Neurophysiology and special senses: Horner syndrome: practice question

A Physiology 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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Physiology · Neurophysiology and special senses: Horner syndrome

Sample item

A smoker has miosis, mild ptosis and absence of sweating on the left side of the face, and a left apical lung mass. Which pathway has been interrupted?

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

The answer and the reasoning

A. The sympathetic pathway to the head and eye

The oculosympathetic pathway runs from the hypothalamus through the brainstem and cord to T1, then via the sympathetic chain and the superior cervical ganglion to the eye and face. Interruption, for example by an apical lung tumour, causes miosis, ptosis from paralysis of the superior tarsal muscle, and anhidrosis (Horner syndrome).

Option by option

  • A. The sympathetic pathway to the head and eye (correct)

    Correct. Loss of sympathetic supply causes miosis, ptosis and anhidrosis.

  • B. Motor fibres of the facial nerve

    Facial nerve palsy causes facial weakness and not miosis.

  • C. Parasympathetic fibres in the oculomotor nerve

    Loss of parasympathetic supply would cause a dilated pupil.

  • D. The ophthalmic division of the trigeminal nerve

    Trigeminal damage causes sensory loss, not miosis or anhidrosis.

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 Physiology question

What is the answer to this Physiology question?

The best answer is A, The sympathetic pathway to the head and eye. The oculosympathetic pathway runs from the hypothalamus through the brainstem and cord to T1, then via the sympathetic chain and the superior cervical ganglion to the eye and face.

Why is "Motor fibres of the facial nerve" not the answer?

Facial nerve palsy causes facial weakness and not miosis.

Why is "Parasympathetic fibres in the oculomotor nerve" not the answer?

Loss of parasympathetic supply would cause a dilated pupil.

Why is "The ophthalmic division of the trigeminal nerve" not the answer?

Trigeminal damage causes sensory loss, not miosis or anhidrosis.

What concept does this question test?

It tests Neurophysiology and special senses: Horner syndrome in Physiology. Interruption, for example by an apical lung tumour, causes miosis, ptosis from paralysis of the superior tarsal muscle, and anhidrosis (Horner syndrome).

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 Neurophysiology and special senses: Horner syndrome?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.