Levers | Skeletal System 09 | Anatomy & Physiology

Summary

This video introduces the concept of levers, focusing on the anatomy and physiology of lever systems in the human body. It explains key components of levers: fulcrum, load, effort, and lever arm. The video details the three types of levers—first, second, and third order—highlighting how each operates and providing real-life examples like neck movements, calf raises, and bicep curls. The presenter uses a simple mnemonic (FLE: Fulcrum, Load, Effort) to help viewers remember the order of the levers. The video encourages questions and engagement from viewers.

Takeaways

• 🔺 The fulcrum is the pivot point of a lever, often represented by a joint or contact point with the ground.
• 📦 The load, also called resistance, is the object or mass that the lever system is trying to move, such as a dumbbell or the body's weight.
• 💪 The effort refers to the force applied to the lever system, typically the muscular force in anatomy and physiology.
• 🦴 The lever arm is the bone on which the muscle exerts its force, acting as the lever in the system.
• 1️⃣ A first-order lever has the fulcrum between the load and the effort, like the neck lifting the head.
• 2️⃣ In a second-order lever, the load is between the fulcrum and the effort, such as in a calf raise where body weight is centered over the ankle.
• 3️⃣ A third-order lever places the effort between the fulcrum and the load, like a bicep curl where the muscle insertion is central to the movement.
• 🧠 First, second, and third-order levers can be remembered using 'FLE': fulcrum is central in first, load in second, and effort in third.
• 🧍 Most levers in the human body are third-order, where the effort is centrally located between the fulcrum and the load.
• 💡 Common examples in the body: first-order (neck), second-order (calf raise), and third-order (bicep curl).

Q & A

What is the fulcrum in a lever system, according to the script?

The fulcrum is the point at which the lever arm pivots. In anatomy, this is usually a joint or a contact point, such as where the feet or hands meet the ground.

How is the load defined in the context of a lever system?

The load, sometimes known as resistance, is the mass or object that the lever system is set up to move. In human anatomy, this can include items like a dumbbell, a football, or even the body’s own weight.

What does the red arrow represent in the script’s explanation of levers?

The red arrow represents the effort, which is the force applied to the lever system. In anatomy, effort refers to the muscular force that contracts to pull on a bone.

What is a lever arm in anatomical terms?

In anatomy, the lever arm is the bone or bones upon which the contracting muscles exert their force or effort.

How is a first-order lever defined in the script?

A first-order lever has the fulcrum positioned between the load and the effort. The fulcrum doesn't have to be in the exact center but must be between the other two components.

What is the difference between a second-order lever and a first-order lever?

In a second-order lever, the load is placed in the center, with the fulcrum at one end and the effort at the other. In contrast, a first-order lever has the fulcrum in the center.

What arrangement defines a third-order lever?

A third-order lever has the effort placed in the center, with the fulcrum and load at opposite ends. The effort is applied between the fulcrum and the load.

What is the memory tool suggested in the script to remember the types of levers?

The memory tool is '1-2-3 FLE,' which stands for fulcrum in the center for the first order, load in the center for the second order, and effort in the center for the third order.

Can you give an example of a first-order lever in the human body?

A good example of a first-order lever is in the neck, where the atlas vertebra acts as the fulcrum, the head’s weight is the load, and the posterior muscles of the neck provide the effort to lift the head.

What is an example of a second-order lever in human movement?

Standing on your tiptoes is an example of a second-order lever. The fulcrum is the contact point with the ground, the load is the body's weight, and the effort is provided by the calf muscles via the Achilles tendon.

What is the most common type of lever in the human body, and can you provide an example?

The most common type of lever in the human body is a third-order lever. An example is the bicep curl, where the elbow joint is the fulcrum, the dumbbell is the load, and the bicep's insertion point provides the effort.

