What makes up the bulk of the brain?

The cerebrum makes up the bulk of the brain and is responsible for various higher brain functions, including thought processes, voluntary muscle movements, and sensory perceptions. It is the largest part of the brain, encompassing approximately 85% of its total mass, and is divided into two hemispheres. Each hemisphere is further divided into lobes that manage specific functions, such as the frontal lobe for decision-making and problem-solving, the temporal lobe for auditory processing, the occipital lobe for vision, and the parietal lobe for sensory information processing.

In contrast, the cerebellum, while important for coordination and balance, constitutes a smaller portion of the brain's total mass and is located at the back of the brain beneath the cerebrum. The brainstem, which connects the brain to the spinal cord, governs many automatic functions vital for survival, such as breathing and heart rate, but it is also a smaller structure compared to the cerebrum. The thalamus acts as a relay station for sensory information but is again significantly smaller than the cerebrum. Hence, the cerebrum is rightly identified as the part of the brain that forms its bulk.