cranial trivia


Finally! The awesomest upper limb mnemonic is fit for print! So are the branching mnemonics, though they are less fun. I have also added one of my own devising to help me remember how all the bones/VANs/compartments relate in the forearm. Happy studying?

Real Therapists Drink Cold Beer

The brachial plexus gives rise to the set of nerves that supply the arm and forearm. I wish you could dissect it for yourself, because let me tell you, this thing is beautiful! The brachial plexus is as intricate as the cranial nerves are dizzying. Tracing its reticulations is fairly straightforward, but sometimes it is difficult to keep track of all the functional parts of a 3D network. That’s where real therapists help us out; each of these first letters stands for a successive functional portion of the network: Roots (C5-T1 ventral rami), Trunks (upper, middle, lower), Divisions (anterior/posterior), Cords (med., post., lat.), and Branches (godawful lots).

So, how does one address the godawful many branches? Behold:

LML (lateral cord): lat. pectoral nerve, musculocutaneous nerve, lateral root of the median nerve. Frankly, I prefer remembering it as LLaMa.
ULTRA ULNAR (posterior cord): upper subscapular, lower subscapular, thoracodorsal (nerve to latissimus dorsi), radial, axillary
M4U (medial cord): just in time for Valentine’s day, eh? Medial pectoral, medial cutaneous nerve of arm, medial cutaneous nerve of forearm, medial root of median nerve, ulnar

And all that stuff about compartments? Here’s how I began:
Um, Right or Left?

In anatomical position, the ulna is medial and the radius is lateral. Once you start pronating and all that good stuff, all bets are off, so know your stuff! 😉

Here’s take II. I’ll post more as I encounter socially acceptable ones (not that many of these :/).

Two Zebras Bit My Cookies – Your head is a complicated place. All nerves lead to the brain, just as all roads lead to Rome. Here, however, it looks more like traffic in New York City Boston. Among the zigzaggy roads is the facial nerve, which is responsible for all the muscles of facial expression. Although it also has some funky side-roads, there are 5 main branches fanning out across the face from somewhere just south of each ear: Temporal, Zygomatic, Buccal, Mandibular, and Cervical.

C3,4,5 Keeps the Diaphragm Alive – As amazing a place as the head is, it wouldn’t be much without the lungs. And the lungs, well, they kinda need the diaphragm to do their job. The diaphragm is the big trampoline of muscle under your ribcage that pulls air in (and pushes it back out, if you’re panting). It’s innervated by the phrenic nerve, which comes from cervical (neck) vertebrae C3, C4, and C5. This is right above where the nerves to your arms come out, which is why some quadriplegics can still breathe on their own. It’s also why neck injuries are so dangerous; cut this puppy and you stop breathing.

Just when I thought that med students couldn’t take a joke to save their lives (the immuno jokes come from a guy who swapped the clinic for the lab years ago), Dr. D introduced us to the rich tradition of mnemonics.

There are thousands of essential things to remember for clinical anatomy. It’s not just knowing the names of the bones or the muscles, but understanding the development, the interactions, the variations, and how it can all go wrong. Sometime later we’re supposed to learn how to put this Humpty Dumpty back together again. In the meantime, the mantra is simply “don’t kill the patient.” It helps that this is not a concern relevant to our first patient.

As we go through the process of cramming all of the information into our leaky skulls, it’s useful to have a few phrases handy to jog your memory. The older students and professors pass these down with great zeal and ceremony. I’d love to share them all with you, but all the best ones are extremely dirty. Here are a few of the more drab, socially acceptable examples:

