<prompt> True about sphenoid sinus:Lined by staified squamous epitheliumDuct open in middle meatusOpen in sphenoethmoid recessPresent at bih  <response>: All paranasal sinuses are lined by respiratory epitheliumi.e option a is incorrect. sphenoid sinus:Impoant points it is not present at bih it occupies the body of sphenoid ostrum of sphenoid sinus is situated in the upper pa of anterior wall and drains intlo spheno ethmoidal recess on x ray sphenoid sinus is visible by 4 years of age. Ref Dhingra 6e,p 188 