Rotator cuff muscles
Summary
TLDRThis script delves into the intricacies of the shoulder's rotator cuff muscles, crucial for swimmers and athletes. It highlights the role of these muscles in securing the humeral head within the glenoid fossa, enabling a wide range of motion. The video explores the functions of the four rotator cuff muscles—supraspinatus, infraspinatus, teres minor, and subscapularis—discussing their attachments, nerve supply, and impact on shoulder stability and movement. It also touches on common injuries and offers exercises to strengthen these muscles, emphasizing the importance of maintaining shoulder health for those with physically demanding activities.
Takeaways
- 🏊♂️ The script discusses the importance of shoulder muscles, especially for swimmers, in providing power and stroke length.
- 🤔 The focus is on the rotator cuff muscles, which are crucial for securing the humeral head within the glenoid fossa and preventing shoulder injuries.
- 💪 There are six scapular humeral muscles, including the deltoid and teres major, which are not part of the rotator cuff but play a role in shoulder movement.
- 🔍 The rotator cuff muscles include supraspinatus, infraspinatus, teres minor, and subscapularis, which are essential for supporting the shoulder joint.
- 🏋️♀️ The supraspinatus muscle initiates the abduction of the upper limb, followed by the deltoid and trapezius muscles.
- 🔄 The rotator cuff muscles are responsible for both medial and lateral rotation of the humerus, with specific muscles contributing to each movement.
- 🚫 The rotator cuff muscles do not contribute to the adduction of the humerus, which is handled by other muscles like latissimus dorsi.
- 🤕 Overuse injuries are common in the rotator cuff muscles due to their small size and the large range of motion they support.
- 🏥 The supraspinatus tendon can become inflamed, leading to issues like tendonitis, especially when passing through the narrow space under the acromion.
- 💡 Strengthening the rotator cuff muscles is essential for those who use their shoulders extensively, such as swimmers, and can be done using light resistance like elastic bands.
Q & A
What is the main purpose of the rotator cuff muscles in the shoulder?
-The primary function of the rotator cuff muscles is to support the humeral head within the glenoid fossa, maintaining the shoulder joint's integrity and stability.
How many muscles form the rotator cuff, and what are their names?
-There are four muscles that form the rotator cuff: supraspinatus, infraspinatus, teres minor, and subscapularis.
Why are the rotator cuff muscles prone to overuse injuries?
-The rotator cuff muscles are prone to overuse injuries because they have to pass across a small space, which can lead to inflammation and tendonitis, especially due to their critical role in stabilizing the shoulder joint.
What is the role of the deltoid muscle in the shoulder joint?
-The deltoid muscle plays a significant role in holding the humerus into the joint, aiding in abduction, flexion, extension, medial rotation, and lateral rotation of the humerus.
How does the supraspinatus muscle contribute to the movement of the arm?
-The supraspinatus muscle initiates the abduction of the upper limb, allowing the arm to move away from the body.
What is the difference between the teres major and teres minor muscles in terms of their function and innervation?
-Teres major is a medial rotator of the humerus and is innervated by the lower subscapular nerve, while teres minor is a lateral rotator and is innervated by the axillary nerve.
Which nerve innervates the infraspinatus and supraspinatus muscles?
-Both the infraspinatus and supraspinatus muscles are innervated by the suprascapular nerve.
What is the function of the subscapularis muscle in the shoulder joint?
-The subscapularis muscle, located anteriorly, contributes to medial rotation of the humerus, and its main function is to hold the humeral head in place within the glenoid fossa.
How can one strengthen the rotator cuff muscles?
-Strengthening the rotator cuff muscles can be achieved through exercises using elastic bands, focusing on medial and lateral rotation movements to engage the respective muscles effectively.
What is the significance of the brachial plexus in relation to the shoulder muscles discussed in the script?
-The brachial plexus is significant as it provides the nerves that innervate the shoulder muscles discussed, including the suprascapular, axillary, and subscapular nerves.
