Definition
An air-filled cavity in the bone of the upper jaw, located beneath each cheek and above the upper teeth, that connects to the nasal passage through a small opening. As one of the paranasal sinuses, it is subject to pressure changes during climbs and descents and can cause facial pain if congestion blocks the opening.
Plain English
A hollow space inside the bone of your cheek, just above your upper teeth, that connects to your nose through a tiny opening. If that opening gets blocked by a cold or congestion, the trapped air can cause pain when cabin pressure changes.
Context Anchor
Seen in discussions of sinus trouble during altitude changes, especially when flying with a cold, allergy, or blocked nose.
Derivation
From the Latin maxilla, meaning 'upper jawbone,' and sinus, meaning 'a hollow' or 'curve.' So 'maxillary sinus' literally means 'the hollow in the upper jaw' -- which is exactly where it sits.
Why Pilots Care
A blocked maxillary sinus prevents pressure equalization, producing sharp facial pain on descent that can distract a pilot or force an early return to the airport.
Grounding Statement
Picture a small air pocket in your cheek that must stay open to the nose so it can adjust as cabin or outside pressure changes.
Intuition Check
Maxillary does not mean “maximum.” It means related to the upper jaw and cheek area. Sinus does not just mean congestion; here it means the actual air-filled space that can become painful if pressure is trapped.
Example Sentence 1
The pilot delayed the flight after a head cold, knowing that a blocked maxillary sinus could cause severe pain on descent.
Example Sentence 2
A head cold had inflamed the maxillary sinus, so the instructor advised against flying until the swelling subsided.