The nine central scenes

Running down the centre of the ceiling, in narrative order, Genesis unfolds: the Separation of Light from Darkness, the Creation of the Sun, Moon and Plants, the Separation of Land from Water, the Creation of Adam, the Creation of Eve, the Fall and Expulsion from Eden, the Sacrifice of Noah, the Flood, and the Drunkenness of Noah.

Prophets, sibyls and ignudi

Around the Genesis scenes, Michelangelo painted alternating prophets and sibyls (female prophetic figures from classical mythology), plus twenty athletic nude youths — the ignudi — that showcase his sculptor's understanding of the human body.

Did he really paint it lying down?

No — that's a popular myth. Michelangelo designed a custom scaffold that let him stand while painting overhead, though craning his neck upward for years still took a well-documented physical toll, described in his own letters and poems from the period.