And if you look closely at these fibers
or the fiber orientation of the muscle, the fibers are going straight up and down... Welcome to the Anatomy Lab everyone! Today we're talking about six-pack abs
and why all of you can have a six pack. Now this is obviously going to be a
little bit different than your typical six-pack video because we're gonna
use cadavers to show this muscle. And more importantly talk about the layers
you have to go through to even visualize it at the gym, the beach, or more importantly
— during your personal flex-a-thons. And also two factors that you can
actually control with the six-pack. We'll address that. How this muscle functions and why
we choose certain types of exercises to make this thing stronger. So, let's do this! Saying that everyone can have a six-pack
is building from the foundation that everyone has the muscle that forms the
six-pack, called the Rectus Abdominis. Now I know — we're more concerned about seeing it, and you don't really consider somebody having
a six-pack unless you can see the muscle. But hey — we've all checked that first
box of at least having the muscle. But there's something about
the structural features of this muscle that makes
people all excited about it. So let's take a look at the cadaver
and go over some of those features. So you can see we're looking at an
anterior view of the abdominal wall. On the left side we've
exposed the Rectus Abdominis. Now I just want to mention why this
thing is called the Rectus Abdominis. "Rectus" means straight. And if you look closely at these fibers or the
fiber orientation of the muscle, the fibers are going straight up and down, and "Rectus" meaning
straight — "Abdominis" — pretty good name. Now the other feature that people love about
this muscle is that it's segmented into blocks, and that's why it gets nicknamed the six-pack,
but most people actually have eight blocks. And if you take a look we have these little
intersections here, and these are truly called Tendinous Intersections,
or Tendinous Inscriptions. And again, most people have
three intersections here. But what that does is creates one, two, three, and four different blocks
that make up the Rectus Abdominis. One other thing that's interesting
about those Tendinous Intersections, is they vary as far as how they
look or how they're oriented. Some of them have more of a slanting
orientation or oblique orientation. Some can be more straight across, but
again that varies from person to person. Now those are the typical features that we get all
excited about when we see the Rectus Abdominis. But how many layers do we have
to go through to see this thing? On the cadaver here you could see that we
exposed it on the left but on the right there was this white connective tissue that we
removed in order to see it on the left side. This white connective tissue is
referred to as the Rectus Sheath. And this Rectus Sheath is pretty awesome! This Rectus Sheath is related to
the muscles on the sides, here. Now, if you're concerned about the Rectus
Abdominis in the six-pack, you've probably thought about the obliques or worked out
the obliques at some point in your life. And those are the muscles
on the lateral body wall. Now those are sheet-like muscles too, and the muscle fibers end about
where the Rectus Abdominis starts. Again on the cadaver, this is about
where your obliques would end. You can't see them very clearly because we haven't
finished the dissection on the lateral side here, but this is about where they would end. That's the muscle or the "meaty part". But they have a sheet-like tendon that
continues over the Rectus Abdominis, and that's what this Rectus Sheath is. This is a continuation of the tendon of
the obliques and the Transversus Abdominis. And what's really cool is, you got
to think about it coming from both sides — that sheet comes over and covers the
Rectus Abdominis ,and it meets in the middle. And where it meets in the middle,
it creates this straight up and down band, which is another structural feature
we love about the Rectus Abdominis. This band is called the Linea Alba. Let me show you on the cadaver here. This is that central line that you see
on people with the six-pack muscle. And this comes up and down vertically,
and it's just the connection of the Rectus Sheath from the right, and the
Rectus Sheath from the left, which again, is the tendons of those lateral body wall
muscles, and it attaches in the middle here. Now a little bit of an FYI
in this particular cadaver, this Rectus — or I'm sorry —
this Linea Alba but by the way, Linea Alba just literally translates to —
"Linea" means "line", "Alba" means "white". But this one is expanded. And this is actually when it
gets pulled apart too far, and called Rectus Diastasis, or Diastasis Recti. And that's just essentially when the Rectus
Abdominis muscle pulls a little bit too far away. This can happen from a build-up
of body fat underneath. It can also happen to women
a lot during pregnancy. We actually talk a little bit about this in
our hernia video if you want to check that out. But only after you finish this one. So a quick checkpoint — yes, all of us
have the muscle that forms the six-pack called the Rectus Abdominis and all of its
cool features that we all geek out about. And then we saw the first layer covering
it up called that Rectus Sheath here. Now that is one layer we have to consider about,
"seeing" through in order to see this muscle. But there are still three other
layers on top of the Rectus Sheath that influence how well we can see the six-pack. So in order to do that we're going
