Lesson video

Hello and welcome to today's lesson.

My name is Mr. Wheate, and I am looking forward to teaching you today.

We are going to be looking at muscles and how they work in antagonistic pairs.

We'll be naming and locating the major muscles of the human body before discussing why they pair up, so that one muscle creates one movement, for example, flexion of the elbow using the biceps, and then its partner in crime, the triceps, creates the opposite movement of extension at the elbow.

Today's lesson is called Muscles and Antagonistic Pairs, and it comes from the Anatomy and Physiology, the Musculoskeletal System Unit.

(mouse clicking) By the end of this lesson, you'll be able to identify all the major bones of the upper body, the core, and the lower body, as well as being able to explain how muscles work in antagonistic pairs.

So, I've already mentioned that the biceps and triceps work closely together to create opposite movements.

I wonder if you can think of and name any other pairs of muscles and point out where they are and what they do in the human body.

The keywords for today's lesson are agonist or prime mover, antagonist, fixator, antagonistic pairs, and tendons.

You may want to pause the video to make a note of them, but I will explain them fully as we come across them in the lesson.

So, in our lesson today, we will first of all locate, name, and describe the role of the major upper body muscles.

In fact, that section will also cover off muscles around the core, like the abdominals, and then we will repeat the process for the major muscles in the lower body.

It is not necessary to learn every single muscle, and if you stay on to do A-level PE or study sports science at university, you will certainly learn some more muscle and muscle names.

But we will cover off the most important ones that operate across the elbow, shoulder, hip, and knee joints.

We will then explore how muscles work in antagonistic pairs and what that really means.

I hope you are ready.

Let's get started.

As you know, the human body is covered in skeletal muscles, which are under our voluntary control.

When instructed by our brains, these muscles contract and shorten, which enables us to move in a wide variety of ways.

So, this allows us to complete everyday tasks and also to perform complex movements in sport.

Can you point out and name any of the muscles on this diagram? Let's look at some of these muscles in the upper body then.

The deltoid is responsible for arm abduction.

So, it's up here on the top of the shoulder where we move the arm up sideways away from the body.

A sporting example of this is a goalkeeper reaching out to the side to save a shot in the corner of the net.

The pectorals are responsible for adduction.

So, putting that shoulder joint and the arm back down towards your side.

A sporting example of this is the start of the forehand swing in tennis.

So, that movement there.

Or a golf swing and is also essential in the bench press when weightlifting, and that's why we see quite often when people are doing their fitness training they'll go and work on their pectorals by doing the bench press.

The biceps, as I mentioned earlier, are probably the most well-known muscle in the body.

When they contract, we flex the arm at the elbow, and a sporting example of this is when pulling the body up when rock climbing or preparing to take a set shot in basketball.

The trapezius is a large, diamond shaped muscle spanning between our shoulders.

It helps with general posture and to abduct the shoulder joint.

A sporting example of the trapezius in action is when throwing a discus in athletics.

The triceps, as we mentioned earlier, they're responsible for extension at the elbow joint.

A sporting example of that is when executing the serve in tennis or a set shot in basketball.

And then finally, the latissimus dorsi stretches around your back, so it's here underneath the armpits, and its function is to pull the arm down towards the body in adduction.

A sporting example of this is during the pull phase of freestyle and butterfly in swimming, and this is why many swimmers have that very triangular profile from behind because they've got that wide or narrow waist and wide shoulders that are built out from the latissimus dorsi.

Let's explore those muscles in a little more detail.

So, the deltoid is responsible for arm abduction, where we move the arm up sideways away from the body.

You can see here we've got the deltoid all over the top of the shoulder, and a sporting example of that is the goalkeeper reaching out to the side to save a shot in the corner of the net.

The biceps contract and flex the arm at the elbow.

You can see them here on the inside of the arm, and a sporting example of this is you can see that rock climber there.

