All of the following form the floor of third ventricle, except
Floor of third ventricle is formed from before backward by :Optic chiasmaTuber cinerum & infundibulumMammillary bodiesPosterior perforated substanceTegmentum of midbrain(Ref: Vishram Singh textbook of clinical neuroanatomy second edition pg 137)
Infundibulum
Occulomotor nerve
Mammillary body
Optic chiasma
Brain 