A 28-year-old man presents with vertical diplopia and enophthalmos 2 weeks after blunt trauma to the right eye. CT orbit shows a blowout fracture of the orbital floor with herniation of orbital contents into the maxillary sinus. The extraocular muscle MOST commonly entrapped in such fractures is:
- A Superior rectus
- B Medial rectus
- C Inferior rectus ✓
- D Inferior oblique
Correct answer: C. Inferior rectus
Explanation
The inferior rectus is the most commonly entrapped muscle in orbital floor blowout fractures because the orbital floor is the weakest wall and lies directly above the maxillary sinus. Entrapment causes vertical diplopia and restriction of upgaze. The inferior oblique can also be involved but less frequently. Superior rectus and medial rectus entrapment are more typical of medial wall fractures.
Reference: Bailey and Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.