<prompt> The following open in the middle meatus of nose EXCEPT:Maxillary sinusAnterior ethmoidal sinusMiddle ethmoidal sinusPosterior ethmoidal sinus  <response>: Ans. d Posterior ethmoidal sinus. Ref. BD Chaurasia, Human Anatomy- Vol. II, 3rd ed., 197MeatusStructures opening in itFeatures of middle meatus of noseEthmoidal bullaHiatus semilunarisInfundibulumOpening of frontal air sinusOpening of maxillary air sinusOpening of middle ethmoidal air sinusSuperior meatusOpening of posterior ethmoidal air sinusInferior meatusOpening of naso-lacrimal duct guarded by Hasners valve. 