Why is it important to maintain good shoulder posture and muscle strength for individuals who use their shoulders frequently?
-Maintaining good shoulder posture and muscle strength is crucial for individuals who frequently use their shoulders to prevent joint and muscle damage, ensuring effective use of the rotator cuff muscles and overall shoulder joint health.
Outlines
🏊♂️ Swimming and Shoulder Muscles
The speaker discusses their training phase as a bass, highlighting the fatigue and an upcoming test race. They emphasize the importance of the shoulder muscles, particularly the rotator cuff muscles, which support the humeral head within the glenoid fossa. The speaker mentions the need for secure joint movement and the potential for overuse injuries in these muscles. They plan to explore the rotator cuff muscles in a lab setting, using a model to demonstrate the muscles' roles in abduction, flexion, extension, and rotation of the humerus.
💪 Deeper Look at Rotator Cuff Muscles
The speaker removes the deltoid muscle from the model to reveal the rotator cuff muscles, which are crucial for shoulder stability and movement. They identify the supraspinatus, infraspinatus, teres minor, and teres major muscles, explaining their roles in medial and lateral rotation of the humerus. The speaker also discusses the innervation of these muscles, noting that supraspinatus and infraspinatus are innervated by the suprascapular nerve, while teres minor and deltoid are innervated by the axillary nerve. The teres major is innervated by the subscapularis nerve, which is also connected to the subscapularis muscle.
🤔 Understanding Muscle Functions and Injuries
The speaker delves into the functions of the rotator cuff muscles, focusing on their role in stabilizing the humerus within the glenohumeral joint. They explain that these muscles are not involved in adduction but are essential for maintaining joint integrity. The speaker also discusses the potential for overuse injuries, particularly tendonitis, due to the muscles' location and function. They highlight the importance of strong rotator cuff muscles for those who frequently use their shoulders, such as swimmers, and suggest exercises using elastic bands to strengthen these muscles.
🏋️♂️ Strengthening the Rotator Cuff
The speaker concludes by emphasizing the importance of maintaining strong rotator cuff muscles, especially for those who engage in activities that heavily utilize the shoulders. They describe exercises that can be performed using elastic bands to strengthen these muscles, focusing on medial and lateral rotations of the humerus. The speaker also mentions the innervation of the rotator cuff muscles by the brachial plexus, which is crucial for their function. They look forward to discussing more about the shoulder in the next session, promising to cover topics such as the shoulder's baring.
Mindmap
Keywords
💡Bass training
💡Fatigue level
💡Test race
💡Shoulder mobility
💡Humeral head
💡Rotator cuff muscles
💡Scapular humeral muscles
💡Supraspinatus
💡Infraspinatus
💡Teres minor and major
💡Subscapularis
💡Brachial plexus
Highlights
The importance of shoulder muscles in swimming and other activities that require a lot of shoulder movement.
Discussion of the big muscles of the shoulder and their role in providing maximum power and a long stroke in swimming.
The role of the humeral head in securing and holding the shoulder joint, and the importance of its stability.
Introduction to the six scapular humeral muscles, including the deltoid and teres major.
The main job of the rotator cuff muscles is to support the humeral head within the glenoid fossa.
The rotator cuff muscles are prone to overuse injuries due to their small size and large job in stabilizing the shoulder.
The lab session focuses on the rotator cuff muscles of the shoulder, highlighting their importance in maintaining shoulder stability.
The use of a model to demonstrate the muscles and their functions, including the deltoid and its role in holding the humerus into the joint.
The role of the supraspinatus muscle in starting the abduction of the upper limb.
The infraspinatus muscle's role in lateral rotation of the humerus.
The teres minor muscle's contribution to lateral rotation, contrasting with teres major's medial rotation.
The subscapularis muscle's role in medial rotation and its deep position beneath the scapula.
The different innervation of the rotator cuff muscles, with supraspinatus and infraspinatus being innervated by the suprascapular nerve.
The importance of the rotator cuff muscles in holding the humerus in place and their role in the glenohumeral joint.
