You can only view 3 videos without an account. Become a Member to access all videos on the website.
Muscles of the Trunk: Video #19 of Introduction to Functional Anatomy
Muscles of the Trunk (Video #19 of Introduction to Functional Anatomy) covers the muscles and their major locations that are found in the abdominal region and in the lower back. It will discuss key muscles, their shapes, sizes, and how they all interact to contribute to the trunk stability in various movements. It will also focus on the proper techniques for activating these muscles. Finally, it will discuss the common issues and injuries related to these muscles and how to address them so that your
Transcript
00:00:0500:00:10
We're going to go superficial to deep. So
00:00:0500:00:10
let's start with the external obliques.
00:00:1000:00:17
Now your external obliques fiber direction, which way does it go? This way
00:00:1700:00:23
right. The way your fingers would be if you put your hands in your front pockets.
00:00:2300:00:29
So you guys can write external obliques front pockets, to help you guys out a
00:00:2900:00:33
little bit. How many of you guys look at pictures of bodybuilders and fitness
00:00:3300:00:38
models, and you know you've seen a muscle and fitness magazine or a shape magazine,
00:00:3800:00:43
and people get all striated in here right, you see the lines. Which direction
00:00:4300:00:49
do those lines always go? Right because your external obliques are external
00:00:4900:00:53
right, they're the ones that are most superficial that's what we're seeing. So
00:00:5300:01:00
if the fiber direction is this way alright this muscle goes like this,
00:01:0000:01:09
what joint actions is it going to cause? Yeah which rotation is it? If this
00:01:0900:01:20
muscle shortens what's gonna happen to my spine? It's going to rotate this way?
00:01:2200:01:28
Alright if this muscle shortens it's going to twist me this way right, which
00:01:2800:01:37
would be contralateral rotation. So we got external obliques
00:01:4900:02:02
contralateral rotation, what else might they do? Okay so we got we got the
00:02:0200:02:05
obliquity thing, I told you guys muscles with a diagonal usually do
00:02:0500:02:09
rotation, we got rotation out. There's got to be a couple other things this muscle
00:02:0900:02:16
will do though. It's going to help with flexion right, because the obliques do lie in
00:02:1600:02:22
front of the lumbar spine right, this is the joint that they cross there in front
00:02:2200:02:34
of it. So external obliques flexors of the spine. I'm gonna say yeah. What else
00:02:3400:02:42
might they do? Lateral flexion. How many of you guys think lateral flexion? Yeah I
00:02:4200:02:45
mean how do people try to work their external obliques
00:02:4500:02:50
a.k.a their love handles, because they're trying to spot reduce the fat over their
00:02:5000:02:53
external obliques which absolutely doesn't work, and then they do an
00:02:5300:02:57
exercise which is kind of ridiculous we already talked about this yesterday. They
00:02:5700:03:02
do this one right we talked about this. Well your external obliques actually are
00:03:0200:03:05
not your primary lateral flexor of the spine,
00:03:0500:03:11
but do they lie lateral to the spine? Sure so they'll definitely help a little
00:03:1100:03:16
bit, it will definitely help.
00:03:2200:03:29
Now the other thing you have up on that chart there and this is more just some
00:03:2900:03:34
extra information for you guys, we were talking about connective tissue this
00:03:3400:03:38
morning right, when you open up a cadaver you don't see all these pretty red
00:03:3800:03:44
muscles, you see a lot of white connective tissue that is especially
00:03:4400:03:53
true in this area. The most superficial thing here on your six-pack is not your
00:03:5300:03:58
rectus abdominis, but this abdominal connective tissue. And
00:03:5800:04:02
you guys see a little evidence of that because what actually makes the 6-pack?
00:04:0200:04:08
You have the Linea Alba which is the connective tissue in the middle and
00:04:0800:04:13
then all of this these transverse little separations, which are also made of
00:04:1300:04:18
connective tissue. They're probably there because connective tissue with its
00:04:1800:04:25
rigidity and strength, probably improve the overall strength and ability for the
00:04:2500:04:30
rectus abdominus to prevent what? What don't we want to do with the lumbar
00:04:3000:04:37
spine? Forceful hyperextension right. So we have a nice nice bit of connective
00:04:3700:04:42
tissue here to help help the rectus abdominus to its job. Just reinforce it a
00:04:4200:04:45
bit. I think that's one of the next muscles up here, yeah rectus abdominus.
