The term Nucleus pulvinaris medialis (Hassler) refers to a composite substructure of the thalamus that includes most of the medial pulvinar nucleus. It has four subdivisions: the Nucleus pulvinaris medialis internus (Hassler), the Nucleus pulvinaris medialis dorsalis (Hassler), the Nucleus pulvinaris medialis zentralis (Hassler) and the Nucleus pulvinaris medialis ventralis (Hassler) ( Jones-1990 ).