The pretectal nuclear complex and the accessory optic system.

A critical survey of the nomenclatures used for subdivisions of the pretectal nuclear complex is followed by a description of pretectal development and connectivity of individual nuclei. Some of these mediate the pupillary light reflex; part of another forms part of the accessory optic system, involved in processing visual signals for the generation of compensatory (optokinetic) eye movements. The anatomy, development, connections and function of the accessory optic system and its subdivisions are reviewed.