Walsh & Hoyt: Embryology

The telencephalon develops at about 6 weeks of gestation from the most anterior aspect of the prosencephalon as bilateral evaginations, the walls of which develop into the cerebral hemispheres. The superior portions of the walls develop into the pallium, or primordium of the cerebral cortex. In humans, the largest portion of the pallium is the neopallium, from which arise the visual cortices