00:00:03
oh
00:00:03
sorry there just uh stretching out my
00:00:05
facial muscles so i don't pull a muscle
00:00:06
during this video which isn't about
00:00:07
facial muscles but it is about muscles
00:00:09
we have over 600 muscles in the body in
00:00:12
this video we're going to look at 15 of
00:00:13
those
00:00:14
15 common superficial muscles that
00:00:16
control the movement of different joints
00:00:17
like our elbow and shoulder joint we're
00:00:18
going to look at these muscles in terms
00:00:20
of antagonist pairs
00:00:21
how pairs of muscles working against
00:00:23
each other help us control each of the
00:00:25
joints in our body we'll learn some
00:00:26
movement terms such as flexion extension
00:00:28
abduction adduction rotation
00:00:30
we'll learn some origins and insertions
00:00:32
basically the points where the muscles
00:00:34
attach to bones that they're moving
00:00:35
and we'll learn the difference between
00:00:36
isometric and isotonic contractions
00:00:38
so we're only learning a small fraction
00:00:40
15 out of the over 600 muscles
00:00:42
but we're going to learn a lot of
00:00:43
concepts that go with these as we go
00:00:45
through all these 15. so let's jump to
00:00:46
the white board and get started all
00:00:47
right before we get into the muscles
00:00:49
themselves
00:00:50
there's several terms that we need to
00:00:51
learn we'll start with some movement
00:00:52
terms
00:00:53
the first one is flexion now flexion is
00:00:55
any time you're taking a joint
00:00:57
and you're decreasing the angle of it so
00:00:59
for example whenever you contract the
00:01:00
bicep muscle
00:01:01
and that bends the elbow that would be
00:01:03
an example of flexion
00:01:05
if you do the opposite movement and you
00:01:07
extend the elbow
00:01:08
or increase the angle of that joint then
00:01:11
we call
00:01:12
that extension so flexion and extension
00:01:14
are opposites of each other
00:01:16
flexion is whenever you decrease the
00:01:18
angle of a joint
00:01:19
extension is whenever you increase the
00:01:21
angle of that joint
00:01:22
and they're kind of opposite movements
00:01:24
for most of our joints and this idea
00:01:26
of opposite movements gets into one of
00:01:27
the big ideas of this video which is
00:01:29
antagonist pairs
00:01:30
in that example of bending and extending
00:01:32
the elbow joint we have an antagonistic
00:01:34
pair of muscles the biceps will flex the
00:01:37
joint or decrease the angle
00:01:38
the triceps have to do the opposite
00:01:40
movement and extend
00:01:42
the elbow joint if your bicep is
00:01:44
contracting then your tricep
00:01:45
is relaxing and vice versa and so we
00:01:47
call those an antagonist pair it allows
00:01:49
the joint to move one way
00:01:51
and then back the other way and it's
00:01:52
controlled by two different muscles
00:01:54
these two diagrams demonstrate those
00:01:56
terms if you have extension you're going
00:01:57
to increase the angle between the
00:01:58
humerus bone here
00:01:59
and the radius and the ulna by moving
00:02:01
the arm down this way
00:02:03
but if you flex that elbow joint you're
00:02:05
going to decrease the angle by moving
00:02:06
your radius and ulna or your
00:02:08
lower arm up this way and therefore
00:02:09
decreasing that angle between those
00:02:11
bones
00:02:12
so those are flexion and extension but
00:02:13
we have other motions that our joints
00:02:15
could do as well
00:02:16
one of those is rotation rotation is
00:02:18
just going to be turning a joint
00:02:19
and usually when we talk about rotation
00:02:21
we need to indicate a direction such as
00:02:22
i'm going to rotate my shoulders
00:02:24
medially
00:02:24
or i'm going to rotate my shoulders
00:02:26
laterally so we usually pair the word
00:02:28
rotation
00:02:29
with a directional term to indicate
00:02:30
which direction we're rotating that
00:02:32
joint
00:02:32
next we have the terms abduction
00:02:34
abduction is movement away from the
00:02:36
midline
00:02:37
so to abduct my arm i'm going to take my
00:02:39
arm and move it away from my midline
00:02:41
i think of this like being abducted by
00:02:42
aliens like you're getting taken away
00:02:44
from something it's taken away from the
00:02:46
midline
00:02:46
and the opposite of that is a very
