The corpus callosum is the great transverse commissure of the cerebrum. It is a transverse band of white matter that spans the longitudinal fissure and connects the hemispheres of the cerebrum for almost half of their length. The falx cerebri touches the posterior portion of the corpus callosum. However, the greater part of the body of the corpus callosum and its anterior extremity are separate for a considerable distance from the falx cerebri. The corpus callosum is between seven to ten centimeters long and extends nearer to the anterior than to the posterior end of the cerebrum. It is wider behind and thicker at each end, especially the posterior extremity. It forms the roof of the lateral ventricle which are cavities located within the hemispheres of the cerebrum. On its dorsal surface, extending along its middle line, there is a linear depression called a raphe. On each side of the raphe, are two slightly elevated longitudinal bands called the nerves of Lancisi. External to these are the faintly marked striae longitudinales laterales or taeniae tectae, which underlie the convolutions of the corpus callosum. These convolutions are called gyri fornicati. The corpus callosum consists of a main portion or body and two extremities, the anterior and posterior.

Corps calleux