to use a different cadaver dissection to illustrate those different layers. So, to the other cadaver! So what are these other layers that we have to
go through in order to see the six-pack muscle? Now as I mentioned earlier, we came over here
for a reason — to show a cool dissection. So let's orient you to this
dissection that we nicknamed our chest plate dissection, because of
the anterior thoracic or chest wall. You can see the Sternum here. We've got the ribs, and even continuing down to the anterior or the front
of the abdominal wall here. Here we've exposed two of the blocks of the
six-pack, or the Rectus Abdominis muscle. On the left side we've got the Rectus Sheath fully
covering the six-pack muscle in all of its glory. And even on the right side we're
covering up the superior aspect of this Rectus Abdominis, or
again the six-pack muscle. Now one quick thing I just have to address here
— we did not keep the belly button to be creepy. This is for a frame of reference
and — why we're here — to show you the layers we have to go through in
order to see the Rectus Abdominis. So the first layer we're going to
address is the top layer of the skin that we call the Epidermis — obviously
the most superficial layer of the body. Or in this case, the skin. The next layer down is the Dermis here, but if I pinch here I'm pinching
both the Epidermis and the Dermis. The majority of that tissue that I'm holding
in the probe there is the dermal tissue though. Then we move on to the third layer down which is the Hypodermis, also known
as the Subcutaneous Tissue. Now this is made of adipose tissue,
which is a fancy-pants name for fatty tissue, which is going to come
back in our discussion in just a second. We have to go to layer 4, which we
already have met before, but that's the Rectus Sheath here, underneath the Hypodermis. So think about that. The muscle is the fifth layer down. We have to go through four layers
before we can even see this muscle. The Epidermis, the Dermis, the Hypodermis — also
Subcutaneous Tissue — and then the Rectus Sheath. Now earlier I mentioned there were two
variables that we had control over. So that means there's three things that we have no control over when we're talking
about this five-layer plan. And let me go a little bit
more into detail with that. The Epidermis and the Dermis — we're not going to change the thickness of that —
we have no influence over that. If we go down to where the Hypodermis is, yeah
— we're going to have some discussion about our control over this layer. The fourth layer down, which is the
Rectus Sheath — again no control over. But then when we get down to
the Rectus Abdominis — can we control how big or how robust that muscle is? Absolutely! So let's start with that Hypodermis
and the control we have over that. You can see here it's about
about a half inch thick, but it can obviously be thinner in really slender
— or you could say like the body builders. Or even up to inches thick in certain individuals. But everybody wants to know how thick or what body fat percentage do you have to be
at in order to see the six-pack. People want this magic number of like, "you can see the six-pack guaranteed at
15.299999% of body fat or at 10.35%." But this is not how it works because
there are some variables with body fat percentage from individual to individual. What I mean by that is not everybody pulls fat from the same area
exactly when you lose body fat percentage. It's not like you can squeeze everything....
"just take it from my abdominal wall when I'm losing weight, not from my butt
or my hips or anywhere like that!" Based on genetics and even gender
there's some differences on where your body might preferentially pull fat from. Now some people might say, "you know...
if you're working your six-pack muscle, that's going to tell your body
to pull fat from that area..." And there's just not enough concrete
evidence to make that claim. Again it just comes down to, eventually
as the body fat percentage goes lower you're going to see certain muscles
better and eventually the six-pack. So even though nobody can give you
an exact percentage of body fat to see the six-pack muscle, I can
give you some generalizations. Six-packs can shine through a little bit or at
least kind of squeak through to see the light in the mid-teens. Now you'll be I'm sure shocked to know that
there's also some variables that influence that, but that is the other variable that you can
potentially control with how robust this muscle, the Rectus Abdominis is,
based on your workout routine. So what I mean by that — if the muscle is a
little bigger, a little more robust, it's likely to shine through or be a little bit more visible
or easier to see at a little bit more of a higher body fat percentage than say if the muscle was
all wimpy and flaccid and just not very strong. And frankly, just never worked out. So again, because I love to review
things... control what you can control. How robust the muscle is, and
how thick the Hypodermis is. But going back to how robust the muscle
is, we should talk about what this thing can do and why people choose certain
exercise routines to work this muscle out. So why people choose certain
exercises to work the Rectus Abdominis is based upon the muscle's function. Now that may sound kind of obvious, however
there's still confusion sometimes on how this muscle exactly works and
what exercises I should choose, and can I choose exercises that maybe target
the upper Rectus versus the lower Rectus. So to alleviate that confusion, we're
