Levers | Skeletal System 09 | Anatomy & Physiology
Summary
TLDRThis 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
🔧 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.
💪 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.
Mindmap
Keywords
💡Lever
💡Fulcrum
💡Load
💡Effort
💡Lever Arm
💡First Order Lever
💡Second Order Lever
💡Third Order Lever
💡Muscular Force
💡Joint
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
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