Lesson video

Welcome to today's lesson.

I'm Mrs. Brooks and today, I'm gonna be talking to you about muscles.

We're gonna be looking at the names of some major muscles, but then we're gonna look at how they work together in pairs and we refer to that as antagonistic pairs.

So this is part of the anatomy and physiology unit, specifically, looking at the musculoskeletal system.

But we're gonna look more at the muscle part of how they work in pairs.

The outcome of today's lesson is that you'll be able to label those major muscles in the human body and then build on that learning to describe how they work as antagonistic pairs to produce movement.

A lot of what we learn about in sport and PE is how the body moves and is able to perform the skills and the actions that are needed in order to be able to be physically active or play sport.

So this dives into that area of what are those muscles doing and how are they working together and collectively to be able to create that movement.

Now a really common pair that everyone refers to at this point is biceps and triceps.

So we know they are located, or you might not know, but they're the two muscles that are located in the upper arm and they work together to help produce movement.

Can you think of any other pairs that you might know about already in the human body? Now our key words for today are really important for us to make sure we feel happy with what they mean because they're all quite similar and therefore can get easily mixed up.

So we will be looking at what an agonist is and that is very much a muscle that creates movement.

The antagonist, look at the similarity there.

It's a very similar word.

We just add that ant before it and that is the muscle that's often working in the opposite way to support the agonist.

We will learn about what a fixator is in order of having a role of stabilizing movement.

Muscles work in pairs.

And we do refer to them as antagonistic pairs.

Often one contracts and one relaxes.

So we've just mentioned to you about the biceps and the triceps.

If I do that now with my elbow, I am flexing it because I'm decreasing the angle at the joint.

The bicep is act as the agonist, so it's contracted.

To support that movement, the triceps has relaxed or lengthened to act as the antagonist.

So we then refer to that as an antagonist pair and we know none of this would be able to happen without tendons and they are that very tough fibrous connective tissue that's at the end of our muscles and attaches to bones.

And when muscles contract, the tendons will pull on that bone to be able to produce movement.

So I've divided the lesson into three areas.

We're gonna first of all look at those muscles in the upper body and talk about their roles.

We'll then replicate that by looking at those muscles in the lower body.

And then once we've got that grounding and that understanding of those key names, we're gonna start looking at how those muscles work together in those antagonistic pairs.

So let's get started and look at the muscles of the upper body.

Now this image here is quite a familiar image when it comes to muscles and there you can see that that person is studying what we know is the anatomical position.

At the minute we can just see the muscles all over the body.

But those really that are in the front of the body, we often refer that to as anterior muscles.

Now the human body is full of those muscles and they are known as voluntary muscles.

So our brain has to work with them in order for them to move.

When they contract, on the whole, they shorten, all right, they largely shorten.

There's the odd occasion where a muscle will contract and lengthen, but for today's learning, we'll just go with the majority is that most of the time when they contract they will shorten.

Now that means that allows us to complete everyday tasks, i.

e.

walking, or those kind of complex movements that we associate with sport.

Now whilst we're looking at that image in that anatomical position, are there any there that you can point out a name that you may already be familiar with? This might be a good opportunity if you've got a post-it note that you write what that muscle is and stick it either on the diagram or on yourself or on someone else to see if you're actually right in terms of what that name is.

I would say at this point if you're worried about spellings, please don't.

But we'll make sure we go through the accuracy of the spellings as we move through the lesson.

Okay, so if we look at the muscles in the upper body first.

We can see now on that diagram we have both the anterior, the front diagram.

We've also got the opposite of that.

We've got the posterior, we've got the muscles in the back of the body, but those that have been shaded are very much those major muscles that we need to be aware about in that upper body in that torso area.

So we've got this big muscle here in the shoulder, which is known as the deltoid.

Then we've got the muscles that exist in the chest, the pectorals.

We have to be very careful as we move through today that we don't use the shortened versions that you may have heard if you're in a gym environment or you've been talking about muscles or learning about this in other areas, all right? And in this instance the people might say delts, they might say pecs, right? We need to make sure that we use the full anatomical term.

We've then got, as already mentioned, those muscles in the upper arm, the front of the upper arm, which are the biceps, that muscle in the back that kind of you can see, it makes almost like a long triangle shape is known as the trapezius.

