Anatomy: lid muscles and innervation: practice question

A Ophthalmology 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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Ophthalmology · Anatomy: lid muscles and innervation

Sample item

A patient with Horner syndrome shows mild ptosis. Which lid muscle is paralysed and what is its supply?

AFrontalis, facial nerveBLevator palpebrae superioris, oculomotor nerveCOrbicularis oculi, facial nerveDMuller muscle, sympathetic supply

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

The answer and the reasoning

D. Muller muscle, sympathetic supply

Muller muscle contributes about 2 mm of lid elevation and is supplied by sympathetic fibres. Its paralysis in Horner syndrome gives mild ptosis. Levator palpebrae is supplied by the oculomotor nerve and produces most lid elevation.

Option by option

A. Frontalis, facial nerve
Frontalis is an accessory elevator of the brow.
B. Levator palpebrae superioris, oculomotor nerve
Levator is spared in Horner syndrome and would cause severe ptosis if paralysed.
C. Orbicularis oculi, facial nerve
Orbicularis closes the lid and its paralysis causes lagophthalmos.
D. Muller muscle, sympathetic supply (correct)
Correct. Sympathetic denervation of Muller muscle causes mild ptosis.

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 Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is D, Muller muscle, sympathetic supply. Muller muscle contributes about 2 mm of lid elevation and is supplied by sympathetic fibres.

Why is "Frontalis, facial nerve" not the answer?

Frontalis is an accessory elevator of the brow.

Why is "Levator palpebrae superioris, oculomotor nerve" not the answer?

Levator is spared in Horner syndrome and would cause severe ptosis if paralysed.

Why is "Orbicularis oculi, facial nerve" not the answer?

Orbicularis closes the lid and its paralysis causes lagophthalmos.

What concept does this question test?

It tests Anatomy: lid muscles and innervation in Ophthalmology. Its paralysis in Horner syndrome gives mild ptosis. Levator palpebrae is supplied by the oculomotor nerve and produces most lid elevation.

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 Anatomy: lid muscles and innervation?

Group the red eye by what to examine and what the pupil does. Then use the flashcards and the other Ophthalmology 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.