In human neuroanatomy, the longitudinal striae are two bundles of fibres embedded in the indusium griseum running along the corpus callosum of the brain. They were originally described by Italian physician, epidemiologist and anatomist Giovanni Maria Lancisi. The striae are categorized as medial longitudinal stria and lateral longitudinal stria; the area between the striae is a useful neurosurgical mark of the middle of the corpus callosum.