Wiktionary
maxillary sinus
n. (context anatomy English) A paranasal sinus found in the body of the maxilla.
WordNet
maxillary sinus
n. one of a pair of sinuses forming a cavity in the maxilla
Wikipedia
Maxillary sinus
The pyramid-shaped maxillary sinus (or antrum of Highmore) is the largest of the paranasal sinuses, and drains into the middle meatus of the nose.
Usage examples of "maxillary sinus".
As I skimmed the first page of the report, trying to decipher the medical jargon, I was not surprised to find that a transmitting beacon had been implanted in Kali's maxillary sinus cavity which was capable of sending long-range signals, presumably to HelixCorp.