The agger nasi cell: the key to understanding the anatomy of the frontal recess.

The key to successful surgery in the frontal recess is a complete understanding of the anatomy. The frontal recess is behind the beak of the frontal bone between the lamina papyracea and superior portion of the middle turbinate. It is a hazardous and complex area with a range of anatomical configurations. This article describes the anatomy of the frontal recess as it relates to the agger nasi cell using this cell as the key around which the anatomy is built. The simplest anatomical configuration is explained first and this knowledge is built upon so that the more complex configurations can be better understood. The classification of frontal ethmoidal cells by Kuhn is incorporated into the anatomical description of the various configurations. The implication of each anatomical variation on the surgical approach to the frontal recess is discussed.