Alright deltoids, we have three
deltoids. We have upper, upper how many
guys have an upper deltoid? Yeah I didn't think so, freak, what are you doing
with an upper deltoid. All right anterior, one of my big pet peeves middle
not medial, you don't have a medial deltoid, that's a mistake I see actually
in text books all the time, medial deltoid yes that makes a lot of sense
for the most lateral structure on your torso. Alright anterior, middle
and posterior. These are kind of tricky, your anterior delt goes from, where
was slim, let me get slim.
You guys know slim?
I don't know why you guys buy the real bone skeletons, they are so fragile,
they're super expensive too. You figure after all the years that people have
been using skeletons they'd come up with something a little bit more durable. Yeah
all right this is slim, in case any of you wonder why I started working out to
begin with this is what I looked like in high school. I had the body of a model
when I started high school, a female runway, model it was terrible, no joke I
started 6'1, 145 pounds, my freshman year. Not okay, they tried to duct-tape me
to a pole and I started lifting weights, that's that's the story of how I became
a personal trainer. All right so this is slim, your anterior delt goes from this
right here the edge of your clavicle right, your acromion shelf wraps around
the front into something called your deltoid tuberosity, deltoid tuberosity
what's a tuberosity? A bone bump, and this is the bone bump that your deltoid
connects into. You guys can all find your deltoid tuberosity, just take your hand
palpate your shoulder right, palpate your deltoid, bring it down to the point right
here, there's your deltoid tuberosity. Not bad right, there you go. So this one kind
of goes and wraps around like this, so what joint does it cross?
Your glenohumeral, your shoulder joint. So all of these are going to be shoulder
joint actions right. So I'm just going to write shoulder up here, that means
technically we need a new word bank right, we can't use our scapular
actions for our shoulder. What's my word bank for my shoulder? So I got abduction
I got flexion, I got extension, internal rotation,
external rotation and horizontal AD and AB duction. So if I'm talking about the
shoulder it has to be one of those joint actions yes. Alright so let's go back
to the anterior delt, it's this way. So if it runs in front of my shoulder joint,
what joint action do you think it's going to contribute to? Flexion, good.
What if I do this, now where is it? Still in front of my shoulder right, but now
when it shortens how is it going to pull my arm? Horizontally, you guys got that.
Yeah so that's horizontal adduction. It also kind of wraps around my humerus too
right, wraps around just a little bit. Generally things that wrap around bones
or have an obliquity, obliquity is a diagonal to them, will contribute to some
sort of rotation. Which type of rotation do you think my anterior delt is going
to contribute to? Internal.
What do you guys think? Does that make sense? Touch your anterior
delt for me, all right now internally rotate, you feel that guy contracting a
little bit? Yeah. Alright so let's look at the middle delt, the middle delt is
the part of your deltoid that goes from acromion shelf and runs straight down the
side the deltoid process. So it runs up and down on the side of my body. What
plane did we say those muscles would probably work really well for? Up and
down on the side of my body, frontal plane right. So now we could take our
word bank and chop it down to just our frontal plane joint actions. Alright
you guys are 50/50, which joint action is this one going to cause when
it shortens? Yeah this is abducting away.
Posterior delt, so my posterior deltoid runs from the lateral aspect of the
spine of my scapula back down to deltoid process, and so now it runs up and down
on the back of my shoulder joint, what do you think it's going to contribute to?
Extension sure. What else, what if I did this, if I did this what is this exercise
called? A reverse or rear delt fly right, you guys have heard that before. So what
joint action is that? Horizontal AD or a AB? AB, horizontal abduction, and
what's this, this one's kind of got the wrap around thing happening right. Yeah so
since this one's back here though, if it shortens it's going to pull me into...
external rotation; and if you guys caught on, anterior and posterior delt what's
interesting about them? They're opposites right, anterior flexion, posterior
extension, anterior horizontal adduction, posterior horizontal abduction,