You can only view 3 videos without an account. Become a Member to access all videos on the website.
Pectoralis Major, Latissimus Dorsi and Teres Major: Video #10 of Introduction to Functional Anatomy
Pectoralis Major: The pectoralis major is a large muscle found in the chest. It arises from the clavicle, sternum, and ribs and inserts into the humerus. It is involved in shoulder flexion, adduction, and internal rotation. Latissimus Dorsi: The latissimus dorsi, or "back muscle," is a large muscle found in the middle and lower back. It arises from the spinous processes of
Transcript
00:00:0500:00:15
Pectoralis major, how major, what does
00:00:0500:00:15
major mean? Here's the weird thing about
00:00:1500:00:20
pectoralis major there's a pectoralis minor right, we already went over it.
00:00:2000:00:25
Pectoralis major crosses what joint?
00:00:2700:00:31
Pectoralis major crosses the shoulder, what does the pectoralis minor cross?
00:00:3100:00:40
Scapula, they're not even related, I don't know how that works, but we got pectoralis
00:00:4000:00:48
major crosses the shoulder so do we have the right word bank up? Yeah we got the
00:00:4800:00:53
right word bank up right that's the shoulder word bank. Flexion, extension,
00:00:5300:01:02
abduction, adduction. Can my pectoralis major do upward rotation? No, that's a
00:01:0200:01:15
scapular joint action. So we have this pec that goes from sternum and clavicle,
00:01:1600:01:25
we're going to draw the glenoid fossa here to the humerus, everybody with my
00:01:2500:01:30
diagram. I try to get fancier but we know what happens when I get fancier, it just
00:01:3000:01:40
looks messy. So my pec goes kind of like this, we have some fibers that come in
00:01:4000:01:48
from the clavicle, and then some fibers that come in from the sternum, kind of
00:01:4800:01:55
looks like a pec right. Most of those fibers run in what direction? Horizontal.
00:01:5500:02:01
Okay so let's start what are our horizontal plane joint actions?
00:02:0300:02:13
Horizontal abduction, adduction. So those are our horizontal joint actions, what do
00:02:1300:02:23
you think the pec will do of those joint actions? Horizontal AD or horizontal AB?
00:02:2300:02:32
AD-duction yeah, your pec is your primary horizontal adductor. Alright so
00:02:3200:02:36
it attaches to the front of my arm here,
00:02:3600:02:43
what do you think it's going to do as far as rotation? Internal rotation, cool.
00:02:4300:02:50
Alright then we get a little tricky, we have a clavicular head and a sternal
00:02:5000:03:12
head. So this clavicular head it runs like this, what muscle does it kind of
00:03:1200:03:15
run parallel to?
00:03:1900:03:26
Anterior delt right, what does my anterior delt like to do? Flexion, do you
00:03:2600:03:31
think these portion of my pec could at least assist a little bit in flexion?
00:03:3100:03:45
Everybody do that, like help out, sorry did not mean to be quite that sarcastic,
00:03:4800:03:53
can you guys feel that contracting a little bit? So if you do shoulder flexion
00:03:5300:03:59
the clavicular head of your pec can help out a little bit.
00:04:1400:04:20
Sternal head, now we got some fibers that run this way right, they kind of have
00:04:2000:04:23
more of like a downward angle, what other joint action do you think they could
00:04:2300:04:30
help contribute to? A little bit of adduction yeah, sure I mean directly it
00:04:3000:04:36
would be diagonally but that's a little adduction right. How many you guys have
00:04:3600:04:40
done cable crossovers for your lower pecs? There's no such thing as lower
00:04:4000:04:45
pecs but you do have a sternal head of your pec right, so yeah a little bit of adduction.
00:04:4500:04:57
You guys know who Hulk Hogan is? Yes right Hulk Hogan used to do what
00:04:5700:05:11
when he got into the ring? I think we found a Hulk Hogan fan all right, yeah
00:05:1100:05:16
but he used to show off his pecs right, he used to do that whole arghh. Well if
00:05:1600:05:22
you're going to show off your pecs can you do horizontal adduction? No because your
00:05:2200:05:27
mammoth 19 inch pythons get in the way, right you want people to see them so how
00:05:2700:05:35
do you contract your pecs? With a little bit of adduction, you guys got how that
00:05:3500:05:45
works. Probably not a rate great way to show off the clavicular head right, but a
00:05:4500:05:53
good way to show off the sternal head that make sense. So next muscle, you guys
00:05:5300:06:01
destroyed the pec, oh exercise graph, let's do chest fly.