It starts at the neck and it moves down the center of the back.

We've got the triceps, which we know are our pair with our biceps and they're also in the upper arm, but they're in the back of the upper arm.

And then this big muscle here, latissimus dorsi, which goes either side of the spine in the virtual column.

And again, we really don't want to be saying lats, we wanna be getting used to that word latissimus dorsi.

So let's look at them in a bit more detail each.

And in doing so, try and think about those sporting examples where that muscle is in action.

So we're gonna start with the deltoid, alright? We now know that is in the front and the back of the body.

So in this diagram we can see how it's also in that posterior part of the body and it causes, when it contracts, it causes that abduction of the shoulder joint.

What would you do with your arm if you are abducting the shoulder joint? Absolutely, well done.

If you are doing what I'm doing now and bringing your arms out away from the midline, this kind of center line that runs right down the middle of our body or imaginary line that runs down the middle of the body, you would be moving your limbs away from that and that would be abduction of the shoulder joint.

So we now know that the deltoid is what is causing that movement.

In fact, if you were to do it again and actually have your hand on the deltoid, you would feel significantly that muscle is definitely in that state of contraction.

It is tense and it's actually shortened.

All right, so it's doing the work of causing that movement.

What's a good sporting example of that? Well, there are lots, but this might be a good one to just reference at this point.

We know a lot of goalkeepers, in that position they have to move that arm out to the side to try and save the ball going in the net.

So that's a really good example of the deltoid being used to create that movement.

What about the biceps? What do you think the biceps do? Well actually we saw myself in the introduction quite simply do a flexion of the elbow joint.

Can you think of sporting examples where flexion of the elbow is used and therefore that's our biceps actually in action.

Here's an example.

We can see this rock climber there is gonna use his biceps to be able to pull up now and bring the body upwards and that will cause that flexion of that elbow.

Latissimus dorsi, that big muscle that you can see it almost sits as a V in that diagram.

All right, and that will pull the arm down towards the body.

So if we're in this position here and we were to do this and also if we carried on, we'd eventually get all the way to the bottom.

So we've got that adduction this time, we've got that arm coming down to the midline of the body and it's the latissimus dorsi that's pulling those limbs down and causing that movement in that shoulder joint.

Really good example here of maybe when you're doing that butterfly stroke, such a complex stroke in swimming and uses a lot of those muscles in the upper body.

But as the arms go in the water they have to pull the water before they can come back out.

And that's how you are able to progress and move through the water.

And we refer to that as the pull phase.

So you're pulling the arms through the water and it's the latissimus dorsi that's causing that movement.

So let's have a good check at this point.

So we've looked at quite a few muscles here.

So our first check, we have got an image for you to put into your mind.

So imagine you've got someone who's about to throw or make a chest pass in netball and therefore they'll probably be holding the ball close to their chest or just above in front of their head or maybe over their head.

But which of these muscles will be responsible at the elbow during that preparation phase? Would it be A, the pectorals, B, the biceps, C, the triceps or D, the deltoid? Five seconds to decide.

Well done if you went with biceps and made that link to what we'd already talked about in terms of that flexion of the elbow and the biceps being in contraction to cause that movement.

So let's look at the trapezius.

So we said it was that kind of triangle or that V-shape, a similar V-shape, sorry, but this time at the top of the body as kind of the neck working down to that center of the back.

And that also causes abduction of the shoulder joint.

So often muscles are working together and the trapezius will also do this help within this movement.

So for example, it could be that when you are throwing the discus in athletics, you can see there that athlete has got the arm out to the side and therefore is in the abduction position ready to before to rotate and then release.

The triceps, they cause contraction, sorry, they cause extension of the elbow joint.

So if we think back to our netball athlete that we had in our checkpoint, when that ball is then thrown or pushed forwards, the elbow will straighten, therefore it will cause extension and now the triceps take over and they cause that extension of the elbow joint.

Another example of that is when you are maybe doing a serve in tennis and although you might start with your arm bent, you're gonna straighten it in order to strike the ball.

And finally we've got the pectorals, they cause adduction of the shoulder joints.

So two big circular muscles in the top of the chest there.

And an example of that is if we are looking at maybe a golf swing off the tee shot, and as the arms come down we know that we're gonna get that adduction to be able to strike the ball.

