The cerebrum, also known as the telencephalon, is the largest and most highly developed part of your brain. It encompasses about two-thirds of the brain mass and lies over and around most of the structures of your brain. The word cerebrum comes from Latin cerebrum, meaning "brain."
The cerebrum is divided into right and left hemispheres that are connected by an arch of white matter called the corpus callosum. The cerebrum is contralaterally organized, which means that the right hemisphere controls and processes signals from the left side of the body, while the left hemisphere controls and processes signals from the right side of the body.
The cerebrum is the part of the brain responsible for your high functions, including:
- Determining intelligence
- Determining personality
- Producing and understanding language
- Interpretation of sensory impulses
- Motor function
- Planning and organization
- Processing sensory information
The outer portion of your cerebrum is covered by a thin layer of gray tissue called the cerebral cortex. This layer is 1.5 to 5 millimeters in thickness. Your cerebral cortex is in turn divided into four lobes: frontal lobes, parietal lobes, temporal lobes, and occipital lobes. Your cerebrum, along with the diencephalon, which includes the thalamus, hypothalamus, and the pineal gland, comprises the two major divisions of the prosencephalon (forebrain).
Your cerebral cortex handles a number of the most important brain functions. Among these functions is the processing of sensory information by the cortex lobes. Limbic system brain structures located beneath the cerebrum also assist in sensory information processing. These structures include the amygdala, thalamus, and hippocampus. Limbic system structures use sensory information to process emotions and connect your emotions with memories.
Your frontal lobes are responsible for complex cognitive planning and behaviors, language comprehension, speech production, and the planning and control of voluntary muscle movement. Nerve connections with the spinal cord and brainstem allow the cerebrum to receive sensory information from your peripheral nervous system. Your cerebrum processes this information and relays signals that produce the appropriate response.
Directionally, your cerebrum and the cortex that covers it is the uppermost part of the brain. It is the anterior portion of the forebrain and is superior to other brain structures such as the pons, cerebellum, and medulla oblongata. Your midbrain connects the forebrain to the hindbrain. Your hindbrain regulates autonomic functions and coordinates movement.
With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the body.
The cortex is made up of coils and twists. If you were to spread it out, it would actually take up about 2 1/2 square feet. It is estimated that this part of the brain is made up of 10 billion neurons, which are responsible for brain activity that equals up to 50 trillion synapses.
The brain's ridges are called "gyri," and valleys which are called sulci. Some of the sulci are quite pronounced and long and serve as convenient boundaries between the four lobes of the cerebrum.