Horizontal section of right cerebral hemisphere. (Capsula interna labeled at upper left.)
Diagram of the tracts in the internal capsule. Motor tract red. The sensory tract (blue) is not direct, but formed of neurons receiving impulses from below in the thalamus and transmitting them to the cortex. The optic radiation (occipitothalamic) is shown in violet.
The fibers in the region of the genu are named the geniculate fibers; they originate in the motor part of the cerebral cortex, and, after passing downward through the base of the cerebral peduncle with the cerebrospinal fibers, undergo decussation and end in the motor nuclei of the cranial nerves of the opposite side.
It is formed by fibers from the corticonuclear tracts.