As that person pulls themselves up on the rock, you can tell that the biceps will be contracting, or if I prepare to take a set shot in basketball, I'm in that bicep flexed position.

The latissimus dorsi stretches around your back under your armpits and functions to pull the arms down towards the body in adduction.

A sporting example of this, as I said, is during the pull phase of a freestyle, or like this picture shows the butterfly stroke in swimming.

Okay, let's have a quick check.

Which of the following is responsible during the preparation phase of a chess pass in netball? That's right, it's the biceps.

The trapezius is that large diamond-shaped muscle spanning between our shoulders at the top here.

It helps with general posture and to abduct the shoulder joint.

A sporting example of the trapezius in action is when throwing a discus in athletics.

You can see here that rotational movement.

The triceps are responsible for extension at the elbow joint.

You can see it there on the back of the arm, and it's actually made up of three muscles, which is why it's called the triceps.

Whereas the biceps is made up of two muscles.

I for biceps and two muscles.

Back to the triceps.

A sporting example of this is when executing a serve in tennis or, as I said earlier, that set shot in basketball.

The pectorals or pecs, but don't write that in your exam because you won't get the mark for just writing pecs in the same way you wouldn't get the mark for writing abs or glutes.

You've got to write the full anatomical name.

So, the pectorals are responsible for adduction of the shoulder joint and bringing the arm back down towards your side.

A sporting example of this is the start of a forehand swing in tennis, or, as you can see here, a golf swing.

Next up muscles in our core area around the middle of the body and essential for good posture, among other things.

So, the abdominals are responsible for flexion at the spine and at the hip joint.

A sporting example of this is when tucking to perform a somersault or a forward roll in gymnastics.

And then on the reverse side we've got the gluteals, which are responsible for hip extension.

A sporting example of this is exploding out of the blocks in a 100-meter race.

You also have some other muscles each side of the abdominals called the obliques, and then we've got the hip flexors that run down the front on top of the quadriceps as well, which help with hip flexion.

But they're beyond the scope of the GCSE PE course and something you'll learn more about if you study on to A level.

Let's have another quick check.

Which of the following is responsible for adduction so movement back together at the shoulder joint? Hopefully, you selected the pectorals so the pecs you can feel them contracting here as I pull my arm down.

Whereas it's the deltoid that causes the abduction as it's pulling the arm up to the side.

Again, let's look at those muscles and sporting examples in a little bit more detail.

So, we've got the abdominals here, and contraction of the abdominals causes flexion.

We can feel that flexion at the spine and at the hip joint.

A sporting example of that being when you tuck to perform a somersault or forward roll in gymnastics.

And then around at the back we've got the gluteals, and they're responsible for hip extension.

A sporting example of that is as we explode out of the blocks in a 100-meter race.

We can see there in the picture the glutes or gluteals will be contracting maximally when they do that.

And I guess it's important to note that the gluteals are actually a group of muscles, and then the biggest of those is called the gluteus maximus, and you may have heard of that before.

And probably more a lower body muscle than an upper body muscle because it's operating over the hip joint.

But I've covered it here alongside the abdominals because it causes the opposite movement.

Let's have another check.

Which of the following is on the anterior, which is a posh word for front, side of the body? Is it the latissimus dorsi, the trapezius, the biceps, or the triceps? That's right, it's the biceps.

They're the only muscle that's on the front of the body.

Whereas we've got the trapezius, latissimus dorsi, and triceps on the posterior or back side of the body.

So, what I would like you to do now is label this diagram to identify the muscles you can see from the list on the right.

If you want to add sporting examples of that muscle in action, then feel free.

Pause the video now and come back to me when you are ready.

Let's check what you came up with.

So, the pectorals at the top there.

Underneath that, we've got the biceps, the top of the arm.

Then the bottom one there is the abdominals, or the six pack.

Then, as we're moving over to the posterior or rear view, we can see the triceps in the back of the upper arm.

