The cerebrum is a large part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. In the human brain, the cerebrum is the uppermost region of the central nervous system. The prosencephalon is the embryonic structure from which the cerebrum develops prenatally. In mammals, the dorsal telencephalon, or pallium, develops into the cerebral cortex, and the ventral telencephalon, or subpallium, becomes the basal ganglia. The cerebrum is also divided into approximately symmetric left and right cerebral hemispheres.
With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the body.
Structure
The cerebrum is the largest part of the brain. Depending upon the position of the animal it lies either in front or on top of the brainstem. In humans, the cerebrum is the largest and best-developed of the five major divisions of the brain.
The cerebrum is made up of the two cerebral hemispheres and their cortices, (the outer layers of grey matter), and the underlying regions of white matter.[1] Its subcortical structures include the hippocampus, basal ganglia and olfactory bulb. The cerebrum consists of two C-shaped cerebral hemispheres, separated from each other by a deep fissure called the longitudinal fissure.
Cerebral cortex
Surface of the cerebrum
The cerebral cortex, the outer layer of gray matter of the cerebrum, is found only in mammals. In larger mammals, including humans, the surface of the cerebral cortex folds to create gyri (ridges) and sulci (furrows) which increase the surface area.[2]
The cerebral cortex is generally classified into four lobes: the frontal, parietal, occipital and temporal lobes. The lobes are classified based on their overlying neurocranial bones
Cerebral hemispheres
The cerebrum is divided by the medial longitudinal fissure into two cerebral hemispheres, the right and the left. The cerebrum is contralaterally organized, i.e., 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.[3] There is a strong but not complete bilateral symmetry between the hemispheres. The lateralization of brain function looks at the known and possible differences between the two.
Development
In the developing vertebrate embryo, the neural tube is subdivided into four unseparated sections which then develop further into distinct regions of the central nervous system; these are the prosencephalon (forebrain), the mesencephalon (midbrain) the rhombencephalon (hindbrain) and the spinal cord.[4] The prosencephalon develops further into the telencephalon and the diencephalon. The dorsal telencephalon gives rise to the pallium (cerebral cortex in mammals and reptiles) and the ventral telencephalon generates the basal ganglia. The diencephalon develops into the thalamus and hypothalamus, including the optic vesicles (future retina).[5] The dorsal telencephalon then forms two lateral telencephalic vesicles, separated by the midline, which develop into the left and right cerebral hemispheres. Birds and fish have a dorsal telencephalon, like all vertebrates, but it is generally unlayered and therefore not considered a cerebral cortex. Only a layered cytoarchitecture can be considered a cortex.