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I have extracted this (and other) nerves from cadavers, and this circuitous cranial nerve (XII?) is as beautiful and complex as the multibranch plexus-es (e.g. brachial). So delicate.
Human anatomy, at first glance, often seems wrongly-engineered. After you've worked inside dozens of people, you begin to realize that everybody is unique — and nobody is "textbook" anatomy. Who knows what all this goop even does?!
If you ever get the chance, I highly recommend this humbling human experience. My hope is that my own cadaver is ripped apart by somebody as crazy/appreciative as me =D
It’s interesting you mention
“Nobody is textbook anatomy”
I know you’re exaggerating for poetic effect but this might actually be true in some parts of the human anatomy.
For example the description of the anatomy of vessels and anastomoses around the knee…I have had a professor tell me that the standard anatomical descriptions for this might all essentially be fiction. Basically the variation in some of these vessels over there is so high that the standard anatomical textbook description might be wrong.
That being said maybe the professor was wrong. I don’t know. But it was an interesting thing to think about.
No, really: nobody has completely textbook anatomy.
Think of it like those blended-face photos. Anatomy books describe that.
I was being prepped for wrist/arm surgery years back and the anesthesiologist got a bit flummoxed and muttere, “huh, that’s strange… let’s get an ultrasound” while trying to administer a nerve block on my arm. I asked what and they ”oh, it’s nothing to worry about, but your nerve isn’t where it is supposed to be…”, and then knocked me out before I could ask anything else.
That’s why we use ultrasound on practically every block we do today.
For perspective, when I learned to do nerve blocks (UCLA Department of Anesthesiology, 1977-1980 residency), portable ultrasound for guidance was a pipe dream.
For the axillary approach to brachial plexus blocks, we tried to elicit paresthesias from actual needle impaction on nerves and then pulled back a tad and injected a bolus of anesthetic.
We did that repeatedly, aiming to deposit anesthetic near each branch of the plexus.
Failing that, hitting the brachial artery with the needle and then continuing to advance the needle until no blood could be aspirated, injecting half the intended volume of anesthetic (2% lidocaine with epinephrine 1:1000) behind the vessel, then withdrawing the needle until no blood could be aspirated and then depositing the remainder of the anesthetic on the front side of the artery was the technique of choice.
Diff'rent strokes.
Surprised to find a bunch of anesthesiologists hanging around here. How come?
HN is my favorite place on the internet. I only wish I'd discovered it before I stumbled on it in 2016.
Would you consider investing in becoming an imaging technologist in today's US healthcare market?
IIRC, ultrasound is top of that payscale..?
I honestly don’t know anything about that market. We don’t use sonographers because it’s interventional; I need to be able to control my own view very tightly.
Nuclear Medicine Technologists earn more.
Is ultra sound that little monitor they/you look at while the needle thing is in your arm to apply the nerve block? That process a bit unnerving no pun intended. I thought maybe since my arm had been tweaked by being in a full arm cast for a month even with the screen they weren’t going to find it.
Some people wonder why the use of ‘AI’ in pathology is not more effective, and this is part of the reason.
It seems like exactly the kind of thing AI will be better at than humans. If just needs to be trained on the variations instead of the textbook.
My thought is the exact opposite. AI can handle predictable situations fine, but the 20% of situations which are unpredictable require a general intelligence that can understand context that current AI technology (or possibly any AI technology) just doesn’t possess. There will always be situations that training doesn’t cover.
The other side is that AI can learn every last bit of information from all CT scans, operating room video recordings (and more) in the world with no rest or sleep, and with 100% diligence
But our current "AI" isn't Intelligent and it doesn't learn.
Sounds similar to symbolic reasoning (for example algebra) vs finding the most likely completion.
Hmm that is the opposite what I would have expected. Because there is so much variation an AI that has trained on an insane breadth of data should easily be able to outcompete a human on specialized tasks.
Unless that training on exceptions isn't quite enough to convey the principles needed to reason about the domain.
I am sure for some problems it will amaze and for some it will not.
Gradients, spectrums, distributions; oh my
Gradients, spectrums and distributions describe the quantifiable diversity in humans. People have different heights, weights, eye colors, and other numerically measurable qualities. We’re exposed to this and it’s not surprising.
What this thread is talking about is things like extra fingers, missing or extra nerves and muscles, and varying structural differences.
I recently started learning a lot about the muscular and nervous system in the hip area. Even on Wikipedia you routinely read things like „this muscles is missing in x% of population”. It blew my mind that there is so much difference to our internal structure.
The genetic code is basically configuring a generic vertebrate body; the same sort of variation we see between vertebrate species we can also see as developmental variation in a species.
"The average man doesn't exist."
-United States Air Force
The median man does.
and he is quite strange
I had an ingrown toenail fixed. There is a nerve that comes in and branches in two in the bug toe. In my toe it branches into three!
Even identical males twins don't have the same penis structure/routing. Thanks for sharing your own personal example (I am the twin, in mine).
Another example is that of sciatia, which is much more prevalent when your sciatic nerve takes one particular path to get through the glutes. Other routed methods and sciatia is much less likely to be debilitating.
So that's the reason behind the dick pics. I thought it was just to show off, but it's for identification. Makes total sense now.
It was a close run thing between that and retina scans for the top secret lab's security.
“Please insert identification token”
ValueError: Not enough values to unpack
A form of biometric authentication, perhaps? Assume one has a spare CT scanner or some such thing, and doesn't mind discriminating against roughly half of the population.
The Leftovers [1], season 3 episode 7.
[1] https://en.wikipedia.org/wiki/The_Leftovers_(TV_series)
Maybe NSFW. [1]
[1] https://www.youtube.com/watch?v=0zu4XlM_89s
I know someone where the main artery into one kidney branches in two. Seems like a possible evolutionary step to bifurcation into more smaller kidneys. ;-)
Anecdata: A family member had one of those third smaller kidneys.