00:04:4500:04:52
This one should be pretty easy for you guys right. Rectus abdominus runs, which
00:04:5200:04:57
way does its fibers run? Up and down.
00:05:0300:05:08
So it runs up and down in front of the spine. What plane do you think it's
00:05:0800:05:13
probably going to work best in? It's a sagittal plane muscle, being that it's a
00:05:1300:05:17
sagittal plane muscle and it's in front of the spine, what do we think it's going to
00:05:1700:05:22
do as far as joint actions? Flexion. I
00:05:2700:05:33
always love every once in a while I get these calls from like a writer for like one of
00:05:3300:05:39
the magazines or whatever, and of course what do they always ask what's the best
00:05:3900:05:44
exercise for the abs. And of course what are they talking about when they say abs
00:05:4400:05:49
rectus abdominus, and my answer is always the same.
00:05:4900:05:58
What's the best exercise for the rectus abdominus? Flexion. Do you have anything
00:05:5800:06:07
other than flexion? No that's what the rectus abdominus does well. What else
00:06:0700:06:10
could the rectus abdominus do a little bit of? Does anybody know? Like think
00:06:1000:06:16
about your tilts, you remember your pelvic tilts right, it'll do this. Isn't
00:06:1600:06:19
this still spinal flexion though? Yeah you have to do spinal flexion to
00:06:1900:06:25
posteriorly tilt. So they'll be like so so the the rectus abdominus just is flexing?
00:06:2500:06:30
Yeah and it'll posterior tilt your pelvis. But what do you mean? Oh you can
00:06:3000:06:35
do a crunch, or you can do a reverse crunch.
00:06:3500:06:44
I guess isometrically you could do a plank. Would anything else really affect
00:06:4400:06:51
the rectus abdominus all that much? No. No the truth is when we look at EMG studies
00:06:5100:06:58
guess what has the highest activity for the rectus abdominus? Crunches, reverse
00:06:5800:07:03
crunches, like those things that actually do the action of really not that
00:07:0300:07:07
complicated right. What keeps most people from having a 6-pack, is it the
00:07:0700:07:13
exercise they chose? It's diet. How do you get a six-pack?
00:07:1300:07:19
Shut your face, move your glutes right.
00:07:2000:07:24
You want to get that tattooed, that was actually the original title of my first
00:07:2400:07:30
book, and the agents were like you can't have shut your face and move your ass as
00:07:3000:07:39
the title of your book, that's not going to work, and I was like why not. Internal obliques,
00:07:3900:07:44
internal obliques. So we talked about external obliques being this way right,
00:07:4400:07:49
those are the muscles you can see, it's fiber direction as if you put your hands
00:07:4900:07:55
in your front pockets. Guess which way the internal obliques go? This way all
00:07:5500:07:59
right. So it's like the direction your fingers would be if you put your hands
00:07:5900:08:04
in your back pockets. You guys cool with that.
00:08:1000:08:21
Internal obliques, so which way, what what joint actions are we looking at? Rotation.
00:08:2100:08:24
We got the obliquity, we know it's on a diagonal. We know it's probably going to
00:08:2400:08:28
contribute to rotation. You got to tell me ipsilateral or contralateral though.
00:08:2800:08:36
If it's this way and it's going to shorten, and you guys see how that would shorten.
00:08:3600:08:56
Exactly exactly ipsilateral, all right. What else might it do? Lateral, lateral
00:08:5600:09:00
flexion. Yeah it's on the side of the, it's on the side of the lumbar spine.
00:09:0000:09:12
I'll say lateral flexion. You guys think this can contribute to a sagittal plane
00:09:1200:09:18
motion, like you can contribute to flexion or extension.
00:09:2000:09:28
Flexion, why flexion? It's still in front of the lumbar spine right. Now remember
00:09:2800:09:33
your lumbar spine is way back here, so all these anterior core muscles that
00:09:3300:09:38
we spend so much, that we give so much attention right in the popular media,
00:09:3800:09:42
they're pretty much all flexors.
00:09:5000:09:53
Everybody's got this.
