Posterior Commissure
The posterior commissure and the habenular commissure
are small fiber bundles traversing the midline that connect caudal parts of the diencephalon. The former
crosses the midline at the base of the pineal gland and just posterior (dorsal) to the cerebral aqueduct. The latter is a small fascicle running along the upper aspect of the posterior commissure
and interconnecting the habenular nuclei.