The cerebrum is the largest part of the brain: the two cerebral hemispheres that sit on top of the brainstem, split down the middle by the longitudinal fissure. Its wrinkled outer layer is the cerebral cortex, lit here in one colour as the five lobes of each hemisphere. [1][2]
The 3D brain needs JavaScript. The text below still says where the cerebrum is and what it does.
Slice
They are all lit together; the side (sagittal) slice button cuts down the midline through them. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
The 3D model has no one shape named the cerebrum, so this page lights its cortex: the frontal, parietal, temporal and occipital lobes and the insula of both hemispheres, all in one colour (the lobes page gives each its own). The insula is lit too but sits hidden under the other lobes, as in a real brain. The cerebrum’s deep parts, such as the hippocampus and the basal ganglia, and its white matter are left dark; they are lit on their own pages. [1][3][4]
It fills the top and front of the skull: it overlies the other brain structures, sits on the brainstem and lies above the cerebellum, from which a sheet of dura, the tentorium cerebelli, separates it. [5][6]
A deep groove, the longitudinal fissure, splits it into nearly symmetrical left and right cerebral hemispheres; the corpus callosum, the largest of the bundles crossing that groove, joins them. [5][2]
Grey and white matter: the cortex is grey matter, made of nerve-cell bodies and 2 to 4 mm thick; beneath it lies the cerebral white matter, bundles of nerve fibres, with deep grey-matter nuclei such as the basal ganglia set inside it. [5][7][1]
The cortex is folded into ridges (gyri) and grooves (sulci): about two thirds of its surface is buried in the grooves and the insula is hidden completely. Peeled off and laid flat, it would cover roughly one square metre. [3][2]
What it does
Many of the higher functions, such as memory, emotion and consciousness, are the result of cerebral function; the cortex is the part responsible for the higher functions of the nervous system. [2]
Cortical areas have set jobs: movement in the motor cortex, sight in the visual cortex; making speech is credited to Broca’s area in the frontal lobe and understanding it to Wernicke’s area where the temporal and parietal lobes meet. [3][1]
Share of the brain: the cerebrum is the largest part, and its cortex alone makes up about 40% of the brain’s mass. Yet the cortex holds only about 16 billion neurons (19%), while the far smaller cerebellum holds about 69 billion (80%). [3][5]
Layers: about 90% of the cortex is the neocortex, which has six layers of neurons; the rest, the allocortex, has three or four. [3][5]
Other names
Telencephalon, or endbrain, is its other name: it grows from the front part of the embryo’s forebrain, whose upper side becomes the cerebral cortex and lower side the basal ganglia. [1]
Cerebral cortex (also cerebral mantle) names its outer layer of nerve tissue; it is the part this model draws, so it is what is lit here. [3]
Size
On this model the cerebrum together fit in a box about 180 mm front to back, 117 mm top to bottom and 141 mm side to side (the box they fit in, not their volume). [4]
Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.