00:10:0600:10:10
So yeah so this does get a little confusing, the contralateral versus ipsi-
00:10:1000:10:16
lateral thing. So if you guys, let's pick two points right. These both, both these
00:10:1600:10:19
muscles have pretty broad origins, pretty broad insertions, but let's take
00:10:1900:10:25
the external obliques first, since we covered those first. Put one finger on
00:10:2500:10:34
your ASIS okay, and then put one finger back on your ribs all right. Now try to
00:10:3400:10:47
bring those two fingers closer. Which which direction did I rotate? I ended up
00:10:4700:10:53
rotating a little bit to the left right, so that's rotation to the opposite side.
00:10:5300:10:59
the muscle is on. Contra means against, right against our away, so that's
00:10:5900:11:04
contralateral rotation. Now let's do the same thing with the internal obliques.
00:11:0400:11:10
Let's pick a point, let's let's pick this little angle of your ribs here right, and
00:11:1000:11:16
all the sudden changes let's do that one. Point on your posterior ilium and now
00:11:1600:11:22
try to bring your fingers closer together. Yeah you guys see how that
00:11:2200:11:29
works. So now we have a muscle on the right is rotating me which direction? To
00:11:2900:11:34
the right. So that's the same side that would be ipsilateral. You want to totally
00:11:3400:11:42
freak yourselves out? When I rotate to the left, which oblique am i working?
00:11:4300:11:56
Oh yeah right external oblique right, but my left internal oblique. Muscles work
00:11:5600:11:59
best in the direction of their fibers. Isn't it kind of true that if I rotate
00:11:5900:12:06
this way, that this external oblique and this internal oblique kind of have the
00:12:0600:12:18
same fiber direction, and then if I go the other way its. Transverse abdominus,
00:12:1800:12:22
how many of you guys have heard of this muscle? Definitely a muscle a lot of
00:12:2200:12:30
people talk about. Definitely a muscle of a lot of controversy. But the transverse
00:12:3000:12:33
abdominus is an interesting one, because
00:12:3600:12:43
what joint action based on its fiber direction do you guys think this muscle
00:12:4300:12:46
does?
00:12:4900:12:57
Which is the fiber direction is is what? It's transverse right, that's why it's
00:12:5700:13:02
called the transverse abdominus because its fibers are orientated transversely. Its
00:13:0200:13:07
origin and insertion is basically the thoracolumbar fascia.
00:13:0800:13:11
It's a little different than that in textbooks but you guys get what I'm
00:13:1100:13:14
saying. The attachment goes from here, it
00:13:1400:13:19
wraps all the way around and goes right back into here. So when it contracts what
00:13:1900:13:29
actually happens? It's basically your weight belt right. You guys remember like,
00:13:2900:13:33
you guys seen the big guys with like the, and they do, they have the big weight
00:13:3300:13:35
belts and they it's like pull them as tight as they can before they get
00:13:3500:13:42
underneath something like a squat, that's what this muscle is supposed to do. it's
00:13:4200:13:50
supposed to cinch everything up ,which what that ends up doing is increasing
00:13:5000:13:54
intra-abdominal pressure.
00:14:1000:14:17
It also tightens this piece of fascia back here right, this thoracolumbar
00:14:1700:14:22
fascia, it pulls it like this really tight. Is that gonna help stabilize my
00:14:2200:14:27
lumbar spine? A little bit - yeah. It's like having guy wires on each side just
00:14:2700:14:32
getting pulled really really tight So it'll increase stiffness in the
00:14:3200:14:34
thoracolumbar fascia.
00:14:4600:14:54
TLF not to be confused with the TFL right, we think that these two things
00:14:5400:15:04
together increase the stabilization of the lumbar spine so that make sense.
00:15:2100:15:24
Now there's some varying opinions on how effective that is,
00:15:2400:15:29
but if you guys want to write down a couple researchers there's, I know
00:15:2900:15:36
some of you guys are way into the core you got Richardson Hodges and Heinz, so
00:15:3600:15:44
I'm gonna put Richardson et al. Then there's another guy named McGill who has
00:15:4400:15:52
a little different theory, and then another guy named Liebenson who has
00:15:5200:16:01
more research and a different approach. A lot of stuff out there. You guys heard of
00:16:0100:16:04
your multifidi.
