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a bulging of the inner wall of the ethmoidal labyrinth in the middle meatus of the nose, just below the middle nasal concha; it is regarded as a rudimentary concha.
Synonym(s): bulla ethmoidalis [TA]
A rounded, thin-walled, bony projection into the middle meatus of the nose underneath the middle turbinate bone, formed by an anterior ethmoid sinus.
See also: bulla