The valve of Hasner is: (A) Opening of nasolacrimal duct, (B) Sphenoidal sinus opening, (C) Frontal sinus opening, (D) Ethmoidal sinus opening
Answer is A. Nasolacrimal duct (NLD) opens into the Inferior meatus through the Hasner`s 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 meatus)Frontal, Maxillary and Anterior ethmoids open into the middle meatus.Ref: Hazarika; 3rd ed; Pg 240