00:16:0600:16:12
Yeah so your multifidi are interesting little muscles, they're
00:16:1200:16:24
fairly deep and they go from spinous process to transverse process. Spinous
00:16:2400:16:28
process-transverse process, spinous process-transverse process. Very
00:16:2800:16:33
segmentally. They're on the back of the lumbar spine
00:16:3300:16:41
so what joint actions do you think they do? Extension, sure they have an obliquity
00:16:4100:16:47
so what else might they can contribute to? Rotation.
00:17:0300:17:23
So we got extension, rotation, and what we believe that's really important about
00:17:2300:17:27
these muscles, these aren't the big extensors of the lumbar spine right.
00:17:2700:17:32
These little tiny muscles that you see in those pictures, but they have
00:17:3200:17:35
something different than the other extensors we're about to talk about,
00:17:3500:17:42
which is they're segmentalIy innervated. They cross only a couple segments at a
00:17:4200:17:48
time, so we think they're important for what we call segmental stabilization.
00:17:4800:17:55
Which is basically, if you thought of your lumbar spine like Jenga, you guys
00:17:5500:18:01
know the game Jenga, right you got to keep all your bricks stacked up, So if
00:18:0100:18:11
these were the bodies of my lumbar vertebrae right, I got my five little
00:18:1100:18:19
blocks there, what we think these muscles do is when movement or pathology or
00:18:1900:18:27
dysfunction cause our blocks to be this way,
00:18:3200:18:40
it might be these muscles that aren't doing their job. When movement causes us
00:18:4000:18:44
to do something like that, one of our blocks to move out of place, we think
00:18:4400:18:52
that these muscles doing their job will cause these blocks to do what? Straighten
00:18:5200:18:59
back out again, does that make sense .So your multifidus
00:18:5900:19:06
basically keep your blocks aligned. You guys ever heard the term segmental
00:19:0600:19:13
stabilization? No. You would. That's segmental stabilization. All we're
00:19:1300:19:17
talking about is keeping our block stacked on. It's a pretty bad thing right,
00:19:1700:19:23
if one block slides over the other starts moving out of place, instinctively
00:19:2300:19:29
guys do you think that's a good thing? No probably not. So we think the multifidi
00:19:2900:19:36
have a big role in this. This is the joint actions they'll help with, but
00:19:3600:19:39
this might be their more important function. Just like when we talked about
00:19:3900:19:42
the rotator cuff, we talked about the rotator cuff doing external rotation,
00:19:4200:19:47
internal rotation, abduction. But what was their important function? Dynamic
00:19:4700:19:51
stabilization of the shoulder right. Same thing with the multifidi and the
00:19:5100:20:01
TVA, they have an action, but their function-stabilize the lumbar spine.
00:20:0200:20:07
Alright let's look at another big mover.
00:20:1100:20:19
No no so the multifidi are very deep and lie right against the the facet joints
00:20:1900:20:25
of the lumbar spine. Your TVA actually more or less stops at the thoracolumbar
00:20:2500:20:32
fascia. Your multifidi there's layers to the thoracolumbar fascia it lies with,
00:20:3200:20:38
sandwiched between a couple of those layers. Does that kind of make sense? I got a
00:20:3800:20:41
bunch of pictures online, if you guys go to those muscular Anatomy articles, you
00:20:4100:20:45
look up multifdi, you look up transverse abdominus; I have tons and
00:20:4500:20:48
tons of pictures showing like cross-sections and stuff, so you get a
00:20:4800:20:57
good idea of where all of this stuff exists relative to something else. The
00:20:5700:20:59
erector spinae.
00:21:0200:21:07
Alright I'm going to ask a question knowing that I'm probably going to get
00:21:0700:21:14
twelve-year-old laughs out of it, what does it mean to erect something? To
00:21:1400:21:32
stand it up right. So if my erector spinae will erect me or stand me back up
00:21:3200:21:37
and I started down here, what joint action is that for the spine?
00:21:3700:21:49
It's extension. I like the erector spinae. I like the
00:21:4900:21:53
little muscles of the back the erector spinae, even the multifidi, I just like
00:21:5300:21:57
the way they're shaped, I think they're shaped cool, you know what I'm talking about? Looks
00:21:5700:22:01
like an upside down Christmas tree.
