What connects the sinus cavities to the nasal passage?

The sinus cavities are connected to the nasal passage through structures known as ostia. Ostia are small openings or ducts that allow drainage from the sinuses into the nasal cavity, playing a crucial role in ventilation and drainage. This connection is essential for the health of the sinuses, as it helps to prevent blockage and allows mucus to flow freely, maintaining a balance within the sinus and nasal systems.

Turbinates, on the other hand, are bony structures inside the nasal cavity that help to humidify and filter the air we breathe, but they do not directly connect the sinuses to the nasal passage. Fissures are narrow openings or gaps between the bones of the skull, which are not involved in the drainage of the sinus cavities. Cartilage makes up structures such as the nose itself but does not facilitate the connection between the sinuses and the nasal passage. Thus, ostia serve a vital and specific role in linking the sinuses to the nasal passages, which is why this choice is the correct answer.