Vertical crest in fundus of the internal auditary canal is k/a:

Ans is 'a' i.e. Bill's 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 Bill's 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 Bill's bar is used as a surgical landmark for facial nerve identification during Tran's labyrinthine surgery.