The corpus callosum is the largest white matter fiber pathway in the human brain. It comprises over 200 million axons connecting the left and right cerebral hemispheres. The first recorded description of the corpus callosum dates back to the work of philosopher and physician Galen of Pergamon, circa 177 CE. The structure was named corpus callosum (from Latin, meaning “brawny body”) by Dutch anatomist Andreas Vesalius in 1543. The corpus callosum is one of several commissures providing functional coordination between brain hemispheres. Commissural pathways (or commissures) such as the corpus callosum are defined in neuroanatomy as nerve fiber pathways that cross the midline in animals characterized by bilateral symmetry. Most white matter commissures, such as the anterior commissure, are preserved across vertebrates. However, the corpus ...