Nucleus of posterior commissure

The nucleus of posterior commissure is a group of neuronal cell bodies located in the dorsal rostral midbrain/pretectal region, closely associated with the posterior commissure near the junction between the diencephalon and midbrain.

It should be distinguished from the posterior commissure itself, which is a bundle of predominantly crossing nerve fibres.

The nucleus and surrounding posterior commissural region participate in visuomotor pathways, particularly those involved in the coordination of vertical eye movements. These pathways interact with nearby vertical-gaze centres, including the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) and interstitial nucleus of Cajal.

Clinical correlates

Lesions involving the posterior commissural and adjacent dorsal midbrain region can produce vertical gaze abnormalities, particularly impaired upward gaze, and may be associated with pupillary disturbances in dorsal midbrain (Parinaud) syndrome (due to damage to nearby olivary pretectal nuclei).