The agger nasi (from Latin: agger meaning "mound or heap") is a small ridge on the lateral side of the nasal cavity.

It is formed by a mucous membrane that is covering the ethmoidal crest of the maxilla.

It is also called the nasoturbinal concha and the nasal ridge.

In 90% of patients an anterior ethmoidal cell (called the "agger nasi cell") can be found in the lacrimal bone below the agger nasi ridge.

[1] An enlarged agger nasi cell may encroach the frontal recess area, constricting it and causing mechanical obstruction to frontal sinus drainage.