The sinuses are hollow cavities within the facial bones. Sinuses are not fully developed until after age 12. When people speak of sinus infections, they are most frequently referring to the maxillary and ethmoid sinuses.
Review Date: 5/30/2021
Reviewed By: Denis Hadjiliadis, MD, MHS, Paul F. Harron, Jr. Associate Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.