Middle meatus
Encyclopedia
The middle meatus is a nasal opening or canal situated between the middle and inferior conchæ, and extends from the anterior to the posterior end of the latter.
The lateral wall of this meatus can be satisfactorily studied only after the removal of the middle concha.
On it is a curved fissure, the hiatus semilunaris
, limited below by the edge of the uncinate process
of the ethmoid and above by an elevation named the bulla ethmoidalis; the middle ethmoidal cells are contained within this bulla and open on or near to it.
Through the hiatus semilunaris the meatus communicates with a curved passage termed the infundibulum
, which communicates in front with the anterior ethmoidal cells and in rather more than fifty percent of skulls is continued upward as the frontonasal duct
into the frontal air-sinus; when this continuity fails, the frontonasal duct opens directly into the anterior part of the meatus.
Below the bulla ethmoidalis and hidden by the uncinate process of the ethmoid is the opening of the maxillary sinus
(ostium maxillare); an accessory opening is frequently present above the posterior part of the inferior nasal concha.
The lateral wall of this meatus can be satisfactorily studied only after the removal of the middle concha.
On it is a curved fissure, the hiatus semilunaris
Hiatus semilunaris
The hiatus semilunaris is a crescent-shaped groove in the lateral wall of the nasal cavity just inferior to the ethmoidal bulla. It is the location of the openings for the frontal sinus, maxillary sinus, and anterior ethmoidal sinus...
, limited below by the edge of the uncinate process
Uncinate process
Uncinate process can refer to:* Uncinate process of ethmoid bone* Uncinate process of vertebra - a hook shaped process on the lateral borders of the superior surface of the vertebral bodies of the third to the seventh cervical vertebrae....
of the ethmoid and above by an elevation named the bulla ethmoidalis; the middle ethmoidal cells are contained within this bulla and open on or near to it.
Through the hiatus semilunaris the meatus communicates with a curved passage termed the infundibulum
Infundibulum
An infundibulum is a funnel-shaped cavity or organ.* Lungs: The alveolar sacs of the lungs from which the air chambers open are called infundibula...
, which communicates in front with the anterior ethmoidal cells and in rather more than fifty percent of skulls is continued upward as the frontonasal duct
Frontonasal duct
The frontal air sinuses are lined by mucous membrane, and each communicates with the corresponding nasal cavity by means of a passage called the frontonasal duct....
into the frontal air-sinus; when this continuity fails, the frontonasal duct opens directly into the anterior part of the meatus.
Below the bulla ethmoidalis and hidden by the uncinate process of the ethmoid is the opening of the maxillary sinus
Maxillary sinus
The pyramid shaped maxillary sinus is the largest of the paranasal sinuses, and drains into the nose. It is present at birth as rudimentary air cells, and develops throughout childhood.-General characteristics:...
(ostium maxillare); an accessory opening is frequently present above the posterior part of the inferior nasal concha.