The Onodi cell (sphenoethmoid cell) is surgically relevant because it:

• A Is the posteriormost ethmoid cell that extends superolateral to the sphenoid and may contain the optic nerve ✓
• B Lies anterior to the frontal recess and can be confused with the frontal sinus
• C Is the largest anterior ethmoid cell lying above the agger nasi
• D Communicates directly with the maxillary sinus and carries the infraorbital nerve

Explanation

The Onodi cell (also called sphenoethmoidal cell) is the most posterior ethmoid cell which pneumatises posterolaterally to the sphenoid sinus. It is critically important because the optic nerve and internal carotid artery may be dehiscent in its wall, putting them at risk during sphenoid or posterior ethmoid surgery. Failure to recognise an Onodi cell may result in the surgeon mistaking it for the sphenoid sinus, endangering the optic nerve.

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.