Outlines

00:00

🔧 Introduction to Levers and Key Concepts

The video begins by introducing the topic of levers, a potentially tricky subject. It explains the basic components of a lever system using symbols. The red triangle represents the fulcrum, the pivot point of the lever arm, typically a joint or a contact point like where the feet or hands meet the ground. A red square represents the load, also known as resistance, which is the object or mass that the lever is set to move (e.g., dumbbell, body weight). The red arrow signifies the effort, the force applied to the system, often the muscular force in anatomical terms. Finally, the lever arm refers to the bones on which the muscles exert force. The video explains three types of lever systems based on the arrangement of fulcrum, load, and effort: first-order (fulcrum in the center), second-order (load in the center), and third-order (effort in the center). A mnemonic '1-2-3, FLE' helps remember the sequence: fulcrum in the center for first order, load for second, and effort for third.

05:00

💪 Examples of Levers in the Human Body

The video illustrates examples of each lever type within the human body. A first-order lever is exemplified by the neck when lifting the head. Here, the fulcrum is the atlas vertebra, the load is the head's weight, and the effort comes from the neck muscles pulling downwards. A second-order lever is shown through a calf raise. The fulcrum is where the toes contact the ground, the load is the body's weight over the ankle, and the effort is from the calf muscles via the Achilles tendon. Third-order levers, the most common in the body, are demonstrated with a bicep curl. The fulcrum is the elbow joint, the load is the dumbbell and forearm, and the effort is from the bicep muscle insertion point, which is between the fulcrum and load. The video emphasizes understanding these arrangements and their prevalence in the body.

Keywords

💡Lever

A lever is a simple machine consisting of a rigid bar that pivots around a point (fulcrum) to move a load with an applied force (effort). In the context of anatomy and physiology, bones act as levers, and muscles apply the force needed to move them. The video explains different types of levers and their arrangement in the body.

💡Fulcrum

The fulcrum is the pivot point of a lever. It is the point around which the lever arm rotates. In the human body, the fulcrum usually refers to joints, but it can also refer to contact points with surfaces, such as where feet or hands meet the ground. For example, in a bicep curl, the elbow acts as the fulcrum.

💡Load

The load, also known as resistance, is the object or mass that the lever is set to move. In anatomy, this could be a dumbbell, a body part, or even the weight of the body itself. In the example of a calf raise, the load is the weight of the body placed over the ankle.

💡Effort

Effort refers to the force applied to a lever system. In the context of human anatomy, the effort is the muscular force applied to move a bone or a load. For instance, when performing a bicep curl, the effort comes from the contraction of the bicep muscle.

💡Lever Arm

The lever arm is the rigid bar or structure that transmits the applied force (effort) to move the load. In the human body, bones function as lever arms, allowing muscles to apply force and generate movement. For example, the bone in the lower arm acts as the lever arm in a bicep curl.

💡First Order Lever

In a first order lever, the fulcrum is placed between the load and the effort. An example provided in the video is the neck, where the fulcrum is the atlas vertebra at the top of the spine, the load is the weight of the head, and the effort comes from the neck muscles lifting the head.

💡Second Order Lever

A second order lever has the load placed between the fulcrum and the effort. The video uses a calf raise as an example, where the fulcrum is the point of contact with the ground, the load is the body weight, and the effort is applied by the calf muscles.

💡Third Order Lever

In a third order lever, the effort is applied between the fulcrum and the load. Most levers in the human body are third order levers. For example, in a bicep curl, the elbow acts as the fulcrum, the load is the dumbbell, and the effort is applied by the bicep muscle.

💡Muscular Force

Muscular force is the effort applied by muscles to move bones and create movement in a lever system. It plays a critical role in all types of lever systems in the body. For instance, during a bicep curl, the contraction of the bicep muscle generates the muscular force needed to lift the dumbbell.

💡Joint

A joint is the point where two bones meet and allow for movement. In the video, joints are often referred to as fulcrums in the body’s lever systems, such as the elbow in a bicep curl or the neck joint when lifting the head.

