Which statement about paranasal sinuses is true?

Which statement about paranasal sinuses is true?

• A. They Are Air-Filled Pockets Within the Cranium
• B. They Are Not Connected to the Nasal Cavity
• C. They Are Lined With Non-Ciliated Mucous Membrane
• D. They Decrease Skull Weight

Answer: (A)

Paranasal sinuses are air-filled cavities within the bones that surround the nasal cavity. This air-filled character is the defining feature: they are pockets inside the skull bones that open into the nasal passages. They are not isolated from the nasal cavity, since they drain into it, and they are lined with a ciliated mucous membrane (not non-ciliated), which explains why the other statements aren’t correct. While a secondary effect of having air-filled spaces is a lightening of the skull, the most direct true statement emphasized here is their air-filled nature within the skull.

Paranasal sinuses are air-filled cavities within the bones that surround the nasal cavity. This air-filled character is the defining feature: they are pockets inside the skull bones that open into the nasal passages. They are not isolated from the nasal cavity, since they drain into it, and they are lined with a ciliated mucous membrane (not non-ciliated), which explains why the other statements aren’t correct. While a secondary effect of having air-filled spaces is a lightening of the skull, the most direct true statement emphasized here is their air-filled nature within the skull.