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
Vertical crest of bone in the internal acoustic meatus is: 
Select and explain. 
A. Bill's bar, B. Ponticulus, C. Cog, D. Falciform crest
A: Bill's bar
Answer: A: Bill's bar 
Explanation: (a) Bill's bar(Ref. Shambaugh, 6th ed., page 42)Ponticulus is a ridge which runs from the oval window to the sinus tympani forming its superior extent.Cog is a bony projection from the roof of middle ear, i.e. tegmen tympani to the processus cochleariformis, serving as an approximate landmark for the facial nerve.Falciform crest divides the internal acoustic meatus into a superior and inferior part.