[5] Postganglionic parasympathetic fibers of the facial nerve that synapsed at the pterygopalatine ganglion control mucus secretion.

[1] However, patients with isolated sphenoid sinusitis may complain of occipital or vertex headache, retro-orbital pain, otalgia, drowsiness, or meningitis-like symptoms.

[citation needed] If the tumor spreads laterally, the cavernous sinus and all its constituent nerves may be in danger.

Onodi cells typically extend back to lie superolateral to the sphenoid sinus and thus near the optic nerve and internal carotid artery.

[9] Failure to recognize an Onodi cell on CT scan before surgery may put these structures at risk.

[citation needed] This article incorporates text in the public domain from page 998 of the 20th edition of Gray's Anatomy (1918)