<prompt> True regarding cavity of diencephalons isSeptum pellucidum forms paitionSeptum pellucidum cavity opens superiorlyLateral wall is lamina terminalisInter thalamic adhesions join lateral walls  <response>: D i.e. Inter thalamic adhesions join lateral Walls Lamina terminalis is a thin sheet of gay matter, which extend between two hemisphere from rostrum of corpus callosum to top of optic chiasma forming the anterior wall of 3rd ventricle. Septum pellucidum is a thin veical sheet of gray white nervous tissue, which connects corpus callosum rostrum, genu front of body to anterior column of fornix and forms paition between anterior horns of lateral venticles not 3rd ventricle or cavity of diencephalon. Lateral wall of cavity of diancephalon 3rd ventricle is formed by thalmus, hypothalmus, hypothalmic sulcus subthalmus. 