Highlights

Introduction to levers and key terms used in the lever system such as fulcrum, load, effort, and lever arm.

The fulcrum is the point where the lever arm pivots, typically a joint or contact point with a surface.

Load, also known as resistance, represents the mass or object that the lever system is set up to move, like a dumbbell or body weight.

Effort is the force applied to the system, usually muscular force in anatomy, where muscles contract to pull on the bone.

Lever arm refers to the bone or bones on which the muscles exert force in anatomy and physiology.

First-order levers have the fulcrum in the center between the load and the effort, and an example is the neck joint used to lift the head.

Second-order levers have the load in the center, with examples like a calf raise or standing on tiptoes.

Third-order levers have the effort in the center, with the bicep curl being a common example.

The memory tool '1, 2, 3 FLE' helps to remember the lever orders, where 1 stands for fulcrum, 2 for load, and 3 for effort.

In the first-order lever of the neck, the atlas vertebra acts as the fulcrum, the weight of the head as the load, and the posterior neck muscles provide the effort.

In the second-order lever example of a calf raise, the fulcrum is the contact point with the ground, the load is the body weight, and the effort comes from the calf muscles.

In the third-order lever example of a bicep curl, the elbow joint is the fulcrum, the load is the dumbbell, and the effort comes from the bicep's insertion point.

The majority of the body’s lever systems are third-order levers, where the effort is applied between the fulcrum and the load.

Students often get confused with third-order levers because they associate the bicep contraction with the other side of the joint, but the effort is applied between the fulcrum and load.

The video ends with an invitation to ask questions, like, and subscribe for more educational content on anatomy and physiology.