Now in that torso you do also have some muscles in the core as we refer to them.

So you've got your abdominals, again, could be shortened to abs but we need to get into those good habits of saying abdominals.

And you've also got as kind of as we're moving into the lower body but fit within that core area and you've got those gluteals, not glutes, gluteals.

So which of the following is responsible for adduction of the shoulder? Is it A, the pectorals, B, the biceps, C, the triceps or D, deltoid? Well done.

It is in fact the pectorals.

Now our abdominal muscles are very important for posture but they also allow our spine to flex.

So as I bend forward now we are getting some flexion of the spine area and also that kind of flexion of the hip joint.

So an example of that could be very simply like a sit up.

You may have done that, done that movement where you're on the ground and you just bring your upper body up as you sit up and then you go back down, a very common movement to work on those abdominal muscles 'cause it really isolates those muscles 'cause they're the ones that are doing a lot of the work.

If we think about that in a sporting sense, we can see there we've got this person here tucking into that position so they can rotate and hopefully land on that beam.

So the abdominals will have allowed that flexion to occur and that tuck position to be possible.

Now the gluteal, when they contract, they cause hip extension.

So it might be now that I almost get you to all stand up and think about if you were to just put your leg out to the back, maybe keep it straight and I instantly can feel that that muscle in my buttock is the one that's contracting, all right, as I go into that position.

So I've extended the hip and that's been caused by that contraction of the gluteals.

Sporting example we can see there is those athletes are driving out from that sprint start.

We are definitely getting some hip extension certainly in that back leg and that's gonna be those gluteals that will be causing that contraction.

And hence why a lot of sprinters work on that muscle area a significant amount because the more powerful that muscle becomes, the more powerful that hip extension is, which means they're gonna be able to drive out of that block as quickly as possible.

So which of the following is on the anterior, the front of the body.

We've looked at both anterior and posterior diagrams. Which of these is on the front? Well done if you went with C, biceps, it might be that you almost stood yourself in that anatomical position and realized that the other three are all in the posterior in the back of the body but the biceps are the front of the upper arm.

Which brings us nicely onto our first task.

We can see there we've got both our anterior and our posterior diagram with some arrows but we have some muscles that are missing from those arrows.

Pause the recording and label those diagrams. Welcome back.

How did we do? Let's work around from the top left.

Did you get our pectorals, then our biceps, and then our abdominals all in that anterior diagram.

As we move off over to that posterior, we've got the triceps in the back of the upper arm, we've got our trapezius.

Moving onto our deltoid.

We could have labeled that in the front as well.

We do have a front and a rear deltoid.

Latissimus dorsi, that big muscle down the back.

And then finally those gluteals, okay, those big muscles in the buttocks and like we've been saying, we can't say glutes, we've gotta get used to that gluteals.

So let's replicate that now with our learning.

But now look at those muscles in the lower body and outline their roles.

So we can see here we have a big muscle group known as the quadriceps.

They may have been the ones that you referenced earlier when I said are any of the muscles that you can consider 'cause these are a common muscle group that everyone talks about, largely because there are four of them, quad, and they work in that upper thigh area where we've got that big long femur.

In the back of those working opposite to the quadriceps we have the hamstrings, and also in that back of the lower leg we have that gastrocnemius, a really tricky one to spell.

You always wanna try and make sure you put the C in there and that will hopefully help you get that spelling correctly.

But you can see that's a very bulky muscle in the back of the lower leg.

And if you were to stand on your tiptoes now I imagine you would feel or sense that muscle contracting to allow you to do that movement.

Now the hamstrings are the main muscle that will cause flexion of the knee, all right, so we know that's when the knee joint will bend and the angle will decrease.

So for example, look at our athlete here as they are preparing to make that conversion in rugby, we can see that back leg is definitely flexing and that front leg as they're gonna plant that foot is also in a slight state of flexion to be able to stay balanced.

But if we look specifically at that back leg, it will be the hamstrings that are contracting to allow that flexion to take pace.

In contrast, our quadriceps cause extension of the knee.

If you are sat now, I would just get you to pause and just raise up your lower legs or one of them so you would straighten your knee and if you put your hand on your quadricep group, we now know it's in the front of the thigh.

