Onodi cells

• Onodi cells are the posterior most cells of the ethmoid sinus
• It is located superolateral to the sphenoid sinus and is in close relation to the optic nerve
• It may sometimes surround the optic nerve

Clinical importance:

• Attempt to remove the onodi cells during sinus surgery may cause injury to the optic nerve
• The onodi cells are a potential cause for incomplete sphenoidectomy
  • The anatomical landmarks of the sphenoid sinus correlate with that of onodi cells
  • Hence, the surgeon may mistakenly believe that the sphenoid sinus has been reached

Reference:
Otorhinolaryngology, Head and Neck Surgery By Matti Anniko, Manuel Bernal-Sprekelsen, Patrick Bradley