00:02:48
similar sounding word adduction
00:02:50
and i just think of addition i'm adding
00:02:52
it back to my torso
00:02:54
so when i add duct to my arm i return it
00:02:56
back to my side or back to the midline
00:02:59
so i abduct the arm but i can also
00:03:01
adduct
00:03:02
the arm so even though those terms are
00:03:04
pretty similar i think there's a good
00:03:05
way to remember them
00:03:06
abduct and adduct those aren't all the
00:03:08
movement terms but those will be the
00:03:09
main five that we'll use in the muscles
00:03:11
that we're looking at in this video now
00:03:12
all muscles in your body connect to at
00:03:14
least two points
00:03:15
usually those are bones and all the
00:03:16
examples we look at here these muscles
00:03:18
will connect to different bones in the
00:03:19
body to pull on them and cause us to
00:03:21
move
00:03:21
the two bones that the muscles connect
00:03:23
to have names we have the origin and
00:03:25
this is going to be whatever bone
00:03:27
the muscle attaches to that doesn't move
00:03:29
the opposite of that is the insertion
00:03:31
the insertion is going to be the bone
00:03:33
that does move so if i think of bending
00:03:34
my elbow as an example
00:03:36
my biceps brachii muscle connects from
00:03:38
my scapula up here
00:03:40
down to my radius down here and whenever
00:03:42
that contracts
00:03:43
it's going to move the radius the radius
00:03:46
is the bone that actually moves so that
00:03:48
would be the insertion
00:03:49
the origin is going to be the bone that
00:03:50
doesn't move and that was the scapula
00:03:52
whenever i bend my elbow my scapula
00:03:54
isn't really moving right here
00:03:55
my radius is therefore my scapula is the
00:03:58
origin
00:03:59
and my radius is the insertion whenever
00:04:01
i'm trying to identify origins and
00:04:02
insertions
00:04:03
i find it helpful to identify the
00:04:05
insertion first because it's easiest to
00:04:06
tell what's moving
00:04:08
and then to go back and say okay what
00:04:09
would the origin be that this could be
00:04:10
pulling on
00:04:11
to cause that movement to happen so
00:04:13
origin doesn't move
00:04:14
insertion does move finally there's two
00:04:16
types of contractions that we're going
00:04:18
to look at
00:04:18
those are isometric and isotonic that
00:04:21
prefix
00:04:22
iso just means same so let's look at
00:04:24
isometric first
00:04:25
iso means same metric means length so
00:04:27
isometric means same
00:04:29
length and this is whenever you're
00:04:30
contracting a muscle but no movement
00:04:32
happens
00:04:32
so for example if i try to lift up on my
00:04:34
desk right now
00:04:36
i promise you this muscle is contracting
00:04:38
right now but nothing's happening
00:04:40
there's no movement happening right so
00:04:42
that would be an isometric contraction
00:04:44
i'm straining really hard but there's no
00:04:47
movement happening
00:04:48
so it's isometric same length or in
00:04:50
other words
00:04:51
no movement the opposite type of
00:04:53
contraction is isotonic and we're going
00:04:55
to look at more isotonic contractions
00:04:57
throughout this video
00:04:58
isotonic means the same force and this
00:05:01
is going to be when there is movement
00:05:02
happening so for example if i'm lifting
00:05:04
up this book and i can track my bicep to
00:05:06
do that
00:05:07
i'm applying the same force onto this
00:05:09
book as
00:05:10
i lift it up now if this book were
00:05:12
really heavy and i tried to lift it and
00:05:13
there was no movement happening
00:05:15
well then i would be changing the amount
00:05:16
of force that i'm trying to push up with
00:05:19
but if there is movement happening
00:05:21
that's happening with about the same
00:05:22
force the whole
00:05:23
length of the contraction so we call it
00:05:25
isotonic or same force
00:05:27
the main thing to remember though is
00:05:28
that isotonic contractions
00:05:30
are with movement isometric contractions
00:05:33
are with no movement
00:05:34
so with all that terminology out of the
00:05:36
way let's actually look at some muscles
00:05:38
whoa this person looks intense muscle
00:05:40
diagrams always look super intimidating
00:05:41
am i right
00:05:42
we'll move from the arms to the shoulder
00:05:44