I suspect you will feel that go into a state of tension.

And that's because it's working, it's connected to our tibia, our bone in the lower leg and as it contracts it pulls that bone up and we get that extension of the knee joint.

Can you think of some sporting examples of that? One here is a good one to use, one of many, which is when obviously you execute or you follow your leg throw to strike the ball in football so the knee will then extend and that's very much caused by that contraction of the quadriceps.

With that gastrocnemius, you saw me earlier going onto my toes, all right, so I was pointing my toes and that's flexion of my ankle joint and it's that gastrocnemius that will allow that movement to take place.

We know lots of sports, ballet being one of them, where it's very important that those toes are pointed so that the movement looks aesthetically correct and then might get some high marks from the judges.

And we now know that there's that gastrocnemius that will be allowing that toe to be pointed in that way so that movement looks aesthetically pleasing.

So now we've been introduced to our lower muscles, which of the following is not on the posterior? So not in the back part of the body.

Is it the A, the gluteals, B, the hamstrings, C, the quadriceps, sorry, or D, the gastrocnemius Well done, it is in fact C, the quadriceps, 'cause we learned that they are in the front of our upper thigh.

Now we've got three images here and which of them is responsible for flexion of the knee joint? Do we think it's image A, image B or image C? Well done if you went with B.

Now all those images are in the posterior part of the body, but B is actually showing the hamstrings, which are those in the upper thigh at the back and they're the ones that are responsible for flexion of the knee joint.

Which brings us nicely onto our second task, which will be very similar to what we've done before, but we're now gonna look at those muscles in the lower body.

On our diagram, can you label the gastrocnemius, the gluteals, the hamstrings and the quadriceps? Pause the recording and come back to me when you're ready.

Welcome back.

Did we, if we start on our anterior diagram, where did we get our quadriceps? At the front of the thigh, our gluteals in the buttocks, our hamstrings at the back of the upper thigh.

And finally the gastrocnemius, which is that muscle in the lower leg at the back.

Now we know our key names for the muscles in both the upper and the lower body.

We're gonna finish off the lesson by looking at how those muscles work together in antagonistic pairs.

And we need to be able to add our explanations to that.

Now what you're seeing on that image there is the bicep muscle.

Just look closely at the blue parts, the blue ends, they're trying to show you the tendon and how those two tendons are connected to bones.

If we look specifically at that lower tendon, that's connected to our radius.

So when that muscle will contract, it will often shorten and it will pull on that bone to cause movement.

All right? And muscles can only pull, they can't push.

So your body is designed for that to be the case.

And what you get from that, when those tendons do that role is that shortening results in that movement of the joint.

So just like we did earlier, we then get the tendon pulling on the radius to bring it upwards and cause that flexion.

Now, they have to team up, they have to work collaboratively for this to work, 'cause remember where our bicep sits, we now know we've got a tricep right behind it in the same part of the body.

So what happens is when one contracts, the other one will also be working and supporting that movement.

Now in this instance, the bicep is the one that's doing most of the movement.

So we refer to that as the agonist.

Sometimes you might hear people refer to that as the prime mover.

The muscles that react relaxes.

So in this instance, the triceps, that's relaxing, and it's in slight opposition to be able for that movement to occur, so we refer to that as the antagonist.

Now what do you think will happen as I then reverse that movement? So if I now straighten the elbow, what's happened to our antagonistic pairs? What we've also got at that point, whether it's flexion or extension, is we have a fixator.

Now a fixator muscle is often one that we don't really see is moving, but we know it's working in some way 'cause it's gonna stabilize the joint.

So remember we've kind of got two joints in operation here.

We've got the one that's doing the movement, we've also got this joint here.

It's not really moving as such, but it's in the same area of the body.

So basically the deltoid, this muscle at the top of the shoulder, really big muscle.

Now I know, now I'm in that position, not only have I got my biceps working, but I can sense that my deltoid is doing something and that means it's stabilizing.

So it's holding the shoulder joint to make sure that the bicep can do its key role, which was to pull on that radius and cause that movement.

Now, if we've got, if I did have a weight in my hand now, I would be kind of doing bicep curls.