going to go over some of the details of what this muscle is designed to do
and how it mobilizes the skeleton. And we have Geoffrey to help us with
this, as well as my rubber band. So we're going to use this rubber band
to represent the fiber orientation of the Rectus Abdominis on Geoffrey. Now of importance here is this
idea that most skeletal muscles attach from one point of the skeleton to another. And when the muscle contracts it pulls
those two points closer together. So let's look at those points on Geoffrey here. If you look at his rib cage here you can
see some blue markings that we've put on on the ribs here and then also a
blue marking on the Xiphoid Process. These are attachment sites
for the Rectus Abdominis. The superior aspect or the
upper aspect of the rectus. For you anatomy geeks, these attachment
sites represent the insertion of the muscle. Now the other attachment is down on
the pubic bone or the pelvis here. Which again for you anatomy
geeks, this is the origin. Now for those who haven't
taken anatomy before origin and insertions they're both attachment sites. The insertion attachment site is
typically the more mobile — typically. We can change that sometimes. The origin which was down here on Geoffrey
is typically the more fixed point. When we talk about pulling
point A closer to point B. So let's do this with the rubber band. You can see coming down, like so. This would be the fiber orientation
of the Rectus Abdominis. Now I want you to think about this, as far as, "if this rubber band were to
get shorter, what would happen?" Now if I pull it on to me in that same
orientation here, from point A to point B, typically when this Rectus Abdominis — imagine
I'm on the floor though you guys, with my back on the floor — if this were to contract it
would pull me in this direction, like so. You can see on my rib cage, this attachment
got pulled closer to the lower attachment of my pelvis or my pubic bone, and causing
what we call flexion of the lumbar spine. So as the Rectus Abdominis contracts, it
mobilizes the lumbar spine or flexes it. So if you were to open up an anatomy book
and go to Rectus Abdominis and look at its function, it would — crazy —
say flexion of the lumbar spine. So how do we apply that knowledge of
the function of the Rectus Abdominis to say like selecting exercises or
workout routines to work this muscle? Now to be clear the purpose
of this video is to not give you every single exercise that you
could do or these specific routines. We're going to leave that to other
YouTube channels like Athlean-X. We'll put some cool links in the description
to some really effective ab routines. But our purpose is to give you this idea, or
give you some concepts to look for in all of your ab routines to get this balanced approach
to working the whole length of the muscle. Earlier I alluded to this idea of, "can we
work the upper Rectus versus the lower Rectus?" And yes — there's some truth to that. Although I do think it gets
blown out of proportion and there's some misleading information out there. Almost as if the upper Rectus is a completely
separate muscle from the lower Rectus. Clearly from our cadaver dissections
we know that's not the case. But we can target certain areas
of the muscle more so than others. Let me give you some examples of this. The two examples I want to give you,
mobilize the skeleton differently, yet are still contracting the Rectus Abdominis. The first one is the good
old-fashioned abdominal crunch. When you do an abdominal crunch,
your pelvis is fixed to the ground and when you contract the six-pack muscle
it pulls the ribcage closer to the pelvis. Now, if you compare that to another example
of an exercise, let's say we want to fix our rib cage to the ground and then
pull our pelvis or roll our butt up off the ground and kind of roll towards
the pelvis like a reverse crunch. So you're essentially mobilizing
different parts of the skeleton with those two different exercises. Now the benefit comes from challenging
the muscle at multiple joint angles by mobilizing different aspects of the
skeleton or those different attachment sites which would help create balance
throughout the entirety of the muscle. Now again, don't get me wrong, either one of those exercises will fire
throughout the entirety of the Rectus. However the movements that tend to mobilize
the rib cage and pull it closer to the pelvis fire a little bit more into the upper Rectus,
whereas the movements that mobilize the pelvis and pull towards the rib cage tend
to fire more into the lower Rectus. So incorporating both of those
types of movements into your overall ab routine will create more
of a balance throughout that muscle. And the last thing I have to say is
to continually challenge yourself. That may sound kind of obvious,
however you want to continually to progressively overload this muscle
and continue to stimulate growth. Because if this muscle gets a little bit bigger
— what we call hypertrophy — it may shine through at a little bit higher body fat percentage
than it would if it were a little bit smaller. And then you can also continue
to work on that shrinking of the Hypodermis to make it even
more robust and glorious while you're frolicking on the beach or doing your
personal flexathon in the mirror by yourself. Thanks for watching and sticking around to the
end of our Rectus Abdominis video everyone so you could watch me do a shameless plug about
liking, subscribing, and leaving comments below, as well as turning on notifications
so you know when we drop new videos. And until next time have fun working
that wonderful six-pack muscle!
