Mondino's treatment of the skull provides only inexact directions for its dissection, suggesting that the cranial cavity was opened infrequently and with little technical skill. Nonetheless, "Anathomia" contains a description of the cranial nerves derived from Galen's "Uses of the parts of the body of man". Furthermore, the brain is divided into three vesicles, with the anterior vesicle serving as the meeting place of the senses, the middle vesicle housing the imagination, and the posterior vesicle containing the memory. Movement of the choroid plexus is said to control mental processes by opening and closing passages between the ventricles. Mondino follows Galen and the Islamic commentators in placing the lens in the center of the eye.