Corpus: Corpus callosum

The corpus callosum is a transverse fiber connection (commissure) between the two cerebral hemispheres. Comprising approximately 200 million myelinated nerve fibers, it forms the largest part of the commissural system.

The corpus callosum is divided into several sections: the anterior section (rostrum), the genu, the middle section (trunk), and the thicker posterior section (splenium). The fiber system of the corpus callosum forms the roof of the lateral ventricles. It is covered by a layer of gray matter known as the supracallosal gyrus. The fornix is situated beneath the corpus callosum.

Blood supply to the corpus callosum is provided by the posterior pericallosal artery, a branch of the posterior cerebral artery, and the pericallosal artery, a branch of the anterior cerebral artery. Venous drainage is facilitated by the posterior corpus callosal vein, among others.

The primary function of the corpus callosum is to transmit information between the two cerebral hemispheres. Since both hemispheres have different functions, the coordination of these functions occurs through the exchange of information via the corpus callosum. The corpus callosum contains both homotopic and heterotopic commissural fibers, meaning it connects cortical areas symmetrically as well as asymmetrically. This connectivity is evident in the lateralization of the telencephalon.

The corpus callosum is clinically significant in some forms of epilepsy. Surgical separation of the corpus callosum (callosotomy) is performed to prevent the spread of seizures from one hemisphere to the other. This procedure is particularly indicated for epilepsies with heavy falls, which can lead to serious injuries. Callosotomy can significantly reduce the number of falls. However, due to numerous cognitive side effects and the controversial nature of the procedure, it is rarely performed today.

A congenital insufficiency of the corpus callosum is known as Aicardi syndrome.