This drawing of the human skull has been presented by Leonardo in such a way that the student can see what goes on under the superficial layer of bone structure as well as the whole shape. The skull, cut in two, has the frontal
and maxillary sinuses, the nasal cavity and the roots of the teeth exposed on the side where the wall of the skull has been cut away. All the fissures in the skull visible from this angle are clearly and accurately shown.
As a drawing of the bone structure of the head, it has been universally admired for its accuracy and proportion. Alongside are careful drawings of teeth with their roots shown and numbered. In his notes Leonardo gives the number and position of all the teeth.