Lancisi's nerves and the seat of the soul.

The striae longitudinales mediales corporis callosi, or medial longitudinal striae of the corpus callosum, are two slender bands of myelinated fibers that form longitudinal ridges in the indusium griseum on the superior aspect of each half of the corpus callosum. They were first described by the Italian physician Giovanni Maria Lancisi, who served as the personal physician of three successive Popes. This essay offers an account of this eminent physician, his era, and his philosophical background, as well as a description of the anatomic structures that bear his name.