E D Wright1, W E Bolger. 1. Department of Otolaryngology, The University of Western Ontario, London.
Abstract
BACKGROUND: 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. HYPOTHESIS: 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. OBJECTIVE: To analyze the anatomic conformation and nature of the ethmoidal bulla. METHODS: Detailed gross anatomic sagittal dissection of 14 sinonasal complexes with special attention to the ethmoidal bulla and surrounding structures and pneumatization tracts. RESULTS: 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. CONCLUSION: 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.
BACKGROUND: 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. HYPOTHESIS: 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. OBJECTIVE: To analyze the anatomic conformation and nature of the ethmoidal bulla. METHODS: Detailed gross anatomic sagittal dissection of 14 sinonasal complexes with special attention to the ethmoidal bulla and surrounding structures and pneumatization tracts. RESULTS: 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. CONCLUSION: 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.