Intramesencephalic course of the oculomotor nerve fibers: microanatomy and possible clinical significance.

Comprehension of the mesencephalic syndromes that affect oculomotor nerve fascicles requires a detailed knowledge of their relationship with the adjacent structures and the blood supply of the central midbrain region. This was the reasoning behind our study, which was performed in ten serially sectioned midbrains stained with cresyl violet and luxol fast blue, in three microdissected midbrains, and in two injected and cleared specimens. Three continuous groups of the intramesencephalic oculomotor nerve fascicles were distinguished: the caudal, intermediate and rostral.