A meatus is a passage or opening in the body. In the context of the respiratory system, it often refers to the nasal passages that air flows through.
Nasal cavity: The space behind the nose where air passes and gets warmed, humidified, and filtered.
Sinuses: Air-filled spaces in the skull that help humidify and filter inhaled air.
Turbinates: Long, narrow shelves of bone that protrude into the nasal cavity and help to warm and moisten air as it flows through