Ethmoidal infundibulum

The ethmoidal infundibulum is a funnel-shaped/slit-like/curved' opening/passage/space/cleft' upon the anterosuperior portion of the middle nasal meatus at the hiatus semilunaris'. The anterior ethmoidal air cells,' and the frontonasal duct open into the ethmoidal infundibulum. The ethmoidal infundibulum extends anterosuperiorly from its opening into the nasal cavity.''''''

Anatomy

The ethmoidal infundibulum is bordered medially by the uncinate process of the ethmoid bone, and laterally by the orbital plate of the ethmoid bone. Hiatus semilunaris and hiatus maxillaris are covered by a layer of tissue and therefore the ethmoidal infundibulum is the folloving part of the "tunnel" leading to meatus nasi medius.
The ethmoid infundibulum leads towards the maxillary hiatus.The anterior ethmoidal cells open into the anterior part of the infundibulum.''''''

Variation

The frontonasal duct may or may not drain into the ethmoidal infundibulum - this is determined by the place of attachment of the uncinate process of the ethmoid bone: if the uncinate process is attached to the lateral nasal wall, the frontonasal duct will open directly into the middle nasal meatus; if otherwise, it will drain into the infundibulum. In slightly over 50% of subjects, it is directly continuous with the frontonasal duct. When the anterior end of the uncinate process fuses with the anterior part of the bulla, however, this continuity is interrupted and the frontonasal duct then drains directly into the anterior end of the middle meatus.''''''