Final answer:
The large, air-filled spaces in the facial bones are the paranasal sinuses, particularly located in the frontal, maxilla, sphenoid, and ethmoid bones, which lighten the skull and resonate the voice.
Step-by-step explanation:
The large, air-filled spaces in the bones of the face you are asking about are known as the paranasal sinuses. They are hollow, air-filled spaces located within certain bones of the skull. Notably, these sinuses are found within the frontal, maxilla, sphenoid, and ethmoid bones. The most anterior is the frontal sinus, situated in the frontal bone above the eyebrows. The maxillary sinuses are the largest and are located below the orbits in the right and left maxillary bones. The sphenoid sinus is the most posterior and is situated in the body of the sphenoid bone, while the ethmoid air cells are several small spaces situated in the ethmoid bone.
These sinuses serve to reduce bone mass, thus lightening the skull, and they add resonance to the voice. They are lined with nasal mucosa and are connected to the nasal cavity—significantly, they are all divided at the midline by the nasal septum. The mucosa lining helps warm, humidify incoming air and produces mucus. When these passageways are blocked due to conditions like a cold, they can cause a change in voice and discomfort as they fill with fluid and create pressure.