00:06:1500:06:24
What joints are moving? Glenohumeral joint, are we stay in fancy with this.
00:06:2800:06:40
Glenohumeral and, yeah it would be SC and AC joints, would be the shoulder girdle,
00:06:4000:06:49
those are the joints that are moving, aka the scapula thoracic joints,
00:06:4900:06:58
scapula thoracic. We've just been calling it the scapula for ease. All right joint
00:06:5800:07:06
actions, so this is horizontal adduction we're adding to the midline in
00:07:0600:07:21
the horizontal plane. What's going on at my scapula? Protraction good. Muscle cause,
00:07:2100:07:25
muscles that do horizontal adduction,
00:07:3000:07:39
pec well, pec major will do horizontal adduction both heads. Who else?
00:07:4200:07:48
Anterior delts, how many of you guys have been a little short sore on your
00:07:4800:07:55
shoulders after a bunch of chest work? A little bit yeah yeah. Protraction, who does
00:07:5500:08:10
protraction? Serratus anterior and pec minor cool, a lot going on in a chest fly.
00:08:1300:08:20
This is not internal rotation, what's internal rotation? Yeah this is internal
00:08:2000:08:25
rotation, so unless you do this with the weights, don't do that with the weights
00:08:2500:08:33
it's not going to help anything, it's not internal rotation, does that make sense?
00:08:4100:08:50
All right I think latissimus dorsi is up next. Latissimus dorsi which roughly
00:08:5000:08:58
translates to widest back, this is the biggest muscle on your upper body and it
00:08:5800:09:09
is a big muscle. You see it's it's origin is all of this right, it goes all the way
00:09:0900:09:17
from like posterior, iliac spine part of your pelvis, all the way up to T7, so mid
00:09:1700:09:23
thoracic spine, a lot of attachment area. And then all of that thoracolumbar
00:09:2300:09:30
fascia in between, and then its insertion is the intertubercular groove of the
00:09:3000:09:39
humerus, which is the groove between the two bumps on the humeral head, good call.
00:09:3900:09:47
Alright so this is a big muscle on the back, goes from here wraps around the
00:09:4700:09:52
ribcage, inserts into the front of the humerus, all right so what is it going to
00:09:5200:10:00
do to the to the arm, what is going to do the shoulder? When this muscle contracts,
00:10:0100:10:06
adduct, how'd you come up with adduct?
00:10:0900:10:16
Well contract contract right, so if it shortens this way, right from up here, is
00:10:1600:10:20
that going to pull my arm down in adduction? Yes in fact that exercise is
00:10:2000:10:25
known as a lat pull down.
00:10:3800:10:45
What else is it going to do? What if I start with my moves, but what if I start
00:10:4500:10:53
with my arms up here? Will it pull me down, sure so what joint action
00:10:5300:11:03
is that? Extension. Alright this is a muscle that goes from the back to the
00:11:0300:11:13
front of my humorous right. Internal rotation or external rotation? Ooo...
00:11:1300:11:19
divided. Alright so this muscle wraps around here and then attaches in like
00:11:1900:11:23
this. How many of you guys say internal rotation? How many of you guys say
00:11:2300:11:34
external rotation? All right do you mind standing up being my model real quick? So
00:11:3400:11:39
if I'm her latissimus dorsi, and I reach around like this and grab the
00:11:3900:11:45
inside of her arm right, stop moving, all right I grab the inside of her arm like
00:11:4500:11:51
this and I shorten, which way am I going to rotate her? Yeah internal rotation,
00:11:5100:12:01
weird huh, this muscle on the back comes like this and pulls down this way right,
00:12:0100:12:07
see how that works, so internal rotation thank you.
