What's the reason behind St. Thomas Aquinas word choice "angelicus" in the hymn "Panis angelicus"?

If the hymn [*Panis angelicus*](https://en.wikipedia.org/wiki/Panis_angelicus) refer to the Eucharist (flesh of Christ, bread of life), why did St. Thomas Aquinas not say "Christ's bread" (*Panis Christi*, if that's the right Latin grammar) instead of "Angelic bread" (*Panis angelicus*)? Why switch the focus from Christ's body to Angels?