Are YOU Missing a Muscle??? | Here's a Test to Find Out!!

... but it also flares into the palm, or  this palmar aponeurosis — which I'm going   to zoom in for you — that you can see  in the palmar surface of the hand here. Some of you are losing muscles! And I'm not talking about because you're  sitting on your Gluteus Maximus all day long,   watching amazing anatomy videos on YouTube. I'm talking about that you  were never even born with them! There are a handful of muscles in the human  body that are variable from person to person   because these are thought to  be evolving out of humans. We need to talk about why that is,   and we're gonna even talk about a little test you  can do to see if you've got one in your forearm. And don't worry — if you don't have this muscle,   you can just tell your friends that do that  you're a little bit more evolved than them. So let's do this! As I already mentioned, there are  a handful of muscles in the human   body that are variable from person to person. And we're going to focus on this one in the  forearm because you can actually figure out if   you have this just sitting here watching this  video with a little test that we'll show you. The other ones, you're gonna have to do  some sort of imaging study to find out   if you have those, and that's just  not really feasible for most of us. But to understand how this works with  this forearm, let's take a look at the   upper limb dissection to get some context  around the muscles of the upper limb. So here is a dissection of the upper limb. Just FYI you guys — people get a little  bit uncomfortable with fingertips and the   skin of the fingertips, so we've just covered that   for your viewing pleasure — or your  viewing comfort, I guess I should say. But let me move the upper limb  so you can orient yourselves. It's essentially just like my  upper limb is sitting like so. Now this is the brachium, or the upper arm,   which there are 4 total muscles here  in the brachium, or the upper arm. Now if I move down here and grab the forearm  — which the fancy-pants name for forearm in   anatomy is the antebrachium  — there are 20 muscles here. So 4-20. Some of you remember 420 for  certain extracurricular activities. I remember 420 because of its  reference to anatomical awesomeness. So regardless of how you want to  remember the reference of 420,   let's just go a little bit further. So again, 4 muscles here, 20 muscles here. But there are 11 more inside the hand. And if we take a step back and kind of think  of that logic — the muscles of the brachium,   or the upper arm, are going to mobilize the elbow. And what does the elbow do? We're like flexion, extension, and we're kind of  done with also some supination, and that's it. But when we get to the forearm  muscles and the hand muscles,   we're doing all sorts of things like,  you know, abduction and adduction. Waving, things like this... wiggling  those fingers... doing "the Spock"...   you know, opposition — things of that nature. Lots of specialized work here. So again, it would make sense to have more muscles   for more, you know, fine motor movements that  we're going to do with the wrist and the hand. Now 20 muscles here, right? Some of you only have 19.... And finally, we can talk about  this mystery variable muscle here. So let's take a look here at  the cadaver again, and here is   this mystery muscle, called the Palmaris Longus. Now you can see why I got the name Longus,  because it's a fairly long tendon here. There is a Palmaris Brevis, FYI. But it also flares into the palm, or this  Palmar Aponeurosis — which I'm going to   zoom in for you — that you can see in  the palmar surface of the hand here. Now again, this muscle coming all the  way back to the elbow is not a very big   muscle here — just a small little muscle  belly, so not a very powerful muscle. But what does it do? This Palmaris Longus muscle  can weakly help flex the wrist. I say weakly, because there are other  muscles that are much more powerful   and stronger with flexing the wrist. Now because it goes to the palm of the hand and  that Palmar Aponeurosis, when you do certain   gripping motions it can put tension on the skin  and the connective tissues of the palm to kind   of help create that cup in the palm of your  hand that you're seeing here with gripping. So this always comes back to this question of,   "why do some people have this muscle  and others not have the muscle?" And those who don't have these variable muscles  that we've mentioned, don't really miss them. And what I mean by that is  that they're not necessary   for day to day functions or physical activities. For this muscle in particular — remember  we had 11 other muscles in the hand   and all these other forearm muscles  that could perform similar functions. So if you don't have this muscle, you  can still do all the hand and wrist   movements that you would need to do even  without the small little Palmaris Longus. And of course, this knocks  on the door of evolution. And to give this brief overview — or  this idea of how this works — is animals,   over the "bazillions" of years of development  and evolution and things of that nature,   they were exposed to certain environmental  factors and participated in certain activities,   and a combination of all these variables  activated