The lamina terminalis forms the anterior wall of the third ventricle.
It is a thin membrane which stretches between the anterior commissure, the fornix and the rostrum of the corpus callosum. The dorsal surface of the optic chiasm is at the base of the lamina terminalis 1.
It is formed from the rostral end of the neural tube. Early in development, crossing fibres from each cerebral ventricle form together in the lamina terminalis to create the anterior commissure 2.