The ethmoid bulla (or ethmoidal bulla) is an elevation on the lateral wall of the middle meatus of the nose. It is produced by middle ethmoidal cells. It develops during the first trimester of gestation, and varies significantly based on the size of air cells.
【Structure】
The ethmoid bulla is on the lateral wall of the middle meatus of the nose. It is produced by middle ethmoidal cells, which are contained within this bulla, and open on or near to it (often just below it).
Just below the bulla is a curved fissure, the hiatus semilunaris. The maxillary sinus also opens below the bulla. It is the largest among the middle ethmoidal cells.
【Development】
The ethmoid bulla begins to develop between 8 weeks and 12 weeks of gestation.
【Variation】
The size of the bulla varies with that of its contained cells. The bulla may be a pneumatised cell or a bony prominence found in middle meatus.
【 語 句 】
・middle meatus of the nose：中鼻道 ・middle ethmoidal cells：中篩骨蜂巣 ・first trimester：妊娠初期 ・gestation：懐胎 ・hiatus semilunaris：半月裂孔 ・maxillary sinus：上顎洞 ・pneumatized：含気性の ・prominence：突出部
