During FESS, uncinectomy is the critical first step. The uncinate process is a bony projection of the ethmoid bone. Its superior attachment determines the drainage pathway of the frontal sinus. If the uncinate attaches to the lamina papyracea, the frontal sinus drains:

• A Into the ethmoidal infundibulum, medial to the uncinate
• B Directly into the middle meatus, lateral to the uncinate (frontal recess drains between uncinate and middle turbinate) ✓
• C Through the frontal recess into the infundibulum, posterior to the uncinate
• D Through the agger nasi cells directly into the superior meatus

Explanation

The superior attachment of the uncinate process determines the frontal sinus drainage pathway (critical concept): if it attaches LATERALLY to the lamina papyracea, the frontal recess drains MEDIALLY to the uncinate, directly into the middle meatus (NOT through the infundibulum). If it attaches MEDIALLY (to the middle turbinate or skull base), the frontal recess drains into the infundibulum (and thus communicates with the maxillary sinus ostium). Understanding this anatomical variation is essential to avoid inadvertent damage to the frontal recess during uncinectomy in FESS.

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

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Written and medically reviewed by the StethoPrep medical team.