The sinuses are hollow cavities within the facial bones. Sinuses are not fully developed until after age twelve. When people speak of sinus infections, they are most frequently referring to the maxillary and ethmoid sinuses.
Reviewed By: Sumana Jothi MD, Specialist in Laryngology, Clinical Instructor UCSF Otolaryngology, NCHCS VA, SFVA, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.