Ethmoidal Bulla, Inferior View

Description

Ethmoidal bulla dominates this inferior perspective of the ethmoidal labyrinth as a smooth, rounded prominence created by the middle ethmoidal air cells. Positioned lateral to the middle nasal concha and superior to the middle meatus, its convex surface forms the superior boundary of the hiatus semilunaris, while the uncinate process lies anteroinferior to it as a thin, sickle-like lamella. Medially, the bulla faces the nasal cavity; laterally it approaches the lamina papyracea of the orbit, a relationship that is easy to appreciate from below. Endoscopic sinus surgery often begins by identifying the bulla as a consistent landmark when entering the anterior ethmoid, then working around the ethmoidal infundibulum, frontal recess, and the natural ostium region of the maxillary sinus along the semilunar hiatus. Mistaking the bulla for adjacent partitions or violating its lateral boundary can place the orbit at risk, while incomplete opening of the bulla may leave obstructed ethmoidal cells that perpetuate chronic rhinosinusitis. Lighting and surface definition in this fixed view help separate the bulla’s rounded contour from the sharper edge of the uncinate process, clarifying the corridor that functional endoscopic sinus surgery follows in the middle meatus. A tight space. Use this illustration in ENT and head and neck anatomy courses to teach middle meatal landmarks, or in surgical atlases and patient-facing materials explaining ethmoidectomy and frontal recess access; it also pairs well with coronal CT teaching sets when correlating the ethmoid bulla and ostiomeatal complex. Anatomical accuracy verified by SciePro's Medical Advisory Board.