<prompt> Vertical crest in fundus of the internal auditary canal is ka:Bills barPonticulusCogFalciform crest  <response>: Ans is a i.e. Bills Bar The internal acoustic canal is divided by transverse crest or falciform crest into a superior and inferior Part. The superior part is divided by vertical crest or Bills bar into anterior and posterior parts. Antero-superior part transmits-facial nerve and nervus intermediusPostero-superior part transmits-superior vestibular nerveInferior part transmits-- cochlear nerve lying antero- inferiorly - inferior vestibular nerve postero-inferiorly Bills bar is used as a surgical landmark for facial nerve identification during Trans labyrinthine surgery. 