I could be doing it in one hand or I could be doing it in both hands, all right? So you now know, or we now know that when I've got, when I'm bringing the weight upwards, we've got flexion and therefore the biceps are the agonist.

Meanwhile the triceps are the antagonist and they're relaxing in that opposition.

And when I asked you earlier, did you work out that the roles reverse on the way down? So whether it's this way or I have got my weights in my hands now and I'm then gonna lower them, what happens now is I've got extension of the elbow joint and the triceps now act as the agonist and the biceps become the antagonist.

So they've basically just swapped over as the movement reverses.

So let's just make sure we feel comfortable with that in the upward phase of the biceps curl.

So this was me bringing my weights up to here.

Which of the muscle is working as the antagonist? Is it A, the biceps B, the triceps, or C, the deltoid? Well done, it is in fact the triceps.

This is a really good question to look at because it can be quite easily looked at and you think it's saying agonist, so we need to make sure we read it carefully and see in this instance it's the antagonist, so therefore it's the muscle that is in opposition or is supporting the agonist as it does its main work.

Let's look at a different example.

So when we kick a ball, the quadriceps act as the agonist when extending the knee joint.

So if we know the quadriceps is the agonist, which muscle do you think is the antagonist? That's right, it's the hamstrings, 'cause they're both in the same area of the body in that upper thigh.

So as the quadriceps is doing its work, it will be contracting, the hamstrings will be lengthening slightly or relaxing to allow that movement to take place.

On the way down, or if you then flex it, flex the knee, sorry, or bring the knee back down, the roles are gonna reverse in the same way they did on the bicep curl.

So let's look at this checkpoint.

And we've got three examples there of movement.

We've got A, someone holding a barbell in a front position as they do a squat.

We've got B, an athlete that is starting with the ball and then he is gonna push it forward to a teammate as a chest pass.

And then we've got someone that's lifting that knee, that leg, sorry, upwards.

Which of the following is an example of the triceps acting as an agonist? Is it A, B or C? Really well done if you picked out B, that chest pass movement and hopefully you worked out that that's extension of the elbow as that ball is pushed forward and we now know that triceps act as the agonist when the elbow extends.

So that is a nice lead onto our final task.

What I would like you to do is we have just one movement here and it's a sprinter that's accelerating out of the blocks.

We need to feel confident in being able to explain how antagonistic pairs work.

So could you do that, explain them, and then identify at least six major muscles and how they're working together in that way to allow that movement to occur for our sprinter.

Pause the recording and come back to me when you're ready.

Welcome back.

So for the first part of the task, as part of your explanation, you could have written something along the lines of the agonist contracting to create the movement.

And then in contrast to that, the antagonist relaxing.

So that movement can occur and we know that is referred to as antagonistic pairs.

So if we look at our sprinter, you could have worked out, if we look at the arms, first of all, so in the right arm you've got the biceps that are causing flexion of the elbow, whereas that back arm, the left arm is extending.

So that would've been the triceps that are creating that movement.

In that front knee you've got the hamstrings that will be flexing the knee, whereas in the back leg you've got extensions.

So that will be the quadriceps acting as the agonist.

The gluteals, remember that big muscle group in the buttocks, they'll be extending that hip at the back, that back leg.

The right pectorals, okay? That arm or that shoulder is adducted.

So it's close to the upper body as they drive out the blocks.

And then the left deltoid, the arm at the back, that will be just away from the body slightly.

So there will be some abduction and that can be caused by the deltoid.

So in summary, we've learned a lot in today's lesson.

We now know in the major muscles and the names of them and how they will all contract to produce the movement throughout the body.

We know that's not possible without that attachment of our tendons.

And we've then gone on to learn that they work together in pairs and that often means one is contracting whilst the other is relaxing.

The muscle that's contracting is often the agonist or the prime mover, whereas the one relaxing is referenced as the antagonist.

And we also learn that to create that stability at a joint and make sure that movement is nice and efficient and smooth, we also have a fixator muscle.

Some examples of antagonist pairs and there are more, but we really dived into some examples of where the biceps and triceps are working together and in the upper body and likewise in the lower body when the quadriceps and the hamstrings are also working as an antagonistic pair.

I've really enjoyed taking you through muscles and how they work to produce movement.

Thank you for joining me, and I really look forward to seeing you on the next lesson.