As a visually oriented person, I need to protest. This is not important, other than it’s been driving me crazy.
I’m not sure when it happened, and definitely not why, but at some point the expression “getting my arms around a problem” inexplicably turned into “getting my head around a problem.”
Now really. The reason such visual metaphors exist is to enable you to picture an experience and thereby make it familiar. This one is only familiar to science fiction. Were it “getting my MIND around a problem, I’d say maybe. The mind is a large concept, not actually made out of, well, bones.
This head-around phrase pretty clearly demands that you imagine paired skull-lobes growing from either side of the forehead and slowly encircling the whatever-it-is, then performing a mind-meld or crushing it with powerful skull-lobe muscles. The phrase has gotten itself around my head.