As you leave the Temple and begin crossing the bridge you'll come to some Hel's Bramble blocking the way forward with a Legendary Chest to the side of it. Look up at the ring overhead to find the first Raven.
Once your platform falls down and you fight the Hel-Viken in the side path to the Bridge Keeper, you'll have three ways to go. Climb the north wall and look at the rocks at the back to find this Raven.
On the same platform as before, look down to the ravine to the southeast to find another Raven circling around.
Return the Helheim with Atreus and proceed along the bridge until you come to the first Shatter Crystal. Shoot it to find a coffin and a Raven above it.
Heading further along the bridge you'll come across two more Shatter Crystals. Behind the third one you'll find the next Raven along with a Hidden Chamber entrance.
Head into the Hidden Chamber and take the elevator down before climbing the stairs. You'll find a coffin here and above it, the final Raven.