A patient with a zygomaticomaxillary complex (ZMC) fracture shows enophthalmos, limitation of upward gaze, and diplopia on upward gaze. This occurs due to:

• A Injury to the oculomotor nerve in the orbit
• B Hematoma compressing the optic nerve
• C Disruption of the zygomaticofacial nerve causing motor palsy
• D Herniation and entrapment of orbital fat and inferior rectus muscle in the orbital floor fracture (blowout component) ✓

Explanation

ZMC fractures often include an orbital floor (blowout) component. When the floor fractures, orbital fat and the inferior rectus muscle may herniate through the fracture into the maxillary sinus, producing entrapment. Entrapment of the inferior rectus causes limitation of upward gaze (the muscle cannot relax normally) and diplopia on upgaze. Enophthalmos results from increased orbital volume due to floor displacement and fat herniation. CN III injury would cause multiple muscle palsies, not isolated upgaze deficit.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.