I have that. One normal kidney on one side and two touching but distinct maybe 75% sized kidneys on the other.
How does one get this chance?
I watched a fullautopsy in a theater high school at the Walter Reed National Military, followed by an open heart surgery. I'm sure there are videos of this. Beware it's a lot they pick apart the human body.
The chest opener is one of the scarier physical tools within surgery... "ca-RACK-k-k-k-KK"
Multiple options, including: attend medical school; become employed by an anatomy farm.
As for "chance of being hacked apart," anybody can donate their cadaver to science — most facilities require prior enrollment and will recover the corpse, nationwide.
You might end up sold into scientific experimentation... if you're morbidly obese (e.g.) you won't be used for student anatomy (if you care).
And one example of scientific experiment is being left out on an open field to study how cadavers decompose when exposed to “the elements” wind/rain/sun/bugs/birds/wolves etc to help solve crime scenes. You can look up forensic anthropologists and body farms for more info.
Not my cup of tea, personally, but my ultimate point is you might get used in something you disagree with. Look into the history of cell lines used in medicine for some of the controversy and perpetual pain for surviving family members, as an example.
You may be able to find a local community college course that offers free/cheap observation or participation in human cadaver dissection.
This 2022 LessWrong post mentions a $60 5-hour option at the Sf Bay Area's Merritt College (in Oakland):
https://www.lesswrong.com/posts/5PBWgHiCiiJHjPRSn/what-it-s-...
This reminds me of a conversation I was having recently about genetically engineering humans. I think people are greatly underestimating the complexity of the human body and it’s nature mechanisms of adaptation. Everyone is a little different - but that’s okay because all the little feedback loops and receptor sites account for changes. Like a drug addict needing more and more to get their fix. There isn’t just one variable we can adjust to really solve most problems. You have to look at the entire web of interconnected systems and modulate how each of them work together. We sort of take it all for granted since life is so abundant, but it’s truly nothing short of miraculous.
Though arguably this should also make it easier to make changes, because the body already has to cope with so much natural variation.
But then you fix the problem at the wrong control-loop level and after a while it goes right back to how it was.
Also one substance can be used in multiple feedback loops in different tissues. Tweaking one loop without touching others will take some finesse.
Here by the grace of god(s)...
The brain is but just one part of an incredibly complex machination.
I know med students get to attend cadaver vivisections, is this accessible to others as well? (of course this may depend on jurisdiction and university practice, just asking in general in case anyone has experience).
Dissections, man! Yikes
Got grizzly there pretty quick
Probably only for some kind of research study.
Nervus vagus is X - the tenth cranial nerve
And it was originally the last cranial nerve in vertebrates, before the first spinal nerves have been incorporated in the cranium as the nerves XI and XII.
It and several of the nerves preceding it, which originally innervated the branchial arches, remain different in nature from the following nerves (spinal nerves + cranial nerves XI and XII), whose original main purpose was to innervate the somatic muscles. This difference is more important than whether the nerves happen to exit the central nervous systems between adjacent vertebrae or by holes through the cranium (which are the result of the first vertebrae becoming fused to the occipital bone).
The nervus vagus and its associated ganglia of the vertebrates has a correspondent in the nervous system of most animals, including the arthropods, as a vegetative nervous system of the gastro-intestinal tract, which is connected to the central nervous system from the head, e.g. with the tritocerebrum of the arthropods.
This is why I like HN
Thank you, I needed a consult on that one (but now cannot edit/correct it):
You are correct, Vagus is TENTH Cranial Nerve.
Not as good as doing your own dissection, but a million times better than an anatomy book is visiting a plastination exhibit:
https://breckyunits.com/ketoneMap.html
I attended the Bodies Exhibit c. 2007/8, which was a bunch of deceased Chinese prisoners preserved without consent... but it was still really cool.
Models of circulatory systems with plastesizers and then all other flesh removed — incredible and complex and unique-to-each-human.
2008/9 I did anatomy prosections and had an absolute blast, but ultimately did not become licensed.
Yes, a bit uncomfortable to consider the ones they have plasticized into sexual acts into eternity and the pregnant woman and fetus (and there’s a lot of intrigue into that poor lady and baby). But ultimately, the non-consensual advancement of understanding of our bodies is a deep, dark, tragic rabbit hole that goes from antiquity up to… this very moment.
Don’t know what to do with the information I have discovered in the end but a good reminder to pause and reflect occasionally with the hope that we may not enable whatever the next “great idea, damn the costs” is.
Hold on. That's the "Body Worlds" you are referring to?
https://meded.ucsf.edu/willed-body-program :)
For Texans, UNT has both a medical school and an anatomy farm.
https://www.unthsc.edu/center-for-anatomical-sciences/willed...
I had a blast.
And I think with "most of the cells in your body are not you" and gut biomes and more...
I think everyone is their own ecosystem too.
cranial nerve X: https://en.wikipedia.org/wiki/Vagus_nerve
One of the most incredible exhibits I've seen are the anatomical tables on display in the Royal College of Physicians museum in London. When I walked into the room there were these 3-4 "doors" with what looked like shadows of people on them. The more I looked, and the more I understood what I was looking at, the more amazed I became.
The museum, and building I think, was closed for a few years but understand it's back open again.
https://history.rcplondon.ac.uk/collections/art-and-objects/...
The tables are visually spectacular. They show the recognisable form of the human body laid out flat, as if illustrating a book. The nerves, veins and arteries on display were dissected at the University of Padua’s famous anatomy theatre in the 17th century, and skilfully arranged on varnished wooden panels.