00:22:0100:22:07
Alright so if only this side of the erector spinae contracted, what would
00:22:0700:22:15
happen to my spine? Yeah contribute just a little bit to lateral flexion.
00:22:2900:22:37
You guys realize how long your erector spinae are? Yeah exactly, so just keep in
00:22:3700:22:43
mind all the way down to your sacrum, all the way up to your mastoid process,
00:22:4300:22:48
depending on which of the erector spinae muscles we're talking about. Another
00:22:4800:22:51
thing to keep in mind, something once you guys start digging a little deeper into
00:22:5100:23:01
your Anatomy is, is there one erector spinae muscle? Yeah, is there only one
00:23:0100:23:06
erector spinae muscle? Yeah there's actually three, and they all do a
00:23:0600:23:13
slightly different thing. So you have your spinalis, your iliocostalis and
00:23:1300:23:20
your longissimus. You know at this level your okay calling it the erector spinae.
00:23:2000:23:25
Like I said your next level once you guys get into graduate school, you start
00:23:2500:23:29
tearing things apart, maybe do some cadaver work, you're gonna start needing
00:23:2900:23:35
to know all of the different erector spinae muscles.
00:23:4000:23:54
How many pushups per ring? I'm going to make you start dancing if it happens again.
00:23:5400:24:01
You have to dance until you get your ringer to stop. Alright so what do I mean
00:24:0100:24:07
by bilaterally and unilaterally, great question. So bilaterally means what? Both
00:24:0700:24:14
sides. If both sides of my erector spinae fire at the same time, what are they
00:24:1400:24:17
going to do? They're going to pull down on my spine,
00:24:1700:24:21
pull down on my ribcage and I'm going to do this. But if only one side
00:24:2100:24:26
unilaterally right, like unicorn one horn right, unilaterally pull down, what's
00:24:2600:24:36
going to happen to my spine? This. Well we could see, this is where the layers come
00:24:3600:24:41
in right, if we start dividing out these erector spinae muscles we'll see that at
00:24:4100:24:46
least one of them will contribute a little bit to rotation, and that's one of
00:24:4600:24:52
the larger erector spinae muscles being your iliocostalis. Usually when you see
00:24:5200:25:01
that word cost, C O S T, costa, costol right it has to do with the ribs. Iliocostalis
00:25:0100:25:05
is the big erector spinae muscle which goes into the ribcage, and it probably
00:25:0500:25:09
can cause a little bit of that rotation.
00:25:1400:25:20
Yes yeah it kind of looks like a Christmas tree depending on which one
00:25:2000:25:28
we're talking about, but it'll be like the iliocostalis does this right. The
00:25:2800:25:34
spinalis just goes from spinous process to spinous process like this.
00:25:4000:25:44
The function of this class guys is to is to get down the joint actions. I'm
00:25:4400:25:48
excited though because you guys are starting to ask deeper and deeper questions. But
00:25:4800:25:52
as I kind of mentioned earlier when we were just warming up and going through
00:25:5200:25:57
our Q&A today, this doesn't ever stop. It's one of the exciting things about
00:25:5700:26:03
getting into this field is, like there are, we keep calling rabbit holes right.
00:26:0300:26:07
There are rabbit holes to jump down forever, you find something you're into
00:26:0700:26:11
you can just keep going, as I mentioned those those functional Anatomy articles
00:26:1100:26:18
that I have up on my site, talking like six seven pages of text on one muscle,
00:26:1800:26:26
and then pictures, and videos and illustrations and diagrams, and research.
00:26:2600:26:30
Depending on what muscle you talk about you may have hundreds of research
00:26:3000:26:38
studies to look at. Fun stuff. Quadratus lumborum,
00:26:4600:26:59
how many of you guys have heard of this muscle before? Cool, so this muscle goes
00:26:5900:27:07
from my 12th rib to my posterior ilium. The thing I want you guys to keep in mind
00:27:0700:27:14
though, this isn't a superficial muscle like out here,
00:27:1400:27:19
it's a twelfth rib to posterior ilium with some connections into these
00:27:1900:27:25
transverse process; it's actually a very deep muscle, comparatively. Your erector
00:27:2500:27:31
spinae are on top of them, your latissimus dorsi, transverse abdominus,
00:27:3100:27:36
internal and external oblique, on top of them. So it's fairly deep it's like just
00:27:3600:27:42
like this. What joint action do you think it's going to cause? Lateral flexion.
