Pineal gland forms ?

Ans. is 'c' i.e., Posterior wall of thrid ventricleBoundries of third ventricle are :-Anterior wall : Lamina terminal, anterior commissure, anterior columns of fornix.Posterior wall : Pineal body, posterior commissure, cerebral aqueduct.Roof : Ependyma lining of under surface of tela choroidea of r ventricle. The choroid plexus of third ventricle projects downwards from roof.Floor : Optic chiasma, tuber cinereum, infundibulum (pituitary stalk), mammillary body, posterior perforated substance and tegmentum of midbrain.Optic recess is seen at the junction of floor with anterior wall.Lateral wall : Medial surface of thalamus, hypothalamus and hypothalamic nuclei. Interventricular foramen (of Monro) is seen at the junction of roof with anterior and lateral wall.