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!