The brain is Ḥokhmah, it is inner thought. Binah is the heart, and with it the heart understands. And upon these two it is written: (Deut. 29:28) The hidden things are for Y”Y our God....
Higher Keter, it is the ‘crown of sovereignty’, and upon it is stated: (Is. 46:10) He tells the end from the beginning... And it is ‘the skull of phylacteries’ [Var. ‘the skull that does not lay phylacteries BT Rosh HaShanah 17a ]. Inside it is YOD QE VAV QE (=45), which is ‘the way of emanation’.
It is the watering of the tree, with its arms and its branches, [Var. and its faces] like water, which irrigates a tree, and it grows through that watering.