The trapezius, that triangle shaped or muscle at the top just underneath the neck.

Then we've got the deltoids sitting on top of the shoulder.

The latissimus dorsi stretching around underneath the armpits almost like a v-shape.

And the gluteals, the biggest of which is called the gluteus maximus.

Okay, let's move on to the rest of the muscles in the lower body.

Remembering that the abdominals and the gluteals initiate movements at the hip joint as well.

So, we can see here labelled at the top of the thigh we've got the quadriceps, and that's the muscle that's responsible for extension at the knee joint.

So, straightening of the knee joint.

Sporting example of that is the kicking the ball in football.

Then around the back or posterior side we've got the hamstring, which is responsible for flexion at the knee joint.

Sporting example of that preparing to kick that football.

And then the gastrocnemius is responsible for pointing the toes or plantar flexion at the ankle joint.

Sporting example of that being on point or up on your tiptoes in ballet.

Again, let's look at each of those muscles in a bit more detail.

So, the hamstrings there they're responsible for flexion at the knee joint.

A sporting example of this is preparing to kick a conversion in rugby.

You can see there the left leg of this performer is right back behind him.

So, a fully flexed knee joint using the hamstring muscle.

The quadriceps are responsible for extension at the knee joint.

So, they're around the front here.

And a sporting example of them is the follow through of kicking a ball in football.

So, this striker here, as they're taking a penalty, you can see that leg, the right leg, out in front thanks to the quadricep muscle that are extending the knee joint.

They'll also have the abdominals contracting at that moment to help flex the hip joint.

The gastrocnemius is responsible for pointing the toes or flexion at the ankle joint.

It's actually called plantar flexion, but flexion is good enough for now.

We actually have another muscle in the front of our shin that causes the opposite movement to this, which is called dorsiflexion, and that muscle is called the tibialis anterior as it's on the front.

So anterior of the tibia.

But don't worry, you don't need to remember that muscle for your exam as we focus on the elbow, shoulder, hip, and knee joints for OCR.

So, a sporting example of the gastrocnemius contracting is being on point or on tiptoes in ballet.

Let's check which of the following is not on the posterior or backside of the body.

Is it the gluteals, the hamstring, the quadriceps, or the gastrocnemius? That's right, it's the quadriceps, because those are the muscles that are on the front of our thigh.

And another check which of the following is responsible for flexion at the knee joint.

So, the muscle that causes that bending at the knee joint.

It's the one in the middle there it's B.

So, there are hamstrings, and they cause flexion at the knee joint.

Okay, for the second task, I want you to return to your diagram and add these additional four muscles.

Again, provide a sporting example of it in action if you want.

Pause the video and come back to me when you are ready.

Hopefully, that was a fairly straightforward task for you.

The group of four muscles that make up the quadriceps are on the front of the thigh.

The gluteals are that big group of muscles on your bum that extend the hip joint.

The biggest of which is called the gluteus maximus.

Be careful not just to call them the glutes.

The hamstring group, which is actually made up of three muscles, and are probably the most famous for being torn in sprinters as they accelerate out of the blocks.

I'm sure you've heard people saying that they have torn their hamstring and clutching at the back of their upper leg.

And then the gastrocnemius is a tough one to spell.

Make sure you don't forget the C in there and that this muscle is really useful for running, jumping, and pointing the toes.

For the final part of this lesson, let's make sure you can explain how muscles work in antagonistic pairs.

Muscles can only pull they cannot push.

When muscles contract, they shorten in length.

Because muscles are connected to bones via tendons, illustrated here in blue on the diagram, this shortening of the muscle results in movement at a joint.

Those muscles team up to work in antagonistic pairs across a joint.

One muscle contracts to cause the movement.

It is called the agonist or the prime mover.

The muscle that relaxes in opposition is called the antagonist.

So, we've got here the biceps working as the agonist and the triceps working as the antagonist.

