There was a very interesting article in the Mayo Clinic Proceedings several years ago which presented a "medical interpretation" of Michaelangelo's The Creation of Adam.
A man of many talents, Michelangelo’s proficiency in anatomical dissection is reflected in his artwork... we see a postpartum uterus and adjacent anatomy, justifying our interpretation that Michelangelo was depicting something far more fundamental: the birth of mankind.Details of the interpretation at the link, including a comparison of God's "oval" to 16th century depictions of the uterus. Michaelangelo had extensive experience in dissecting and depicting the human body organs.
There are, of course, numerous other depictions of Adam in paintings and sculpture that depict him with a navel that theoretically should not exist.
