This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Anatomy
Valve of Rosenmuller is located at 
Select and explain. 
A. Cystic duct, B. Opening of nasolacrimal duct, C. Junction of lacrimal sac and canaliculus, D. Ampulla of vater
C: Junction of lacrimal sac and canaliculus
Answer: C: Junction of lacrimal sac and canaliculus 
Explanation: A fold of mucous membrane found at the junction between the common canaliculus and the lacrimal sac. It is not strictly a valve because fluids can be blown back to emerge at the puncta. It is not always fully developed. ref -medscape.com