What do we have here?
Oh, merely a close-up from Alberto Sotio's 1187 crucifix "Christus Triumphans" in which the skull of primordial Adam drinks sacrificial blood from the pierced feet of Jesus on the hill of Golgotha.
With imagery such as this, is it any wonder the Western world is so preoccupied with vampires? Blood becomes a drink of cosmic salvation and immortality, rather than the nutrient-poor diet of parasites.
As discussed on Key to Umbria, the full Christ is pictured with his eyes open, seemingly impervious to his physical torments. This was the predominant style prior to the 13th century, during which it became increasingly proper to depict the suffering of Christ (Here's an extreme of that).
He looks so detached, so otherworldly...