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
Floor of middle ear cavity is in relation with: 
Select and explain. 
A. Internal carotid artery, B. Bulb of the internal jugular vein, C. Sigmoid sinus, D. Round window
B: Bulb of the internal jugular vein
Answer: B: Bulb of the internal jugular vein 
Explanation: (b) Bulb of the internal jugular vein(Ref. Cummings, 6th ed., 1983)The floor of middle ear cavity is a thin plate of bone separating the middle ear from jugular bulb below.Internal carotid artery is in relation to the anterior wall of middle ear.Sigmoid sinus is not related directly with middle ear cavity. It lies posterior to the mastoid antrum.Round window lies postero-inferiorly on the medial wall of middle ear.