Recto: A page from a notebook showing the dissection of a pregnant cow. The drawings show the two-chambered bovine uterus, with a calf in the upper chamber. In the lower study Leonardo removes the uterine wall to show the calf; the placenta is represented as a pattern of small ovals.

Verso: Leonardo wrote at the head of this page ‘the motor muscles of the lips of the mouth’, and most of the studies examine the muscles that pull the mouth into a wide range of expressions – naturally, of great interest to an artist. At centre left is a sketch of the bovine uterus, studied in more detail on the other side of the sheet.

Following his first forays in the study of anatomy around 1490, Leonardo returned to the subject late in life. He intended to publish an illustrated treatise on the subject, but this was never completed.

Text adapted from Leonardo da Vinci, A life in drawing, London, 2018