<prompt> Floor of third ventricle is formed by all exceptTuber cinereumPosterior perforated substanceTegmentumAnterior pituitary  <response>: The floor is formed from before backwards by:Optic chiasmTuber cinereumInfundibulumMamillary bodiesPosterior perforated substanceTegmentum of midbrainRef: Vishram Singh textbook of clinical neuroanatomy second edition pg 137 