  • C5,6,7 keeps the wings from going to heaven
    • The serratus anterior muscles are what keep your shoulder blades flat against your back. Without them, your shoulder blades would fan out like wings whenever you pushed on anything, hence the term “winged scapula.” It’s also responsible for the alarmingly rippled, triangular chest of the western superhero. Yeah, Batman! They’re innervated by the imaginatively titled “long thoracic nerve,” which arises from the 5th, 6th, and 7th cervical nerves. This is one of the few nerves that actually runs on top of the muscle, so it is very easily damaged. The moral of this story is: don’t get into a knife fight…unless you’re Batman. That armor’s better than kevlar.
  • I ate ten eggs at twelve
    • In order for you to breathe, you have to be able to manipulate the pressure in your lungs. Part of this is done with the muscles that run between your ribs, but most of the work is done by the diaphragm, a big muscle that seals the bottom of your ribcage. However, you can’t have a perfect seal; you still have to get food to your stomach and blood to the lower part of your body! To do this, 3 tubes have to pass through the diaphragm: the esophagus, the aorta (the major artery), and the inferior vena cava (the major vein). They do these at different points relative to the vertebrae, which are numbered. The IVC crosses at the spinal level T8. The esophagus goes through at T10, and the aorta goes through at T12.
    • As a bonus, this is how you get hiccups. The only one of those three structures that passes through the muscular part of the diaphragm is the esophagus (the IVC goes through the tendon, and the aorta kinda sneaks in behind everything, right along the spine). The contractions of the diaphragm and the contractions of your esophagus have to be coordinated so they don’t work at cross-purposes. When they get out of synch, you hiccup.
  • The poo-dendal*
    • I bet you can guess where the pudendal nerve is.

*This is actually a new one this year, courtesy of my friend Raven.

Accomplishments so far this week:

  • Correct conversational use of the word borborygm – the grumbling of the bowels
  • Ability to find a stranger’s aorta without cutting them open (note: it does help to introduce yourself first)
  • Identification of the tenderloin, which looks suspiciously like what you find in the grocery store.
  • Ability to make jokes about nitrous oxide and the SodaStream, thanks to a strange confluence of muscular physiology and Bed Bath & Beyond catalogs
  • Snickerdoodles

Also, good luck to my little buddies-by-association, Nate & Theo. Within a week of life, you have achieved the dream of my wannabe-cyborg generation. However, we would like you back. Don’t get too ahead of yourselves, there.

I’ve heard from several of you who have already managed to work the words from last lesson into daily conversation, even if it involved calling a certain professor a crump. Well done! Now, let’s step it up, shall we?

Kakistocracy – the rule of a society by its worst/least-qualified citizens. We had a good time with this word on Monday when combining a kidney dysregulation lecture with politics.

*Borborygm – keeping with the physiology theme, this is a medical term for a rumbling in the bowels. Sounds just like it, don’t you think?

*Gongfermor – a nightsoilman, dunnykin driver, or emptier of cesspits. By law, they were only allowed to operate at night, for *ahem* solid reasons. However, it was an industry at which you could make a decent amount of cash, provided that you didn’t mind the social ramifications.

Lumpkin – a clumsy blunderer, possibly a bit thick, besides.

Glabrous – smooth, free from hair or down. This could refer to the skin (a glabrous pate, perhaps? It amazes me that a word can feel shiny) or to leaves that don’t have any fuzz.

Remember, the stars are for extra credit! Let us all know of your triumphs. While I’ll be out of town for the next few days (celebrating the wedding of two of my friends with bowling, card games, and good times, then studying for two exams 8P ), I’ll get back to you guys next week.

Tomorrow marks our fourth medical exam this semester, this time in immunology. Naturally, this delicately balanced, devilishly complex field would be the one course in which we don’t have midterms; everything rests on the final examination. It’s infuriating, but logical when you consider that medical education now takes even fewer years than in the pre-genomic, pre-antibiotic, pre-molecular biological era. I think this is why our oath includes that clause about staying current in our field.

At any rate, I’m only griping because immunology is one of the coolest fields around, and is constantly changing. 20 lectures just can’t do it justice. Our professors do try to make the condensed material accessible, though, with quite entertaining results. So, for today’s study break, I thought I might share some of the explanations:

Concerning the differences between MHC Class I (how your cells present self molecules to the immune system) and MHC Class II (how special cells called Antigen Presenting Cells – or APCs – present extracellular molecules to the immune system):

