What is the composition of the anterior and posterior ethmoid sinuses?

Updated: Mar 01, 2018
  • Author: Itzhak Brook, MD, MSc; Chief Editor: Michael Stuart Bronze, MD  more...
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Anterior and posterior ethmoid sinuses are composed of multiple air cells separated by thin bony partitions. Each cell is drained by an independent ostium that measures only 1-2 mm in diameter. These small openings are readily clogged by secretions or are occluded by swelling of the nasal mucosa. The sphenoid sinuses sit immediately anterior to the pituitary fossa and just behind the posterior ethmoid.

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