Question:medium
Damage to the nerve supplying the superior oblique muscle causes diplopia in which direction?
Damage to the nerve supplying the superior oblique muscle causes diplopia in which direction?
Show Hint
The superior oblique (CN IV) depresses the adducted eye, so its palsy gives vertical diplopia worst on downgaze.
Updated On: Jun 24, 2026
- Horizontal and downwards
- Vertical and downwards
- Horizontal and upwards
- Vertical and upwards
Show Solution
The Correct Option is B
Solution and Explanation
Map the anatomy first: the superior oblique is the only muscle run by the trochlear nerve (CN IV). So this question is really asking what a CN IV palsy looks like.
Next, anchor on the muscle's job. The superior oblique pulls the eye downward when the eye is turned in, with secondary intorsion and abduction. Its headline function in clinical testing is depression in adduction, the motion used when walking downstairs or reading. Lose that function and the affected eye cannot be pulled down properly, so it sits a little high relative to the other eye; the two retinal images therefore split top-to-bottom, which the patient perceives as vertical double vision.
Finally, decide where it peaks. A paralysed extraocular muscle gives the largest image separation in its own field of gaze. Since the superior oblique works on downgaze, the diplopia becomes worst when the patient looks down, which is exactly why these patients tilt the head and struggle on stairs. Combining direction and gaze position gives vertical diplopia, worst downwards.
\[\boxed{\text{Vertical and downwards}}\]
Next, anchor on the muscle's job. The superior oblique pulls the eye downward when the eye is turned in, with secondary intorsion and abduction. Its headline function in clinical testing is depression in adduction, the motion used when walking downstairs or reading. Lose that function and the affected eye cannot be pulled down properly, so it sits a little high relative to the other eye; the two retinal images therefore split top-to-bottom, which the patient perceives as vertical double vision.
Finally, decide where it peaks. A paralysed extraocular muscle gives the largest image separation in its own field of gaze. Since the superior oblique works on downgaze, the diplopia becomes worst when the patient looks down, which is exactly why these patients tilt the head and struggle on stairs. Combining direction and gaze position gives vertical diplopia, worst downwards.
\[\boxed{\text{Vertical and downwards}}\]
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