Haha, yes, it its Greek mythology-- and the pose IS reminiscent of The Creation of Adam -- an iconic pose, for sure.
In any case, the myth in question is that of Endymion and the moon goddess, Selene. She loved how he looked sleeping in a cave and was afraid for his eventual death due to his mortality, she so asked Zeus to put him in an eternal slumber so she could always visit him in his dreams. His existence was compromised by this, and as such the depiction is him in a state of agony.