanatomy: mesencephalic nucleus of the trigeminal nerve: 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: mesencephalic nucleus of the trigeminal nerve

Sample item

Which trigeminal nucleus contains the cell bodies of primary afferent neurons carrying jaw proprioception, and is unusual because these cell bodies lie inside the central nervous system?

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

The answer and the reasoning

A. Mesencephalic nucleus

The mesencephalic nucleus holds pseudounipolar proprioceptive neurons from the masticatory muscles and periodontal ligaments, which is an exception to the rule that primary afferent cell bodies lie in ganglia. The chief sensory nucleus relays discriminative touch and the spinal nucleus relays pain and temperature. The motor nucleus supplies the muscles of mastication.

Option by option

  • A. Mesencephalic nucleus (correct)

    Correct. Its neurons are primary afferents whose cell bodies lie in the brainstem.

  • B. Chief sensory nucleus

    The chief sensory nucleus receives afferents whose cell bodies lie in the trigeminal ganglion.

  • C. Motor nucleus

    The motor nucleus contains efferent neurons, not afferent cell bodies.

  • D. Spinal nucleus

    The spinal nucleus relays ganglion-derived pain and temperature fibres.

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 Anatomy question

What is the answer to this Anatomy question?

The best answer is A, Mesencephalic nucleus. The mesencephalic nucleus holds pseudounipolar proprioceptive neurons from the masticatory muscles and periodontal ligaments, which is an exception to the rule that primary afferent cell bodies lie in ganglia.

Why is "Chief sensory nucleus" not the answer?

The chief sensory nucleus receives afferents whose cell bodies lie in the trigeminal ganglion.

Why is "Motor nucleus" not the answer?

The motor nucleus contains efferent neurons, not afferent cell bodies.

Why is "Spinal nucleus" not the answer?

The spinal nucleus relays ganglion-derived pain and temperature fibres.

What concept does this question test?

It tests Neuroanatomy: mesencephalic nucleus of the trigeminal nerve in Anatomy. The chief sensory nucleus relays discriminative touch and the spinal nucleus relays pain and temperature. The motor nucleus supplies the muscles of mastication.

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: mesencephalic nucleus of the trigeminal nerve?

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.