From my understanding, Yggdrasil from Norse mythology is basically a representation of the body, soul and chakras. Its been a long time since ive read about Norse mythology, so anyone can correct me if im wrong. Its supposedly the tree where all existence comes from, and the '9 worlds / realms' from Norse mythology is a part of this tree, as the tree formed the 9 worlds. The 9 worlds is basically symbolic for the 9 major chakras of the soul.
The tree could even be viewed as being just the element Ether all by itself, which is where existence itself comes from. Ether has all the five elements in it, and its where existence and consciousness forms from.
Im not sure how ether works, but I believe the elements causes vibrations in the universe, the vibrations create light, and from this light is where matter is formed, also the soul and consciousness, and the 'light body' and we all know the soul is made of light and the 5 elements.