to the torso and then down to the legs
00:05:45
so we'll start off with this this is the
00:05:47
biceps brachii
00:05:48
muscle the action of the biceps brachii
00:05:51
is to flex the elbow and we've seen that
00:05:53
in an example already
00:05:54
the origin of the biceps brachii is up
00:05:56
in the scapula and the insertion is
00:05:58
going to be the radius
00:05:59
so it's going to pull between the
00:06:00
scapula and the radius in order to flex
00:06:02
the elbow joint now its antagonist is
00:06:04
the triceps brachii the action of the
00:06:06
triceps brake guy is to
00:06:08
extend the elbow joint or to straighten
00:06:10
it back out the triceps brachii
00:06:12
originates at the proximal end of the
00:06:13
humerus
00:06:14
and it attaches to the proximal end of
00:06:16
the ulna and it's going to pull on that
00:06:18
ulna to straighten the elbow out
00:06:20
or extend the elbow so biceps brachii
00:06:23
triceps brachii
00:06:24
up next we have the deltoids and the
00:06:26
deltoids are your shoulder muscles
00:06:28
and their purpose is going to be to take
00:06:29
your arms and raise them now raising
00:06:31
your arms like that is an example of
00:06:33
abduction so abducting the arms is the
00:06:36
function of the deltoids
00:06:37
the deltoids originate in the clavicle
00:06:39
and the sternum and they insert to the
00:06:41
humerus
00:06:41
so they're going to pull like this to
00:06:44
lift up
00:06:44
the arm now the antagonist of the
00:06:46
deltoid is actually two different
00:06:48
muscles which we'll look at now
00:06:49
first we have the pectoralis major
00:06:51
muscle the pectoralis is going to rotate
00:06:53
your shoulders anteriorly
00:06:54
so whenever you can track these muscles
00:06:56
right here it pulls your shoulders
00:06:58
forward an example of a workout you can
00:06:59
do here is a pec fly on a machine
00:07:02
or it could be a bench press and you're
00:07:03
rotating your shoulders forward whenever
00:07:05
you push the weights out so the
00:07:06
pectoralis major
00:07:07
rotates the shoulders anteriorly the
00:07:09
antagonist of the pectoralis major
00:07:11
is the latissimus dorsi muscle the
00:07:13
latissimus dorsi is found in your lower
00:07:15
back on both sides
00:07:16
its origin is actually your lumbar spine
00:07:18
down here as well as your ribs
00:07:20
and it's going to connect to the humerus
00:07:22
up here in the arm and what it does is
00:07:24
it's going to pull on that humerus
00:07:26
back so it acts as an antagonist to the
00:07:28
pectoralis major
00:07:29
pectoralis major rotates your shoulder
00:07:30
forward latissimus dorsi rotates your
00:07:32
shoulder
00:07:33
backwards and sort of down or you could
00:07:35
say it rotates it
00:07:36
posteriorly now both of those muscles
00:07:38
pull your shoulders down a little bit
00:07:40
either down and forward or down and back
00:07:42
so together they work as the antagonist
00:07:44
to the deltoids which abduct the arm
00:07:46
so deltoids can abduct the arm
00:07:48
pectoralis major and latissimus dorsi
00:07:49
together
00:07:50
adduct the arm bring it back down to the
00:07:52
midline now another important muscle to
00:07:54
the shoulders is the trapezius muscle
00:07:56
the trapezius muscle is kind of in the
00:07:58
neck and the shoulders
00:07:59
back in this region right here its
00:08:01
origin is the thoracic and cervical
00:08:03
spine as well as the base of the skull
00:08:05
and its insertion is the clavicle in the
00:08:06
scapula and the trapezius is all about
00:08:08
moving your scapula
00:08:10
so if you move your scapula which is
00:08:11
back here around like this
00:08:13
you're using your trapezius in order to
00:08:15
do that okay that feels good i need to
00:08:17
stretch out my trapezius a little bit
00:08:19
all right from there let's move down to
00:08:20
the abdominal muscles we have the rectus
00:08:22
abdominis muscle
00:08:23
and that's going to be when you think of
00:08:24
abs you're thinking of the rectus
00:08:26
abdominis
00:08:26
this is your six pack your eight pack
00:08:28
your 10 pack your 12 pack bro
00:08:30
the movement of the rectus abdominis is
00:08:31
going to be to bend the spine actually
00:08:33
think about doing a sit up and your and
00:08:35
your spine sort of bends
00:08:36
that's the action of the rectus
00:08:38