The practical application of strengthening the rotator cuff muscles using elastic bands for exercises.
The explanation of how the rotator cuff muscles contribute to the stability and function of the shoulder joint.
The summary of the rotator cuff muscles' functions, including their role in rotation and stabilization of the humerus.
Transcripts
so I'm reaching the end in my bass
training phase fatigue level high and
racing this weekend as well which is the
test race early season to see how things
go but I've just been swimming in the
pool again at lunchtime my usual daily
swim and thinking more about the
shoulder so we looked at the big muscles
of the shoulder last week and of course
I think about the big muscles a lot when
I'm swimming and how I'm gonna use those
muscles to get maximum power and get a
nice long stroke and move myself and
that sort of thing but something that's
also really important to swimmers and
other people who use their shoulders a
lot is not just the wide range of
mobility that we have but how is the
humeral head secured and held within
that joint because it's it's quite an
open face which is great means you've
got a wide range of movement but you
need to hold that humerus securely there
are six scapular humeral muscles we
talked about a couple last week deltoid
and we talked about teres major but the
other four which come up all the time of
the rotator cuff muscles so the rotator
cuff muscles their main job is to
support the humeral head within that
glenoid fossa and to keep that shoulder
together and those muscles are
reasonably big but they have to pass
across a small space and they get rather
small and tenderness and a number of
people will have problems with their
rotator cuff muscles because this more
and they've got quite a big job to do
and they suffer from overuse injuries
and that sort of thing so let's go in
the lab I'll take a break from marking
exam papers let's go to the lab and talk
about the rotator cuff muscles of the
shoulder briefly all right let's go all
right then we can use this guy no
photography unless you're me I can do
that no food and drink I can't do food
and drink either
we'll use you but I've also got a very
nice upper limb model move so I I really
like this model this is another one of
Rudy's models these are beautifully made
and this is kind of kind of a rubberized
plastic some bits are harder than others
I would love more models like this I'd
love a lower limb model like this as
well just to show musculoskeletal stuff
but it'd be nice if the muscles were
nice and stretchy and this one it seems
like maybe it's got a little bit harder
over time but it is prone to falling
apart when you touch it I think puts
students off a little bit and it needs
to be able to pain putting back together
but then that's all part of the learning
process right which is why we have a bit
left over here so we were looking on the
the model last week of the of the large
muscles of the shoulder region that tend
to act on the upper limb and move the
humerus and what have you and we looked
at deltoids and here's the deltoid
muscle so I say there are there are six
scapula humeral muscles so summing that
is to say six muscles passing between
the scapula and the humerus and we
looked at the deltoid we talked about
how the deltoid holds the humerus into
the joint into the infra glenohumeral
joints when you're carrying something
heavy the the weight is carried from the
hto skeleton through trapezius and other
muscle through the scapula and then from
the scapula and the clavicle down to the
humerus and everything's held together
right and that's one of the roles of the
deltoid muscle
now I mentioned supraspinatus so
superspinatus as I said start off the
abduction of the upper limb and then the
deltoid muscle can take over and then
trapezius takes over to rotate the
scapula do you remember and I mentioned
that the deltoid muscle can also do
flexion and extension of the humerus at
the glenohumeral joint what I probably
didn't mention is about row
right we also have medial rotation and
lateral rotation so if you think about
it this is the humerus that's rotating
here at the glenohumeral joint right yes
the humerus is rotating like this so so
this is what we've got so this is medial
rotation and this is lateral rotation
and you can see how the the humerus is
rotating here so it's rotating inwards
and outwards now most of that is
occurring up here and these multi penny
fibers of the deltoid muscle can
contribute to this you can imagine how
the anterior muscles can pull this way
so they can add they can contribute to
the medial rotation and how these
posterior fibers here you can pull the
other way and contribute to lateral
rotation but there are some deeper
muscles when we take off the deltoid
muscle then we'll see the rotator cuff
muscles and supraspinatus is one of them
so we take off deltoid the other always
