Which of the following is NOT a component of the telencephalon?

• A. Thalamus
• B. Cerebral cortex
• C. Limbic system
• D. Basal ganglia

Answer: (A)

This item tests how the forebrain is divided embryologically into the telencephalon versus the diencephalon. The telencephalon forms the cerebral hemispheres and includes the cerebral cortex, the basal ganglia, and many limbic-system structures like the hippocampus and amygdala. The thalamus, however, sits in the diencephalon, a separate forebrain region that lies between the brainstem and the cortex and acts as a major relay for sensory and motor information. Because the thalamus belongs to the diencephalon, it is not a component of the telencephalon. So the structure that does not belong to the telencephalon is the thalamus, while the other listed structures are telencephalic.