This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
Which structure prevents spread of infection from middle ear to brain 
Select and explain. 
A. Tegmen tympani, B. Cribriform plate, C. Fundus tympani, D. Petrous apex
A: Tegmen tympani
Answer: A: Tegmen tympani 
Explanation: Tegmen tympani forms the roof of the middle ear and it also extends posteriorly to form a roof of aditus and antrum. Reference: Dhingra 6th edition