Muscle Levers in the Body Examples

Dan Washmuth, John Simmons
  • Author
    Dan Washmuth

    Dan has taught college Nutrition and Anatomy courses for several years. He has a B.S. in Exercise Physiology from Furman University and a M.S. in Dietetics & Nutrition from Florida International University. He is a Registered Dietitian (RD) and a Certified Exercise Physiologist (EP-C)

  • Instructor
    John Simmons

    John has taught college science courses face-to-face and online since 1994 and has a doctorate in physiology.

Learn about muscle lever systems in the body. Discover the types of levers in the body and which parts of the body act as levers. See examples of anatomical levers. Updated: 02/18/2022

Lever Systems in the Body

Lever systems in the human body are formed by muscles and bones, and the primary purpose or function of a lever system is to produce a mechanical advantage. A mechanical advantage refers to turning a small force into a larger force. A mechanical advantage can also involve turning a force into a large movement.

Skeletal Muscle Contraction

Skeletal muscles are attached to bone on each end by tendons. This attachment causes bones, and thus body parts, to move when our muscles contract. Furthermore, the nature of the attachment affects the efficiency of movement in terms of strength, speed and distance moved. Muscles work by way of lever systems which is a rigid lever, such as a bone, that moves on a fixed point called a fulcrum.

A teeter-totter is a good example of a lever system. The weight of each person on either side represent the force and load, while the pivot in the middle represents the fulcrum. If the fulcrum is in the middle of the board, two people with the same weight will balance the board.

Moving the board relative to the fulcrum will result in unbalance, making it easier for one person to push the other up. Just as moving the fulcrum of a teeter totter can increase the effectiveness of a force, the nature of muscle attachment to bone relative to the joint increases the efficiency of muscle contraction and thus, body movement. A lever moves when a force (F), or effort, is great enough to overcome a load (L), or resistance, that would otherwise resist movement. This lesson describes the three basic lever systems utilized by our muscles and bones for body support and movement.

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  • 0:06 Skeletal Muscle Contraction
  • 1:42 First-Class Levers
  • 2:16 Second-Class Levers
  • 3:36 Third-Class Levers
  • 5:26 Lesson Summary
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Which Parts of the Body Act as Levers?

Which parts of the body act as lever systems? The lever systems in the body consist of four primary parts. These four parts include:

  • Lever: Levers, also known as anatomical levers, in the human body refer to a bone.
  • Pivot/fulcrum: A pivot, also known as a fulcrum, refers to the joint that is formed by the connection between two or more bones.
  • