I hesitate to write this because the answer is so mundane, but: it's an illustration in a medical text. Specifically, the manuscript is "shelfmarked" Besançon, Bibliothèque municipale, MS 0457: that tells us the city it's currently in, the library it's at, that it's a manuscript (MS; plural is MSS), and then its identifying number. (Larger libraries have more complicated numbering systems, but the basic format is standard). This particular manuscript was copied and illuminated in the later 13th century, probably in Paris. It is a Latin translation of Avicenna's Canon medicinae, one of THE most important medical texts that the later medieval Latin west absorbed from the Arab world.

You can see some other illuminations from this manuscript, including a grody caesarean section (always meaning the death of the mother, which had already occurred; usually an emergency procedure to ensure the baby can be baptized before it also dies), here.