Hopefully this will be a fun new miniseries that will reoccur on my blog to teach you something new about your body. In a fun and interesting way of course (unlike the way I had to learn it ....just kidding, my professors are really great!) Plus, you wouldn't believe how much this education is costing me, might as well put it to some use already!
All of today's post will be related to the upper extremity (arm and shoulder) because that's the only thing I've been taught.
1. The tickle in your armpit is protecting something very, very important.
When you are tickled, your arm reflexes down immediately - this you should already know. But your arm is not just trying to protect that fat under that armpit (trust me, there's a LOT under there), it's also protecting this wonderful nerve bundle called "the brachial plexus." (AKA a fancy bundle of nerves that supply your arm, forearm, hand muscles and skin - all of it. Lose that plexus, and you basically lost an arm. )
Now, you typically don't lose the entire brachial plexus. But many people can injure it in a variety of scenarios (I've learned this from my exam questions) with knives and guns, falling out of trees, motorcycle accidents, somehow landing upside down right on your arm, etc. Or, if you pull a baby out by it's arm you could stretch and tear it.
As you can see, the plexus branches a lot right in the armpit, but it branches more after that, trust me.
( image taken from here )
2. Allen's test is really fun, try this one at home.
Basically... this test is making sure both sides of the arteries in your forearm make it to your hand (one on the ulnar side and one on the radial side). This could be important in case one is injured, so we know that the other artery will compensate!
Making a tight fist cuts off the circulation and the hand turns white, when I grab the two arteries and hold on to them his hand will stay white even after it's released from the fist. If I let one of the arteries go, his hand should fill with blood again and turn back to a dark pink. You can test both sides!
See for yourself: (it's only 15 seconds)
3. When your nerves of that brachial plexus get injured/compressed your hand is (obviously) going to react. Keep in mind it all depends on EXACTLY where the nerve is injured.
The symptoms are sometimes pretty distinctive here are some of them :
Ulnar nerve injury (claw):
(image from here)
Median nerve injury at the elbow (sign of benediction when making a fist):
(image from here)
Radial nerve damage :
(image from here)
4. So, dermatomes were something we were supposed to memorize for Saturday's exam. These are maps of the body that describe which spinal nerve innervates which area. They are useful if someone describes pain, odd feeling (paresthesia), or no feeling (anesthesia) in an area. But here's the catch, the nerves of the brachial plexus, described in number 1, are made up of little bits and pieces of different combinations of each of these spinal nerves. So if one spinal nerve is compressed or hurt due to an injury to the vertebrae, then you'll see weakness in those nerves.
Here's me studying those brachial plexus innervations:
The fun fact part is that when you get on all fours the dermatomes make sense!
5. No matter what anyone tells you, the best pneumonic for remembering the wrist (carpal) bones is the one from UNL's anatomy course:
"Some Lovers Try Positions That They Can't Handle"
Seriously, the one in our book is :
"Sandra Likes To Pat Tom's Two Cold Hands" (seriously what the heck)
Someone also told me this one just as awkward as the two above:
"Senior Lecturers Take Prostitutes To The Carlton Hotel" (really!!??)
(image from here)
Hope you all learned something today, have a fantastic week!
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