and turned on certain genes. And as those genes were more active and  more frequently turned on and expressed,   those genes were more likely to be  passed on to offspring in generations. And as things got more specialized,   some muscles took over other functions  and rendered other muscles less useful. And that's the idea of this muscle   kind of evolving out of humans,  as well as the other muscles. And just one quick little thing I need to mention  before I show you the test to see if you have this   muscle — Justin and I have been posting on TikTok,  Instagram and YouTube for a little while now,   and we've noticed there are some  trigger words or trigger topics   that get people really fired  up in the comments section. Evolution tends to be one of those, you know? So whether you believe in evolution,  or have some religious convictions,   or a combination of the two — go ahead and  discuss, but just be nice to each other. It's not that hard! It's — you know, the Institute of Human  Anatomy comment section is a safe space, okay? And I'll even start — I believe in evolution  — obviously, because I'm teaching about this. I think the evidence is pretty strong. However, I grew up in a strongly religious  family, and i don't necessarily think they   have to go against each other —  they can coexist, in my opinion. Let me know what you think below. So finally, we get to test if  you've got this muscle or not. To do this, I must de-glove. Okay! So what you're going to do, is you're  going to slightly flex your wrist. You don't want to crank this thing all the way up. You just want to slightly give it some flexion,   and that's not going to give  you everything you need. What you need to do, is slightly flex the wrist,   and then pinch your pinky and your  thumb together pretty tightly. And you can see that difference of that tendon  that starts to bulge out of my skin there. Now don't get confused by the secondary  tendon that's next door to it,   as you can see there's two tendons here,  but it's the one that's bulging out more. The one that's closer to the thumb   is actually this other muscle right  here called the Flexor Carpi Radialis. If you want to get more information  on that, Justin just did a   Carpal Tunnel video on it, so fun there. But again, take a look at how that works. But I need to show you — my other side. So if you take a look here, I do not have it on my  left wrist or left forearm — it's missing there. I just have that other tendon,  that Flexor Carpi Radialis tendon,   but I'm missing the Palmaris Longus. And a lot of you will see that you'll  have it on one side versus the other...   you may have it on both sides...  or you may not have it at all! And again, like I mentioned  at the beginning of the video,   if somebody tries to make fun of you  for not having a Palmaris Longus,   your rebuttal is that you are a little  bit more highly evolved than them. My left side's a little confused compared  to my right side — it wanted to evolve   faster than my right side, I guess... who knows? And one cool thing, from a clinical perspective. For those who have this tendon you could use it   for a graft if you had some  injury to a certain ligament. For example, pitchers will sometimes injure —  pitchers like baseball pitchers — will sometimes   injure this ligament called  the Ulnar Collateral Ligament. And to help repair this ligament, you could  take this tendon from the Palmaris Longus   and use it as a graft to  repair this damaged ligament. So this wimpy little muscle can be used  for, you know, showing people cool tricks. But at the end of the day — eh... As always, thanks for watching  and going on this tour of the   upper limb and the Palmaris Longus with us. Please like, subscribe, ring the bell  so you know when we drop new videos. We love the comments everybody  — please blow that section up. We have our affiliates down below — we  love and appreciate all of your support. And have fun testing your Palmaris  Longus with your friends and family. I don't know what that was...  like spirit fingers... it has   nothing to do with Palmaris Longus... okay bye!

Channel: Institute of Human Anatomy

Views: 622,747

Rating: 4.9283366 out of 5

Keywords: missing muscle, am i missing a muscle, are humans losing muscles, palmaris longus, palmaris longus muscle test, palmaris longus muscle, palmaris longus test, palmaris longus action, palmaris longus palpation, palmaris longus function, palmaris longus muscle anatomy, human anatomy, human body, arm anatomy, real human body, anatomy, institute of human anatomy, ioha, muscle anatomy, forearm anatomy, evolution, evolution of arm, evolving muscles, are humans still evolving, forearm

Id: yc1VgVw7F9w

Length: 8min 43sec (523 seconds)

Published: Fri Mar 05 2021

Reddit Comments

[u/RandomDustBunny]

I honestly expected a wee bit more interest in this video. Not in terms of comments but assuming a certain correlation of post up votes as having seen said video.

Though he says missing a muscle or two wouldn't at all impede everyday function, armwrestling is not everyday and couldn't be further.

[u/Stoproll]

I'm missing this tendon in my L wrist, but have it in my right. In my opinion it actually makes a fairly significant difference interms of squeezing power, and somewhat of a difference on wrist flexion.