A 28-year-old man complains of double vision when walking down stairs and while reading. On examination, the affected eye is elevated and extorted at rest, and the diplopia worsens when the head is tilted toward the opposite shoulder. Which muscle is weak?

• A Superior rectus
• B Superior oblique ✓
• C Inferior oblique
• D Levator palpebrae superioris

Explanation

The superior oblique intorts, abducts and depresses the adducted eye. Its weakness produces vertical diplopia worst on looking down and inward, classically noticed on descending stairs, and compensatory head tilt away from the affected side. Inferior oblique weakness would cause depression problems in adduction rather than this pattern, and superior rectus weakness elevates rather than depresses the visual axis deficit.

Reference: Gray's Anatomy for Students, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.