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a deep, narrow groove in the lateral wall of the middle meatus of the nasal cavity, into which the maxillary sinus, the frontonasal duct, and the middle ethmoid cells open.
The groove in the external wall of the middle meatus of the nasal fossa into which the frontal sinus, maxillary sinus, and anterior ethmoid sinuses drain. The opening may be blocked in patients with acute or chronic sinusitis.
See also: hiatus