00:12:1600:12:20
Let me show you why knowing your functional anatomy is important, how many
00:12:2000:12:25
of you guys do push-pull days in the gym, little old school but a lot of guys
00:12:2500:12:28
will still do chest and back together because I think they're opposites and
00:12:2800:12:35
all that fun stuff. What do they work, so their lats is what they're doing on their
00:12:3500:12:42
back right, and then pecs are on the front, are these muscles truly opposite?
00:12:4200:12:56
What does my pec do again? Horizontal adduction, adduction, internal rotation
00:12:5600:13:12
and adduction right. These muscles opposites? Not really, so then we wonder
00:13:1200:13:16
why certain individuals who don't do enough of balance work, and don't do
00:13:1600:13:22
enough flexibility work and enough to correct some of the dysfunction they
00:13:2200:13:29
create, walk around like this right we talked about Captain Protraction, aka
00:13:2900:13:37
ILS right, if all you're doing is pecs, pecs, pecs, pecs and then all your back
00:13:3700:13:44
work is lats, lats, wouldn't it make sense that eventually you'd start
00:13:4400:13:52
getting a little internally rotated at the shoulder joint? Something to think about.
00:13:5400:14:10
Teres major, teres major goes from lateral border of my scapula wraps
00:14:1000:14:21
around into the front of my humerus, very similar fiber direction to who? My
00:14:2100:14:29
lat, so guess what my teres major does? All of the same joint actions right, this
00:14:2900:14:34
is your lats little brother. Any of you guys have younger siblings who wanted to
00:14:3400:14:41
do everything you did, the only thing the teres major won't do is what the lat
00:14:4100:14:47
does at the lumbar spine which we'll talk later about with core, that make
00:14:4700:14:54
sense. Now so teres major does internal rotation, adduction, extension, we said
00:14:5400:14:59
there was a teres minor, what does the teres minor do? External rotation because
00:14:5900:15:09
it's part of what? The rotator cuff and we know that it externally rotates. You guys see
00:15:0900:15:13
how that works? So I gave you that little teaching cue of remember teres minor
00:15:1300:15:18
helps out lesser smaller muscles being the rotator cuffs. I think of the teres
00:15:1800:15:23
major is helping out a major muscle, the largest muscle on my upper body, and
00:15:2300:15:29
that's how I keep the internal rotation of teres major straight and the
00:15:2900:15:33
external rotation of teres minor straight, does that help you guys a
00:15:3300:15:43
little bit? Good make a note somewhere, highlight, and then do this graph.
00:15:4300:15:49
Internal and external rotators of the upper body, remember when I said put a
00:15:4900:15:59
star by certain graphs, this is one of them. Internal and external
00:15:5900:16:08
rotators of the shoulder, this covers a lot of your shoulder muscles, give you a
00:16:0800:16:11
good idea on how this stuff works.
00:16:1300:16:28
Internal rotators of the shoulder, subscapularis nice, anterior deltoid try
00:16:2800:16:32
try to keep these in order of size here,
00:16:3600:16:43
I'm missing some big ones, pectoralis major,
00:16:4400:16:58
if teres major does it who else does it? Lats right, teres major and
00:16:5800:17:09
who mmm IT what, it externally rotates right so infraspinatus and who else?
00:17:2400:17:32
That graph does not look balanced to me right if we just match these up for size
00:17:3200:17:39
let's say the teres minor and teres major are roughly the same size,
00:17:3900:17:44
infraspinatus and subscapularis roughly the same size, posterior and anterior
00:17:4400:17:51
delt roughly the same size, is there any external rotator as big as the lats as
00:17:5100:17:59
big as pec major so the two largest muscles on your upper body are both
00:17:5900:18:04
internal rotators, does it make sense why we've never seen the postural
00:18:0400:18:09
dysfunction shoulders externally rotated?
00:18:1100:18:15
Never actually seen that postural dysfunction. I'd be I think it'd be
00:18:1500:18:22
excited if I did see it, like wow I didn't even know if that could happen. Yeah it
00:18:2200:18:26
doesn't help that posteriorly we want to be here, we talked about some of our gym
00:18:2600:18:30
activity might be a little biased towards this internal rotation thing, and
00:18:3000:18:35
now we're learning that there's a third reason, maybe a structural fault in the
00:18:3500:18:43
human body that kind of biases, biases us towards internal rotation. Does that make
Related Videos
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