The brain's wiring
Cerebral white matter and corpus callosum · substantia alba
The bundles of insulated nerve fibres that connect the different parts of your brain.
What it does
Beneath the wrinkled outer grey matter, the brain is filled with white matter, millions of nerve fibres wrapped in fatty insulation called myelin, which makes them look white. They carry signals between areas of the brain and down to the spinal cord. The corpus callosum is a thick bridge of fibres joining the two halves.
Surprising fact
The corpus callosum contains around 200 million nerve fibres, and people in whom it has been cut can show signs of each half of the brain acting separately.
Why it matters
Multiple sclerosis damages the insulation on these fibres, slowing signals and causing symptoms that come and go in different parts of the body.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.