Transcripts

well guys welcome to this video on

levers now this can sometimes be a bit

of a tricky subject

so let's take our time and uh see if we

can explain this as clearly as we can

so let's just define our key terms these

are the symbols that i'm going to be

using in this video and they represent

these key terms or key parts of the

lever system so first off

we have this red triangle which

represents the fulcrum now the fulcrum

is the point at which the lever arm

pivots

and in our case um as far as amp is

concerned the fulcrum usually just means

the joint

but it might also mean a contact point

for example contact point with the

ground

where the feet meet the ground or

whether hands meet the ground or

something like that or some other

some other surface so the fulcrum is the

pivot

it's a joint usually or some contact

point

second key uh key term

is this we're going to use a a red

square to represent our second key term

and that is the the idea of the load and

again load is sometimes just as fulcrum

is sometimes known as pivot the load is

also sometimes

known as resistance and this is um this

is the mass or the object that the lever

system is set up to move so it might be

a dumbbell it might be a football it

might be a cricket bat or it might

simply just be the weight of the body

next we've got this red arrow the red

arrow represents

the effort

and the effort is the force that's being

applied to the system to the lever

system in the case again of anatomy and

physiology it means the muscular force

so where the muscle is

contracting in order to pull on the bone

which brings us to the last

piece in the puzzle

and that is the lever arm the lever arm

so again from an anatomy and physiology

perspective the lever arm essentially

just means the bone or the bones on

which the contracting muscles are

exerting

their muscular force or their effort so

we fulcrum

load

effort

and lever arm and there are basically

three ways we could arrange these

um

these elements in a lever system and

each one has its own

name so let's look at those

so here's our lever arm

and we're going to place a fulcrum

somewhere roughly centrally to the lever

arm and then either side of the fulcrum

we're going to have our load and

effort

so whenever we have the fulcrum in the

center between the load and the effort

um we have a particular type of lever

system and that is known as a first

order lever so where the fulcrum is in

the center and it doesn't have to be in

the middle of the lever arm it just has

to be in the center of the other two

components so it has to be in between

the load and the effect if it's between

the load and the effort it's a first

order lever and the four can you know it

might be slightly closer to the effort

it might be slightly closer to the load

but whatever it doesn't really matter if

the fulcrum is in the center between

those other two elements then we've got

ourselves a first order lever so how

else could we arrange these things so

here's our lever arm again this time

instead of having the fulcrum in the

center

we're going to have the fulcrum at the

end so the fulcrum is at one end and

then this time in the center instead of

the fulcrum we've got the load so we've

put the load in the middle and we've got

the effort at the end

now this

arrangement is known as a second order

lever so whereas a first order lever has

the fulcrum in the center the second

order lever has the load

in the center

let's do another example then there's

only one other way we could arrange

these things

uh let's have our fulcrum at an end

and the load at the other end and this

time we've got the effort

in the center now with the effort in the

center you can probably guess where

we're going with this

to have the effort in the center means

we've got a third order lever

so the effort is there in the center so

if the fulcrum is in the center it's

first order

if the load is in the center it's second

order and if the effort is in the center

then it's third order sometimes the

orders are known as classes as well so

you might you might read or see

elsewhere first class second class third

class it's exactly the same thing it's

just different terminology

how do i remember this

there's a really handy little

memory tool for this very simply first

second third order levers one two and

three and then we've got the fulcrum the

load and the effort in the center so we

can say

one two three f for fulcrum

l for load e for effort one two three f

l e and that reminds us what comes in

the center of each of the orders of

lever so one two three fle first order

fulcrum second order load

third order effort

let's do some examples in the human body

then where do we find these different

orders of lever so a good example for a

first order lever where we have the

fulcrum in the center

is in the neck so if you wanted to to

lift up your head lift up your eyes to

look to the skies

you would use the first order lever that

you have in your neck so the fulcrum is

going to be in the center and in this

case the fulcrum is the atlas vertebra

at the top of the vertebral column

which inserts or articulates with the

base of the cranium so on either side of

the fulcrum now we have the load and the

effort now in this case the load is

simply the weight of the head

and on the other side of the fulcrum

we have the effort and the effort is

produced by the contraction of the

posterior muscles of the neck

pulling downwards in this example to

lift up the load uh to enable you to

lift up your head so because the fulcrum

is in the center we've got ourselves a

first order lever

second order levers then a good example

here is a calf raise or to stand on your

tiptoes

um and in this example

um as we've got on the diagram already

uh we've got a fulcrum and the fulcrum

in this example is not it's not so much

a joint it's more the contact point with

the ground

um but we've got of course the load in

the center and here the load is the

entire body weight which is placed

directly over the sort of the center of

the ankle

and then behind the body weight to the

other side of the load meaning that the

load is in the center we have the effort

which of course is the insertion of the

calf muscles by the achilles tendon into

the back of the heel so the effort is

behind the load the load is in the

center and the fulcrum is on the other

side therefore a really good example of

a second order lever

now the third order levers there's loads

of these in the body and the majority of

the body's levers are in fact third

order levers so let's just do one

example and we'll use a bicep curl as an

example

so here we have uh initially the fulcrum

the fulcrum is the joint and in this

case the elbow joint

the load is the dumbbell itself of

course plus the the weight of the the

lower arm

but obviously mostly the dumbbell here

and then the effort is actually central

and which is why it's a third order

lever now sometimes some students get a

little confused about this because um

isn't it the case is the bicep that does

the bicep curl and isn't the bicep on

the other side of the joint yes that's

true but the what we're after is where

the insertion of the muscle is so where

does the actual effort occur the effort

when the bicep contracts although the

bicep is the other side of the joint

it obviously crosses the joint by a

tendon and the tendon attaches in

between the joint and the dumbbell the

tendon attaches in between the fulcrum

and the load therefore the effort

produced by the muscle is actually

acting on the lever

centrally in between the fulcrum and the

load and that is why it's a third order

lever and you'll see that repeated again

and again

throughout the body

so i hope that's been helpful to you any

questions or queries please put them in

the comments and i'll get back to you

other than that please don't forget to

like the video

subscribe it really helps me out so i'd

appreciate that very much but other than

that enjoy the rest of your day take

care see you in the next video

you