They relax and lengthen in opposition to that.

Meanwhile, we've got a fixator muscle, which helps stabilise the joint.

In this example of bicep flexion, the deltoids at the top here acts as a stabiliser to hold the shoulder joint still, to mean that the agonist, the biceps, can work more effectively.

When we perform bicep curls, the biceps acts as the agonist when flexing at the elbow and lifting the weight.

Meanwhile, the triceps acts as the antagonist and is relaxing in opposition.

When we lower the weight back down again, the roles reverse.

So, the triceps will be working as the agonist during elbow extension and the biceps as an antagonist because they're relaxing in opposition to that and lengthening again.

Let's have a quick check.

So, during the upward phase of a bicep curl, which muscle is working as the antagonist? That's right, it's the triceps because the biceps are working as the agonist or prime mover during that upward phase, and the triceps are relaxing in opposition, whereas the deltoids are working as a fixator.

When we kick a ball, the quadriceps acts as the agonist when extending the knee joint.

We can see there with the straight leg, and meanwhile the hamstrings are acting as the antagonist because they're relaxing in opposition to that movement.

Again, the roles reverse when we recover the leg back down to the ground.

So, let's have another quick check with these three movement examples.

Which of the following is an example of the triceps acting as the agonist? So, causing the movement.

That's right, it's the middle one there, the net ball movement, because the triceps are extending the elbow joint, whereas in diagram A, as that person is moving from a squat and standing up, there's going to be extension at the knee joint, which will be the quadriceps acting as the agonist, and then in diagram C, that leg up in front, we've got extension at the knee joint, which will be done by the quadriceps.

We've also got flexion at the hip joint, which would be done by the abdominals, or the agonist would be the abdominals.

Time for the last task in this lesson.

I want you to explain how antagonistic pairs work.

Imagine this is a three-mark question, and then for the second part of this task, I want you to identify at least six major muscles and the movement they are creating as this sprinter accelerates out of the blocks.

Press pause while you do this.

Okay, how did you get on? In explaining how the muscles work in antagonistic pairs, you should have mentioned that the agonist or prime mover contracts to create movement.

Meanwhile, the antagonist relaxes in opposition to allow that movement to happen, and when muscles work together in this way, they are called antagonistic pairs.

And for the second part of this task, I hope you illustrated your diagram with some arrows to help you identify at least six major muscles and the movement they're creating.

You can see there the right bicep is in the flexed position or the right elbow is in the flexed position, which is created by the biceps.

Meanwhile, the left triceps has extended that elbow out behind, and then we've got the front knee in the flexed position, which means the hamstring is acting as the agonist.

Meanwhile, the quadriceps has extended that back knee and straightened it as that acceleration is happening.

You might also have labelled the gastrocnemius there, causing the pointing of the toes on that back leg.

And then we've got the gluteals that are contracting to extend the back hip.

And then at the front again, here we've got the right pectorals contracting to help add up the shoulder joint.

And meanwhile the left deltoid is abducting that left shoulder up a little bit to the side but also behind.

Let's summarise what we have learned about muscles and antagonistic pairs.

We have learned major muscles that contract to produce movements are located all over the human body.

Muscles are attached to bones by tendon, and these tendons enable the movement to happen by transferring the force into the skeletal muscle for leverage and hence movement to happen.

Muscles cannot push they can only pull.

Consequently, they work in antagonistic pairs where one the agonist or prime mover contracts to create a movement whilst the other the antagonist relaxes in opposition to enable that movement to occur.

And then, if we want to move back, the roles are reversed.

We also learned that the fixator is the muscle that helps stabilise a joint to enable more efficient movement.

The biceps and triceps are an example of an antagonistic pair operating at the elbow joint, and the quadriceps and hamstrings are also an antagonistic pair operating at the knee joint.

Thanks for joining me for this lesson.

I hope you enjoyed it, and I really look forward to seeing you again soon.

See you next time.