heavier than the other muscle that we
talked about was teres major here so
terror is major we said runs from the
scapula to the humerus then can you see
how this is a right upper limb so
there's the thumb so this is it this is
a right upper limb and can you see how
his teres major here and I said the
teres major is forming the posterior
border of the axilla right under here
but do you see how it's running from the
scapula but then it's running
to the anterior part of the humerus let
me take off bicep so you can see a
little bit more easily no you see I was
running to the anterior part of humerus
that means that if this muscle contracts
it's going to pull the humerus this way
isn't it so teres major then is also a
medial rotator of the humerus
so deltoid and teres major our muscles
linking the scapula and the humerus but
they're not rotator cuff muscles the
rotator cuff muscles are deeper or
closer to the glenohumeral joint and
they they have another function and
there are four of those so we see one
here two up here and then three and
there's a fourth here but it's actually
difficult to separate these two muscles
so here is supraspinatus now this is the
scapula and this is the spine of the
scapula here turn you around so that
matches so here's his right arm here's
the scapula here's the spine of the
scapula here so this this fossa this
groove here is filled with supraspinatus
but there's a hole through here so
supraspinatus is attached to the scapula
superior to this this spine here
but then the tendon passes through this
gap this is the acromion like the
highest part the acromion akropolis the
highest part of the scapula the bit you
have the bony bit you can feel up here
it passes underneath there and inserts
into the humerus and this is this can
know this muscle then is able to pull on
the humerus up here and that starts off
abduction of the humerus right which is
why I say supraspinatus then deltoid and
then trapezius
because this because of overuse injuries
with the shoulder if this tendon gets
inflamed is passing through a fire a
fairly small gap so they in flames it
swells it gets even more annoyed and we
tend to have a bit of a problem him and
some people get tendonitis of that
attendant so if that supraspinatus up
here and this is the spine
then what's this muscle here
infraspinatus very good well done so
yeah this is infraspinatus inferior to
the spine of the scapula and you can see
again how this is passing out also to
the head of the humerus here right now
as we are posterior if you if you
shorten this muscle then what's going to
happen to the humerus all right so the
muscles running across here to the
humerus here it's going to cause lateral
rotation yeah so if they're not if
infraspinatus contracts it's going to
pull the humerus around this way and
it's going to cause lateral rotation now
the muscle down here if this is teres
major this muscle here is teres minor it
is difficult to tell the two apart when
you're dissecting you can separate the
two muscles they are distinct muscles
good to start with they look like one
single muscle but this is teres minor
here so this is also running from the
scapula to the humerus around here so
terror is minor then if you can track
that muscle is also going to give
lateral rotation so teres minor will
give lateral rotation the teres major
here because it passes to the other side
will do the opposite will do the medial
rotation tricky huh the other thing
about these two muscles is they have
different innovation supraspinatus and
infraspinatus are both innovated by the
suprascapular nerve but teres minor is
innervated by the auxilary nerve the
same nerve innervates the deltoid muscle
confused
the teres major is innervated by the
subscapular to have we're making it
worse my probably sorry so these two
muscles are innervated by the
suprascapular nerve
whereas this muscle is innervated by the
axillary nerve which shows that these
two muscles are the separate things
where they're two muscles they have
separate connective tissue surrounding
them and they have different innovation
all of those nerves by the way come from
the brachial plexus which of course is
very nearby because it's running through
the eggs illa so there's supraspinatus
infraspinatus and teres minor their
fourth and final muscle of the rotator
cuff group is this muscle here this is
subscapularis so if I turn the skeleton
around as well we're now looking at this
scapula here right so this muscle is is
underneath here all right so I'm not
sold underneath there which is tricky in
it so it sits between the ribs and the
scapula right so this is subscapularis
is deep to the scapula you can see how
it's running from the deep surface of
the scapula again to the humerus and
it's inserting here now I took the
biceps brachii muscle off but you can
see well you can see how where that
attach is therefore tape yeah so we take
