<prompt> Posterior ethmoidal sinus drains into JIPMER May 2019Spheno-ethmoidal recessSuperior meatusMiddle meatusInferior meatus  <response>: - There are 3 groups of ethmoidal air sinuses Anterior Middle Posterior - Posterior ethmoidal sinus is opening in lateral wall of the nose. - Lateral wall of the nose has 3 elevations called superior, middle inferior turbinates conchae - Under each turbinate, there is space called meatus called superior, middle inferior meatus - Posterior ethmoidal sinus is opening in superior meatus - Anterior middle sinus is opening in middle meatus - Middle meatus have hiatus semilunaris At front of hiatus semilunaris frontal air sinus opens The anterior, middle ethmoidal sinus respectively Maxillary sinus opens slightly posterior; In the region of hiatus semilunaris in middle meatus - Naso-lacrimal duct opens in the inferior meatus on Anterior aspect - Inferior turbinate is largest turbinate its meatus is largest meatus - Eustachian tube opens behind inferior turbinate in lateral wall of nasopharynx 