In the study of anatomy, we have become accustomed to thinking that anatomy is a "non-evolving" science and that one’s knowledge of the human body is completed and full by the end of one’s university studies. In actual fact, it is a science that is constantly evolving, so much so that in recent years new elements have been uncovered that before were unknown. For example, it would seem that the quadriceps muscle does not actually consist of four heads, but of five, or so at least in a certain proportion of individuals. An interesting curiosity.