biceps off and you can see this is deep
the biceps there's the long head there's
the short head that means that the long
head is running through this groove here
this means that these fibers are in 13
so the lesser tubercle up here and this
medial edge of the bicipital groove here
so if the fibers are running this way
and they put on the humerus what's going
to happen it's going to give medial
rotation so subscapularis anteriorly
will give medial rotation
and the other guys post eerily will give
lateral rotation and superspinatus will
give abduction so here's triceps so
we're looking at the posterior arm tur
here's the spine of the scapula here's
the clavicle up here here's
supraspinatus running through there
there's the acromion of the scapula
there so supraspinatus is running
inferior to that and inserting to the
humerus up here here is infraspinatus
and here is teres minor here and there
is teres major these tendons are all
inserting into different facets of the
greater tubercle of the humerus up here
so here's the head of the humerus here
here's that bicep it'll groove third
subscapularis inserting here here's
supraspinatus the infraspinatus and
there's teres minor okay so those are
the muscles those are their attachments
and those are the movements that they
can perform but the most important
function is that they're holding the
humerus in place they're holding the
humerus into the glenohumeral joint and
into the scapula and the the fibers of
the tendons actually merge and blend and
support the connective tissues of the
glenohumeral joint of the snow of your
capsule and we'll have you so they're
forming the structure of the joint their
tone keeps the head of the humerus into
the scapula so if one of these muscles
is damaged then that going to reduce the
strength and the function and the
effectiveness of this joint also because
these fibers are inserting so high up
into the humerus they're not involved in
adduction of the humerus so if if we
talk about abduction like this these
rotator cuff muscles are not going to
bring the humerus
back to the body because there and
they're pulling on the head they pull on
the head they're just pulling the
humerus back into the glenohumeral joint
right for adduction for using you know
latissimus dorsi and all these other
guys right that we talked about in the
last video so the rotator cuff muscles
can rotate the humerus and more
importantly they're holding this whole
joint together so it's important that
you have strong rotator cuff muscles
particularly if you're using your
shoulders a lot and it's important to
you know keep your shoulders in a good
position so that you're using with your
rotator cuff muscles effectively if your
shoulders you know start to get pulled
forward and you you're performing strong
movements and you'd like you to damage
the joint and damage the muscles you you
can strengthen your rotator cuff muscles
very simply you don't tend to need to
use a lot of weight things use elastic
bands right so as you hop on to this and
then you do you keep your arm nice and
straight and square and against the
force you do medial rotations you just
rotating the humerus and then yeah you
can feel nice little burn anteriorly
so you get so again subscapularis here
army we've medial rotation if you put
the hand the other way and then you're
pulling in the other direction so you
see how the humerus there is rotating so
then with lateral rotation exercises
we're hitting the posterior muscles I
can really feel that there we're using
infraspinatus and teres minor and that's
how you keep your rotator cuff strong
something like that anyway okay so there
are six muscles linking the scapula and
the humerus four muscles form the
rotator cuff the muscles of the rotator
cuff inserts high into the head of the
humerus so they can rotate the humerus
but their most important function is
holding the head of the humerus into the
glenoid fossa into the glenoid cavity
and hold that glenohumeral joint
together subscapularis is innervated by
the upper and lower subscapular nerves
supraspinatus and infraspinatus are
innervated by the suprascapular nerve
teres minor is innervated by the
axillary nerve as is the deltoid muscle
teres major is also innovated by the
lower subscapular nerve and those are
all branches of the brachial plexus
unsurprisingly because it's running
through the axilla okay so that's the
that's the rotator cuff and those are
the deep muscles of the shoulder make
sure you can identify them
make sure you remember how they insert
into the humeral head and then you'll
hopefully remember which way they rotate
the humerus all right what we'll do next
week it's plenty of stuff doing the
shoulder maybe I'll still be
enthusiastic about the shoulder we'll
find some males talk baring the shoulder
okay thank you very much see you next
time
you
[Music]
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