So let's talk about joints of the
shoulder girdle. We just learned all
these joint actions and now I'm going to throw a little wrench in our joint
actions chart, but joint actions of the shoulder girdle are acromioclavicular joint
and our sternoclavicular joint. Now those sound
like really huge, technical words, well remember when I was talking about
anatomy being another language, those aren't huge technical words, they're
actually referring to two specific bones or two specific points with on a bone.
Your acromioclavicular joint everybody feel this right here, feel that shelf
where you don't have any de ltoid, it's just above your deltoids, it
doesn't matter how big your deltoids are you still don't have deltoids here.
Right here you feel the shelf, well that's part of your scapula called your
acromion process. What's this bone right here called? This is your
clavicle, your collarbone it's your clavicle, so where your acromion
process and your clavicle meet is called your acromioclavicular joint. That's it,
it's not so bad right. It's like when you try to smash words together, you guys
ever do that, like you see a cute couple and you like try to smash the girls name
and the guys name together, you guys ever done that before? Right don't they do
that with like stars, huh Kimye, awful, terrible. Anyway, but you get what
I'm saying, that's all they've done here, taking acromion and
clavicular and said, "You know what'd be really cute? If we call it acromioclavicular."
That's the name of the joint, for short it's AC joint. Sternoclavicular, what do
you think sterno is related to? Sternum and the clavicle feel right here,
do a little of this, you can kind of feel there's a joint right here.
The funny thing is is your entire shoulder girdle including your
arm, the only bony attachment to your body is this joint right here. Craziness.
That's crazy. Alright so that's your sternoclavicular
joint. Now although those are the two joints of the shoulder girdle, we don't
usually refer to motion of these joints. In further classes you will, those of you
guys going back for your ATC, your DPT, master's in kinesiology, you'll start
looking at these joints specifically, but for the most part those two joints help
to dictate motion of the scapula, and we refer to motion of the scapula in
analysis. Most of the muscles that would even impact these joints are actually
attached to the scapula, does that make sense? So I don't want you guys to think
that the scapula is a true joint, sometimes it's called the scapulothoracic joint.
It's not actually a true joint, it's just more convenient to label
it that way. Now unfortunately you guys just learned all of these joint actions
right, flexion, extension, abduction, adduction, horizontal abduction, adduction
external internal rotation, lateral flexion, you learned all that. The
scapula doesn't use those, so we have to learn a separate set of joint actions.
You ready? They're actually not that bad. Most of them occur in the frontal
plane. Does anybody want to take a wild guess why most of them would occur in
the frontal plane? Think about how I taught you guys the frontal plane.
The muscle, the way the muscles run, that's part of it. I told you to think about the
frontal plane as if you had what? A plane of glass in front of you. What's in
front of the scapula? The ribs. Is there going to be a whole lot of sagittal
plane motion of the scapula with ribs in front of it? Now that kind of makes sense.
So our frontal plane joint actions, our scapular joint actions rather
that's my scapula everybody cool with that, all right start with this. If I go
up it's called elevation, because elevators take you up, I know they can take
you down too but stay with me. So elevation is up, that makes sense right
that's not too bad. What do you think the opposite of elevation is? Depression.
Don't most people who are depressed kind of have their shoulders down anyway.
Okay so we got elevation, we have depression.
The next joint actions you kind of have to think of the scapula as a pinwheel.
You remember pinwheels? They were these little, there was like a stick,
stick, right then they had these like leafy things, how's my art coming?
Is it getting better? Better than the horizon, that kind of looks like a
pinwheel and you'd like blow on it and it would spin, you know what I'm
talking about? Or am I just totally dating myself at this point. Pinwheel?
You have to kind of think of it as a pinwheel, it's a type of rotation
although it's a rotation in the frontal plane this way, known as upward and
downward rotation. Now to decide which way is up and which way is down we need a
point of reference, you with me? That point of reference for the scapula is
your shoulder socket, this part where my humerus hangs down my arm, this is known
as your glenoid fossa. When your scapula spins so that we end up with
glenoid fossa pointing upward, which rotation do you think that is? That's
upward rotation, moving back down is going to be downward rotation. What do
you think we see these joint actions, anybody want to take a guess? Frontal
plane motions sure, give me an exercise? Shoulder press would be what? Upward
rotation, when would I see downward rotation? Pull up, so if
I'm doing a pull-up, my scapulae are starting to do this, which is that downward
rotation. Has everybody got that visualized? Alright let's talk about the
If I drew you from the top, this is your torso this is your head, sorry if any of
you are offended by this picture I don't mean anything by it, not that big, it's my
torso. So we got torso head and then we got scapula, it's a great picture isn't
it. If I do this, all right if I do this thing, so in essence I go from here to
here, can you see how that would be transverse plane movement? Parallel
to your table since this is a top-down view. Now the question is what do we call
that? This is protraction. How many of you have seen this guy in
the gym, you can now refer to them as Captain Protraction. No? None of you
are that nerdy? Any of you know what ILS stands for? This is a good one
too, you don't know ILS? "Imaginary Lat Syndrome." You can throw
that around amongst yourselves. So protraction, what action, what
exercise might we see a little protraction in? Benchpress sure, we really
need protraction to bench pres. In fact, anytime we do pushing motions, we need
some protraction. What's the opposite of protraction? Retraction, so that's
when my scapulae actually come closer together and almost touch in the middle.
We got the green as protraction, when we got red we got retraction.
Those six joint actions are your big joint actions for the scapula,
those are the ones you will see most often, you guys cool with that? Now there
is two other joint actions for the scapula that you don't run into as often
in your textbooks. Those of you who continue with my courses you're going to
have to be aware of, which is there is one set of sagittal plane motions for
the scapula. It's called anterior and posterior tipping. So we won't refer to
this too much for the rest of the day, you can put a little star by this,
as bonus material, but if I drew a skeleton from the side,
all this are my vertebrae, how you like my picture? Good. Scapula sits just
like this. Now anterior and posterior tipping is sagittal plane motion, which
means it's in which direction? Forward and back right? So what happens with the
scapula is it can kind of crawl over the top of the rib cage, and it can tip
anteriorly. Alright so when we refer to this tipping it's in reference to the
top of the scapula, and then what would be the opposite of anterior tipping?
Posterior tipping, exactly. So that would be posterior tipping. When we get into a
little bit more complex postural dysfunction and correcting postural
dysfunction and improving mechanics of the the upper body, this becomes
important. Everybody's got those? Anybody want to take a guess when anterior and
posterior tipping happens, like some exercises? Shrugs, yeah you don't really
force it in a shrug. It's probably going to be more like an arm motion that
anterior and posterior tipping gets included in, anybody want to guess?
Swimming possibly, when during the swim? So if I do this, what's going to
happen to my scapulae? They're going to posteriorly, do it, do it, you can feel your
scapulae push into your rib cage, it flipped this way, so that's
posterior tipping. Anterior tipping is, yeah if you did one of these
things, everybody do this, because it looks hot, like Kimye,