What is Corpus callosum?
{{Infobox brain | Name = Corpus callosum | Latin = | Image = Gray733.png | Caption = Corpus callosum from above. (Anterior portion is at the top of the image.) | Image2 = Gray720.png | Caption2 = [[anatomical terms of location|Median sagittal]] section of brain (person faces to the left). Corpus callosum visible at center, in light gray | IsPartOf = [[Human brain]] | Components = Genu, trunk, splenium | Artery = | Vein = }} The '''corpus callosum''' is part of the brain in humans and other [[eutherian mammal]]s. It is the largest connective pathway in the brain. Its over 200 million [[Nerve|nerve fibers]] connect the left and right hemispheres of the brain. The corpus callosum relates to the [[lateralization of brain function]]. Because the two side of the brain communicate so intensively, they can afford to specialise in doing somewhat different things.<ref>Caminiti, Roberto ''et al'' 2009. Evolution amplified processing with temporally dispersed slow neuronal connectivity in primates. ''Proceedings of the National Academy of Sciences'' '''106''' (46): 19551–6. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2770441/]</ref> == Only in higher mammals == The corpus callosum is found only in [[placental mammal]]s (the [[eutheria]]ns). It is absent in [[monotreme]]s and [[marsupial]]s,<ref>{{cite journal |bibcode=1933PNAS...19..609K |jstor=86284 |title=Absence of the corpus callosum as a mendelizing character in the house mouse |last1=Keeler |first1=Clyde E. |volume=19 |year=1933 |pages=609–11 |journal=Proceedings of the National Academy of Sciences of the United States of America |doi=10.1073/pnas.19.6.609 |pmid=16587795 |issue=6 |pmc=1086100|doi-access=free }}</ref> and other vertebrates such as birds, reptiles, amphibians and fish.<ref>Sarnat, Harvey B. and Paolo Curatolo 2007. Malformations of the nervous system in ''Handbook of Clinical Neurology'', [https://books.google.com/books?id=7InmnW9ul7gC&pg=PA68 p. 68]{{Dead link|da