The skull contains how many sinus cavities?

The skull contains how many sinus cavities?

• A. 3
• B. 4
• C. 5
• D. 6

Answer: (B)

Paranasal sinuses are air-filled spaces within the skull that open into the nasal cavity. There are four main sinus cavities: the maxillary sinuses in the cheek area, the frontal sinuses above the eyes in the forehead region, the ethmoid sinuses within the ethmoid bone (a complex group of small air cells), and the sphenoid sinuses deep in the skull behind the eyes. Even though the ethmoid sinuses are a cluster of multiple small cells, they are counted as one set of sinuses, giving a total of four. These cavities help lighten the skull, contribute to voice resonance, and aid in humidifying and warming inhaled air. Each sinus drains into the nasal cavity through specific openings, which is part of why they’re discussed together as a group.

Paranasal sinuses are air-filled spaces within the skull that open into the nasal cavity. There are four main sinus cavities: the maxillary sinuses in the cheek area, the frontal sinuses above the eyes in the forehead region, the ethmoid sinuses within the ethmoid bone (a complex group of small air cells), and the sphenoid sinuses deep in the skull behind the eyes. Even though the ethmoid sinuses are a cluster of multiple small cells, they are counted as one set of sinuses, giving a total of four. These cavities help lighten the skull, contribute to voice resonance, and aid in humidifying and warming inhaled air. Each sinus drains into the nasal cavity through specific openings, which is part of why they’re discussed together as a group.