Brain
Corpus Callosum
The great bridge between hemispheres
Overview
The corpus callosum is the largest white matter structure in the brain, containing around 200–250 million nerve fibers. It bridges the left and right cerebral hemispheres, enabling them to share information and coordinate activity. Without it, the two hemispheres function largely independently—as seen in "split-brain" patients.
Function
- Transfers sensory, motor, and cognitive information between hemispheres
- Coordinates voluntary movement across the body's midline
- Enables unified perceptual experience
- Integrates language and spatial processing between hemispheres
- Facilitates bimanual coordination
Key Facts
- Split-brain patients (corpus callosum severed) show two near-independent cognitive systems
- The corpus callosum is the last brain structure to fully myelinate (~age 25)
- Women's corpus callosum is proportionally larger than men's on average
- Ancient brain surgeons occasionally severed it to treat severe epilepsy (callosotomy)