  • It all boils down to Lindsay Lohan’s arrest record. Say you’re walking by a kindergarten, minding you own business,when you see a plastic baggie full of white powder sitting on the pavement. Now, if you’re incredibly naive, you pick the bag up and put it in your pocket, thinking that you’ll just throw it in the trash can down the street, but you forget. Congratulations! You are now an infected cell! Next day, a cop stops you for walking and chewing gum at the same time, and he makes you turn out your pockets. In there with your keys and your wallet and cell phone is the little white baggie. You say, “Gee, officer, that white bag isn’t mine, I just picked it up somewhere…” Guess how far that’s going to get you.
    Now, if you’d been an APC, you would have seen that bag on the pavement and immediately thought to yourself, Hmmm. I bet Lindsay Lohan’s been here. Don’t want any of these li’l tykes picking this up, so I’d better turn this in and get the cops to canvas the neighborhood. You double bag the suspicious evidence and flash your undercover MHC II license back at the station, so next time Lindsay shows her face, she’s toast. Case closed.
  • Of course, there’s more to MHC I and and MHC II than just where they get the peptides that they present. There are also different rules for how big the peptides can be. Think of it as New York versus San Francisco. MHC class II presents foreign peptides, and is a way of asking for help controlling a problem, so it’s pretty lenient. Pack a bunch a’ suspicious characters into a trolley car, let ’em dangle out the windows a bit, and then just shove ’em off towards Alcatraz. No worries. MHC I, on the other hand, tells the immune system whether you’re doing ok or have been infected by a virus, and the penalty for infection is death. Your cells are paranoid about what gets onto these things. It’s New York. It invented exact change. 8-10 amino acids or you don’t get on the bus.

Concerning immunoFAIL:

  • If the immune system worked perfectly all the time, we wouldn’t have doctors. Pathogens are pretty smart, too, especially HIV, which is able to hijack your helper-T cells and kill them to prevent activation of the killer-T cells, which could actually clear the infection. As we learned, the changes over time in this disease are kind of like replacing Eli Manning with Mark Sanchez.
  • HIV is a retrovirus, meaning that when it enters a cell, it back-transcribes itself into your very own genome. It’s pretty savvy, and has worked out that the best strategy is to build up a new army before busting out and invading more cells. So, it has to sequester a lot of its players inside the nucleus until it’s time for them to enter the cytoplasm. Think of the cytoplasm as an exclusive new club in the Seattle Space Needle. It has a fussy bouncer named Rev. Now, Bill Gates reaaaallly wants to get into this club, but as a young man his CRS nerd factor is just too high. He gets bounced like an olympic pingpong. However, a little later in life, he acquires RRE, which in this universe stands for gigantic piles of cash. This RRE bling is so thoroughly attractive that it outweighs the nerd factor, and the once disdainful Rev gloms onto Bill like a limpet and escorts him into the club for life.

And that, my friends, is how I will forever remember immunology.

P.S.

There are some more fun anecdotes, but my study break is up, so they’ll have to wait for later.

St. Paul's time

St. Paul’s time

This week I’m being treated to an unusual contortion of time. Normally it either flies or crawls, but now I have a fleeting period where the hours crawl by.  My labwork is on a 10-day wait step, and only two of my grad courses even meet this week, so there is plenty of time in the day (finally!) to rest up, get over my cold, and lounge on my sofa reading Girl Genius and eating cookies. Even mad scientists need some downtime, alright?

V&A time

Victoria & Albert
museum clock

It ends Friday with the introduction of Physiology to our course list. Then next week all experimental heck breaks loose. Then we add our first straight medical class and enter exams. Really, it’s just going to spiral from there into insanity.

What’s worse, I can already hear the ticking.

Before that, however, I have a tidbit for you in addition to the photos above, both of which are from London this summer. (Really, all I need out of my weekends is unlimited admittance to the Pergamon, V&A, and all those other fabulous museums.) I’ve now ventured into Manhattan for art supplies and have a few new pieces in the sketch phase, but for the moment I hope you enjoy revisiting these guys:

Sea's Revenge

Sea’s Revenge
(click for larger image)

Although I was finally able to hijack the library scanner for this, I no longer have editing software on my computer (yeah, yeah, I’ll go download gimp at some point). Apologies for the unmatted presentation here. It’ll get fixed eventually!

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