The paranasal sinus located within the maxilla is the?

• A. Maxilla
• B. Mandible
• C. Frontal bone
• D. Ethmoid bone

Answer: (A)

Paranasal sinuses are air-filled cavities that lie within specific skull bones and open into the nasal cavity. Each sinus is named for the bone that houses it. The sinus located within the maxilla is the maxillary sinus. It sits in the body of the maxilla, just above the upper teeth, and drains into the middle nasal meatus through an opening on its medial wall. This is why upper dental infections can sometimes involve the sinus.

The other sinuses are found in their respective bones: the frontal sinus in the frontal bone, the ethmoid air cells in the ethmoid bone, and the sphenoid sinus in the sphenoid bone. The mandible does not contain a paranasal sinus.