00:27:4200:27:52
Anything else? Where would it have to be to cause extension? They'd have to be
00:27:5200:27:54
here right, they'd have to be somewhere behind
00:27:5400:27:59
the lumbar, at least on the spinous process, be behind the bodies of the vertebra,
00:27:5900:28:05
this is right here. No rotation, what would it have to have to do rotation?
00:28:0500:28:10
Some sort of obliquity, come forward a little bit, this is this is lateral
00:28:1000:28:17
flexion. In fact your quadratus lumborum is your primary lateral flexor. This
00:28:1700:28:23
exercise -quadratus lumborum exercise, a little bit of oblique but quadratus
00:28:2300:28:30
lumborum. Sure quadratus lumborum is very important for stability. It is
00:28:3000:28:33
one of those muscles we've kind of talked about though like the iliacus,
00:28:3300:28:42
that has a propensity to get tight. If the quadratus lumborum got tight,
00:28:4400:28:52
what is that going to do? It could pull you this way if it's one side, if it pulls on
00:28:5200:29:00
both sides what's it going to do? Yeah it could, it could start to compress and
00:29:0000:29:04
give you a little soreness, eventually contribute to maybe some pain and
00:29:0400:29:11
dysfunction, you guys see how that would work. I'm not, I totally agree that the
00:29:1100:29:15
quadratus lumborum is important to stabilization. Is this a muscle that I'm
00:29:1500:29:21
going to write down and exercise for in a routine? Probably not. I don't think
00:29:2100:29:25
this is something we have to individually strengthen, and I think
00:29:2500:29:30
targeting it too hard might help contribute to that cycle of
00:29:3000:29:35
this muscle getting a little overactive, a little tight, and contributing to some
00:29:3500:29:42
of that low back pain that we see in so many individuals. This exercise
00:29:4200:29:48
we'd never give anybody, and not just because it makes people look silly, like
00:29:4800:29:52
they're trying to impersonate a wheel wobble, I think it contributes to low
00:29:5200:29:59
back pain. Oh you guys didn't think you'd go a whole hour without doing a graph
00:29:5900:30:08
did you? You know what that means though, we just did, you guys just finished all
00:30:0800:30:14
the muscles for functional anatomy one. So the one thing I think I mentioned
00:30:1400:30:19
there guys is the TVA, although it will play a role in all joint actions, it
00:30:1900:30:24
doesn't have a joint action so it's not going to end up on this graph. Don't forget
00:30:2400:30:31
about it though, that's what that little box at the top says. Action, plane, muscles,
00:30:3100:30:37
exercise that includes that joint action. So this one's a little bit more like the
00:30:3700:30:42
scapular graph we did. Whats that?
00:30:4300:30:55
TVA what about it? TV, TV-transverse abdominus. I'm sorry did I not define
00:30:5500:31:01
that? TVA, yeah TVA is transverse abdominus. Occasionally you'll see
00:31:0100:31:14
it as TA, what's the problem with that one? Tibialis anterior. Your transverse
00:31:1400:31:30
abdominus right, does that make sense? It just wraps around like this. he hasn't,
00:31:3000:31:33
he yes exactly.
Related Videos
Muscles of the Trunk: Video #19 of Introduction to Functional Anatomy
Dynamic Chop Pattern
Ball Crunch and Progressions
Static Up Chop aka Lift
Single Leg Chop Pattern
Core Anti-rotation - Opposing Chest Press and Row
Plank Progressions with Elbows on Ball
Static Ball Bridge with Trunk Rotation
Dynamic Ball Bridge with Trunk Rotation
Nervous System and Receptors 2: Video #24 of Introduction to Functional Anatomy
Pectoralis Major, Latissimus Dorsi and Teres Major: Video #10 of Introduction to Functional Anatomy
Functional Roles of Muscles: Video #25 of Introduction to Functional Anatomy
Muscles of the Lower Leg: Video #17 of Introduction to Functional Anatomy
Deltoid Muscles: Video #8 of Introduction to Functional Anatomy
Quadruped Crawl Sled Pull
Static Standing Chop Pattern
Transverse Abdominis (TVA) and Gluteus Maximus Activation and Progressions
Quadruped Progression (Gali-peds)