The bulla ethmoidalis: lamella or a true cell?

The anterior ethmoidal region, including the bulla ethmoidalis, is the most common area addressed during functional endoscopic sinus surgery. Therefore, a detailed understanding of the bulla is essential for safe and effective surgery.

Based on a review of historical articles on sinus anatomy and review of the current understanding of sinonasal embryology, it is suggested that the ethmoidal bulla is a "lamella" structure rather than a "cell," as it is widely accepted to be.

To analyze the anatomic conformation and nature of the ethmoidal bulla.

Detailed gross anatomic sagittal dissection of 14 sinonasal complexes with special attention to the ethmoidal bulla and surrounding structures and pneumatization tracts.

The ethmoidal bulla consisted of a distinct bony lamella in all cases. The degree of development and pneumatization was variable, ranging from a rudimentary torus to a relatively well-pneumatized "bulla"-like structure. A pneumatization tract originating from the retrobullar recess was present in all specimens. This pneumatization excavated into the lamella, creating the bulla-like appearance as viewed from the middle meatus. However, the bulla was not a discrete individual ethmoid cell as it did not have a complete or discrete posterior bony wall. Rather, the posterior wall of this pneumatization tract was formed by the basal lamella.

The ethmoidal bulla lacks a distinct posterior wall and therefore is not a separate cell but rather a bony lamella with an air space behind it. From an anatomic perspective, bulla is perhaps not the best term for this structure.