Which brain structure connects the left and right cerebral hemispheres?

The corpus callosum connects the left and right cerebral hemispheres.

It is a broad, C-shaped bundle of more than 200 million nerve fibres in the human brain. Most of these fibres are myelinated axons, allowing electrical signals to travel between corresponding and related areas of the two cerebral hemispheres.

The corpus callosum supports interhemispheric communication, helping the brain combine information from both sides. It is commonly divided into regions including the rostrum, genu, body, and splenium. Different regions connect different cortical areas, with the splenium especially associated with posterior visual and sensory connections.

The hemispheres are not completely independent, and popular claims that people are simply “left-brained” or “right-brained” oversimplify neuroscience. Damage or surgical separation of callosal connections can produce split-brain effects in carefully designed tasks, but everyday brain function normally depends on extensive cooperation. The corpus callosum is the largest commissural fibre tract in the brain, while smaller commissures connect other regions.