Radiation of corpus callosum

The radiation of corpus callosum (a.k.a. radiatio corporis callosi) is the broad, fan-shaped arrangement of commissural fibres that spreads laterally from the corpus callosum into the white matter of each cerebral hemisphere after the fibres cross the midline.

• Fibres from the genu curve anteriorly into the frontal lobes, with the prominent curved bundle forming the forceps minor.

• Fibres from the body radiate laterally, particularly into the frontal and parietal white matter.

• Fibres from the splenium spread posteriorly towards the posterior temporal and occipital regions; those curving posteriorly into the occipital lobes form the forceps major.

• Some callosal fibres sweep laterally and inferiorly to form the tapetum, a thin sheet of commissural fibres that descend along the outer aspect of the walls of the posterior and inferior horns of the lateral ventricle.

Collectively, the radiation of the corpus callosum distributes callosal fibres to widespread cortical regions, enabling interhemispheric communication and integration.

Important distinction

The callosal radiation consists of commissural fibres, whereas the corona radiata consists predominantly of projection fibres that converge towards or diverge from the internal capsule.