The hallmark of a supranuclear eye movement disorder is a functional impairment of one or several types of different eye movements while other types of eye movements still work. All eye movement information is conveyed via the nuclei of the eye muscle nerves. However, the information for a specific type of eye movement is generated in prenuclear cortical and subcortical areas which are activated depending on the type of eye movement performed. Knowledge about the anatomy of these areas enables us to make a clinical diagnosis or to localize the pathological process to a specific area in many neurological conditions. Examination of eye movements are thus a valuable clinical tool in many neurological and neuroophthalmological diseases. The first part of this two-part contribution presents the different types of eye movements, the concept of neural integration, and prenuclear structures important for horizontal eye movement as well as the pertinent pathology. The second part will appear in the next issue and deals with the cerebral structures that are relevant for vertical eye movements including their pathology.