Plain English Meaning

Hollow spaces inside your cheekbones that are connected to your nose by tiny passages. They normally let air flow in and out so the pressure inside matches the air around you. When you have a cold and the passages get blocked, the air can get trapped and cause sharp pain when you climb or descend.

Full Definition

Air-filled cavities located within the cheekbones on either side of the nose, connected to the nasal passages by small openings. As one of the paranasal sinuses, they must equalize pressure with the surrounding atmosphere during climbs and descents; if the connecting opening is blocked by congestion, trapped air cannot expand or contract freely, causing pain and possible incapacitation in flight.

Context Anchor

Seen in aeromedical discussions about sinus pain, head colds, allergies, and flying during climbs or descents.

Derivation

From Latin maxilla meaning 'jawbone' or 'upper jaw.' These sinuses sit in the bone of the upper jaw, just below the eyes and beside the nose — hence the name.