abdominis and that's why doing an
00:08:39
ungodly amount of sit-ups could
00:08:40
potentially maybe give you that six-pack
00:08:42
abs that you're hoping for
00:08:43
it connects from the anterior part of
00:08:45
the pelvis right here
00:08:47
to the costal cartilage of the ribs
00:08:49
right here and pulls those together
00:08:51
which is how it bends the spine so
00:08:52
rectus abdominus flexion of the spine
00:08:55
or bending of the spine laterally to the
00:08:57
rectus abdominus are the external
00:08:59
abdominal
00:09:00
obliques they're called obliques because
00:09:02
they're not parallel or vertical like
00:09:03
this they kind of run a diagonal so we
00:09:05
call those obliques
00:09:06
and the external abdominal obliques do
00:09:08
vary similarly but they can also
00:09:10
contract either one at a time
00:09:11
which can bend you down like this so
00:09:14
it's kind of like doing a sit up but
00:09:16
kind of to the side
00:09:17
they have similar origin insertions
00:09:19
which are the pelvis and the ribs
00:09:20
so we've looked at muscles that control
00:09:22
the elbow joint the shoulder joint
00:09:24
the spine now let's look at the hip
00:09:26
joint the two prime movers here are the
00:09:28
gluteus maximus
00:09:29
the gluteus maximus extends the hip
00:09:31
joint or straightens the hip joint out
00:09:33
it originates on the pelvis and inserts
00:09:36
on the femur
00:09:36
so it's going to bend that femur back or
00:09:38
bend it posteriorly
00:09:40
now the antagonist of the gluteus
00:09:42
maximus we don't see in our diagram
00:09:43
because it's an internal muscle that
00:09:45
muscle is called the iliopsoas it's the
00:09:47
antagonist of the gluteus maximus
00:09:49
whereas the gluteus maximus extends the
00:09:51
hip joint this is going to flex the hip
00:09:53
joint
00:09:54
and here's a picture of that muscle so
00:09:55
you can see a little bit what it looks
00:09:56
like so gluteus maximus
00:09:58
extends the hip joint iliopsoas flexes
00:10:00
the hip joint now we'll look at muscles
00:10:02
that control knee movement
00:10:03
the first one we have is the biceps
00:10:05
femoris not to get confused with the
00:10:07
biceps brachii your biceps femoris are
00:10:09
also called the hamstrings so these are
00:10:10
your back leg muscles
00:10:12
and their job is going to be to flex the
00:10:14
knee joint the biceps femoris or
00:10:16
hamstrings are going to originate in the
00:10:18
pelvis
00:10:19
and the femur and their insertion or the
00:10:21
movement part is the tibia and the
00:10:22
fibula
00:10:23
so they're going to pull on the tibia
00:10:24
and the fibula to cause those to move or
00:10:26
to flex the knee to bend the knee bend
00:10:28
the knee game of thrones reference
00:10:30
probably not i'll edit that out the
00:10:31
antagonists of the hamstrings or biceps
00:10:33
force
00:10:34
are the quadriceps now the quadriceps
00:10:35
are really four muscles
00:10:37
we have the rectus femoris right here
00:10:39
the vastus lateralis down here
00:10:41
the vastus medialis and between those
00:10:43
deep or underneath all of this is the
00:10:45
vastus intermedius
00:10:46
those four muscles make up the
00:10:47
quadriceps or your quads
00:10:49
the quads are in charge of extension of
00:10:51
the knee are straightening your knee
00:10:52
joint back out
00:10:53
and their origin includes the pelvis and
00:10:55
the femur and their insertion is going
00:10:57
to be the patella and the tibia
00:10:58
so they're going to pull up on that
00:11:00
kneecap and the tibia whenever you
00:11:02
straighten out the leg now we've got
00:11:03
another muscle here that maybe doesn't
00:11:04
belong on this list but i think it's a
00:11:06
cool muscle and that's called the
00:11:07
sartorius
00:11:07
the sartorius is actually the longest
00:11:09
muscle in the body and it's going to
00:11:11
connect from the lateral part of the
00:11:12
pelvis right here
00:11:13
down to the medial part of the tibia and
00:11:16
i always think of this as the stinky leg
00:11:17
muscle
00:11:18
if you do the stinky leg you got to use
00:11:19
your sartorius do the stinky leg do the
00:11:21
do the stinky leg is that how it goes
00:11:23
i don't know music so the sartorius will
00:11:25
rotate the knee laterally
00:11:27
if you sit cross-legged you have to use
