Which valve is present at opening of nasolacrimal duct-: (A) Hasner's valve, (B) Heister valve, (C) Spiral valve, (D) None
Answer is A. Ans. is 'a' i.e., Hasner's valve o Nasolacrimal duct opens into inferior meatus and is closed by a mucosal flap called Hasner's valve,o Heister valve (spiral valve) is present in cyclic duct.