Disturbances in eye movements can provide important clues for localization of neurological damage. The role of the frontal eye fields in horizontal gaze is stressed. The need to coordinate cranial nerves on both sides of the brain stem introduces the medial longitudinal fasciculus and its role in coordinating CN 3 and 6. Interruption of this pathway results in internuclear ophthalmoplegia and nystagmus both of which are demonstrated with a clinical video.
