<prompt> The valve of Hasner isOpening of nasolacrimal ductSphenoidal sinus openingFrontal sinus openingEthmoidal sinus opening  <response>: Nasolacrimal duct NLD opens into the Inferior meatus through the Hasners valve.The direction of NLD--downward, backward, and laterally from the lacrimal sac to the nose, Length- 1.8 cmSphenoid sinus and posterior ethmoids open into the sphenoethmoidal recess Superior meatusFrontal, Maxillary and Anterior ethmoids open into the middle meatus.Ref: Hazarika; 3rd ed; Pg 240 