00:11:28
your sartorius to sit that way
00:11:30
it's a way to get your knees to the side
00:11:32
last but not least let's take a look at
00:11:33
two muscles that control the ankle joint
00:11:35
the first one is the gastrocnemius
00:11:37
and that prefix gastro means stomach and
00:11:40
it has nothing to do with your stomach
00:11:41
except for the fact that
00:11:42
whoever discovered this muscle said hey
00:11:44
this looks kind of like the shape of the
00:11:45
stomach
00:11:46
and now we'll call it gastroenterous
00:11:48
forever the gastrocnemius connects from
00:11:50
the femur
00:11:50
right here down to the calcaneus in the
00:11:53
heel
00:11:54
it's going to pull the heel up which
00:11:56
will extend
00:11:57
the ankle now technically we call this
00:11:59
plantar flexion of the ankle
00:12:01
because it moves the foot in the plantar
00:12:03
direction which is the downward
00:12:04
direction or towards the the base of the
00:12:06
foot but i also like to think about it
00:12:08
as
00:12:08
extending or increasing the angle of the
00:12:11
ankle joint its antagonist is the
00:12:13
tibialis anterior
00:12:14
which is named because it's connected to
00:12:16
the tibia and it's
00:12:18
on the anterior side the tibialis
00:12:20
anterior connects the tibia
00:12:22
up here to the tarsal bones down here
00:12:24
and that's going to pull your foot
00:12:25
upward i think about this as flexion of
00:12:28
the ankle but to be technically accurate
00:12:30
we need to call this dorsal flexion
00:12:32
because it's flexing the ankle toward
00:12:33
the dorsal side or the top side
00:12:35
of the foot so the gastrocnemius does
00:12:37
plantar flexion of the ankle joint and
00:12:39
the tibialis anterior does dorsiflexion
00:12:42
of the ankle joint this has been a lot
00:12:45
let's recap all these muscles
00:12:46
but not worry too much about the origins
00:12:48
and insertions and just focus on where
00:12:50
is the muscle
00:12:51
and what is its movement we have the
00:12:52
biceps brachii which are going to flex
00:12:54
the elbow joint we have the triceps
00:12:56
brachii
00:12:57
which will extend the elbow joint we
00:12:59
have the deltoids which will abduct the
00:13:01
arm or move the arm away from the
00:13:02
midline or raise the arm
00:13:04
we have the pectoralis major which will
00:13:06
rotate the shoulders anterior
00:13:08
and the latissimus dorsi which will
00:13:10
rotate the shoulders posterior and a
00:13:12
little bit down
00:13:13
we have the trapezius which will move
00:13:14
the scapula up and down and rotate the
00:13:16
scapula and all that
00:13:17
we have the rectus abdominus which will
00:13:19
bend the spine like doing a crunch or a
00:13:21
sit-up
00:13:21
and we have the external abdominal
00:13:23
obliques which do the same thing but
00:13:25
it'll help you bend down to one side
00:13:27
or the other we have the gluteus maximus
00:13:29
which will extend
00:13:30
the hip joint or move your leg backward
00:13:33
or posterior
00:13:34
and the antagonist of the gluteus
00:13:35
maximus is the iliopsoas muscle
00:13:37
it's an internal muscle that's going to
00:13:39
be a hip flexor that flexes or bends the
00:13:42
hip muscle
00:13:42
like whenever you kick a ball you're
00:13:44
using your iliopsoas muscle controlling
00:13:46
the knee joint we have the biceps
00:13:47
femoris
00:13:48
which will flex or bend the knee and we
00:13:50
have the quadriceps muscle which will
00:13:52
extend or straighten out the knee
00:13:54
we have the sartorius or the stinky leg
00:13:55
muscle which rotates the knee to the
00:13:57
side
00:13:58
or laterally we have the gastrocnemius
00:14:00
which is going to bend your foot down
00:14:02
or plantar flexion of the foot and we
00:14:04
have the tibialis anterior which will
00:14:06
raise the foot or
00:14:07
dorsiflexion of the foot all right
00:14:09
here's a blank diagram now
00:14:10
take a moment pause the video see if you
00:14:12
can identify all of these 15 muscles
00:14:14
as well as the action of each muscle
00:14:16
what movement does it cause
00:14:19
all right here are those muscles again
00:14:20
so you can check and see how many you
00:14:22
got right
00:14:27
this is going at the end of the video
00:14:34
look like you're gonna be a really big
00:14:39
[Music]
00:14:41
slug
