Midbrain tegmental lesions affecting or sparing the pupillary fibres.

Two patients with oculomotor palsy caused by midbrain infarction are reported. In the first, pupillary reaction was affected and in the second this reaction was spared. Because the lesions in the anterior part of the tegmentum were in the upper midbrain in the first patient and in the lower midbrain in the second, it is suggested that the pupillary components of the oculomotor nerve are located in the upper midbrain.