The term Nucleus pulvinaris medialis internus (Hassler) refers to a substructure of the medial pulvinar nucleus of the thalamus. It, the Nucleus pulvinaris medialis dorsalis (Hassler), the Nucleus pulvinaris medialis zentralis (Hassler) and the Nucleus pulvinaris medialis ventralis (Hassler) constitute the Nucleus pulvinaris medialis (Hassler) ( Jones-1990 ).