So here I am sitting in a holiday house by the seaside, my kids are (finally) asleep, my wife is back home, and it's raining and cold outside. To make matters worse the wifi here is terrible, and netflix is completely out of the question. So what is a neuroradiologist going to do?
Well I have been thinking of creating neuroanatomy content aimed at taking folk from knowing nothing to, well, knowing enough (more on this at a later date) so I mixed myself a martini (Hendrick's, dry, twist) and started at the start. Lobes. Simple right?
So here is the question I immediately faced: how many lobes are there?
We all agree on the 4 of them.
- frontal lobe
- parietal lobe
- occipital lobe
- temporal lobe
Easy... so lets record the video right? Wrong. What about the insula? What about the cingulate gyrus and hippocampus? I've been playing this game a while, and really I feel I should know, or at least have an opinion, but the truth is it turns out this is fairly contentious stuff, maybe enough for a neuroanatomist to throw a punch after a couple of beers (or martinis).
One source I found begins with "The insula is the fifth lobe of the brain and it is the least known" which begs the question "what about the limbic lobe?" Is the limbic lobe the sixth lobe and so little know the authors of the above manuscript didn't know about it? (yes I know I am probably using the term "beg the question" incorrectly; pedant). You see the term limbic lobe has been around since 1850's when Paul Broca, no less, coined the term.
So I turned to Google's Ngram viewer for the answer:
And more specifically just the "limbic lobe" and "insular lobe":
Other than all the lobes taking a hit during the great depression and WWII, it looks like we can relatively safely ignore the 'limbic lobe' from this perspective, which is sort of a shame really.
When pitting the terms against their main rivals ("limbic lobe" vs "limbic system" and "insular lobe" vs "insular cortex") we don't really see a real contest either.
Anyway, enough of this silliness. Four lobes it is. Plus insular cortex. Plus cingulate gyrus (which since it spans both frontal and parietal lobes, I'm going to continue to think of separate). Time for bed.