In Greek mythology, Minos was the king of Crete and was the son of Zeus and Europa. He became one of the three judges of the underworld after his own death and Michelangelo has depicted Minos with ass-ears and wrapped in serpents coils. The coils indicate to what circle of hell the damned are destined.
The serpent's bite on the genitals of Minos (da Cesena) illustrates Michelangelo's disdain for the Cardinal and of course Baigio must have been furious but.... A point well made I believe!