00:01
If we have movements,
there must be some muscles involved.
00:05
So we'll talk now about
the muscles of the back.
00:08
And we're gonna go
from superficial to deep.
00:12
And we're going to start
with a superficial layer,
because they're not really what we
might consider typical back muscles
in the sense that they
don't really move the back.
00:21
They really act
on the upper limb.
00:23
So they're really
something that is
involved in upper
limb movements.
00:27
But we'll mention them anyway,
because they're located in the back.
00:32
For example,
we have this roughly diamond-shaped
structure here
called the trapezius.
00:38
And this one's going
from the base of our skull,
along our spinous
processes of those vertebra,
unto a bone in a portion
of bone called the spine
of the scapula we'll learn
about in the upper limb.
00:51
And so that's going
to be helpful for
shrugging our
shoulders for example.
00:55
There are also these
muscles called the rhomboids
that are going to connect
our spinous processes
to the medial edge of that bone,
we'll learn later
called the scapula.
01:06
And when it contracts,
it's going to retract
or pull our scapula
towards the midline.
01:12
And then this
large broad flat one
is called the latissimus dorsi.
01:18
And it's running along the super
spinous processes out to the humerus,
which is the bone
of our upper limb.
01:25
And that's really
going to cause a lot of
adduction at our shoulder joint.
01:31
If we go a little bit deeper, though,
to a middle layer of muscles,
now we're getting into
muscles that act on the
back more directly,
more classic back muscles.
01:42
The first ones we see
are running vertically
on either side of
the vertebral column,
and they're called the
erector spinae group.
01:50
And erector kind of gives you
some idea kind of sounds like
moving up,
you're getting straight,
and that's going
to extend the back.
02:00
And they're very similar
if we look superiorly
with another group that almost
blends with it called the splenius group,
which is going to do the same
thing but more in the cervical area.
02:10
And so that's going to
be more neck extension.
02:14
Finally, if we go really deep
to the deepest layer,
where we're just connecting
between tiny little portions
of the vertebral column itself.
02:23
We have some small
ones and we'll point out two
there's Multifidus
and Rotatores.
02:29
And multifidus just means many
and that's probably not helpful.
02:31
But rotatores probably gives
you some idea of what it's doing.
02:34
And multifidus is really
stabilizing the spine.
02:38
And rotatores really a small one
helping with our rotational movement.
02:43
If we go so deep that we're
not even in the back anymore,
but we're reaching
the posterior abdomen.
02:49
We'll talk about
some other muscles
that really aren't
back muscles but
are important to just
know that they're nearby.
02:56
So if we go all the
way through the back,
we reach a muscle that's
in the posterior abdomen
called the quadratus lumborum.
03:04
And that's going to connect
to the top of our pelvic bones
called the iliac crest and
our bottom rib the 12th rib
and it's going to also
connect to our lumbar vertebra.
03:16
So not everything
connects to the
vertebra our back
muscles necessarily.
03:22
And it's going to do some of the
movements we mentioned already,
such as the lateral flexion
of the vertebral column.
03:28
Similarly, on the other side,
we have a muscle that we're
gonna learn about in the abdomen
called transversus abdominus.
03:34
It's definitely not a back muscle,
it's an abdominal muscle.
03:37
But we can see that it wraps
all the way around to the back.
03:43
If we go to an
anterior point of view,
we have these large muscles
here are called the iliopsoas.
03:49
And they're also attaching
to the lumbar vertebra
despite not being back muscle.
03:55
And they're
actually hip flexors.
03:57
And when we talk
about the lower limb,
we'll see they're
very strong hip flexors.
04:01
But they can act on the trunk as well,
if for example,
you fix the feet,
and then you flex this muscle,
instead of moving at the hips
and moving the leg upward,
it's going to move the torso.
04:14
So it's essentially like if you
were lying down on the ground,
and you had someone
sitting on your feet,
and you activated your iliopsoas,
you would do a sit up,
and it would seem as if
you're moving your torso.
04:26
And so this kind of brings
us to this concept of the core,
it's a very nebulous thing that
really isn't just back muscles.
04:34
We think of the core is something
that provides a lot of stability
to our torso and
our body overall.
04:39
And there are a lot of back
structures that are a part of it,
such as multifidus,
and in bony terms, the sacrum.
04:47
But we also have
abdominal muscles anteriorly
and other structures
in the pelvis,
like the pubic symphysis
we'll learn about
that are also part of
the core and basically
complement the stuff that
we've learned in the back.
05:00
So for example,
we see some of them here,
we see that abdominal
muscle transversus abdominis.
05:05
Even though it's an
abdominal muscle,
it goes all the way
around to the back,
and it connects
to our back fascia.
05:11
So in a lot of ways,
it's hard to really
separate abdominal
and back function.
05:16
We can see it's
also connecting to
the lower ribs
connecting to our thorax.
05:20
It's connecting to this
bone that we're going
to learn called the
illum that's in our pelvis,
and really is helping connect
everything hence the term core.
05:29
And what the core does,
in this sense is also
compressing and supporting
our abdominal wall
in addition to our back
and helping make sure everything's
stabilized and essentially using
as little energy as possible to
keep us in a nice neutral position.