The telencephalon is the embryonic brain division that develops into the cerebral hemispheres and basal ganglia.
Early in human development, the neural tube forms major primary brain vesicles. The forebrain, or prosencephalon, divides into the telencephalon and diencephalon. The paired telencephalic vesicles expand dramatically and give rise to the cerebral hemispheres, including their cerebral cortex and much of their underlying white matter.
The telencephalon also contributes to deep structures such as the basal ganglia, which participate in movement selection and other circuits. Its growth and folding help produce the characteristic large, convoluted cerebrum of the mature human brain.
The neighboring embryonic divisions have different major outcomes. The diencephalon contributes to structures including the thalamus and hypothalamus, while the mesencephalon becomes the midbrain. The metencephalon contributes to the pons and cerebellum, making these names easy to confuse without the developmental sequence.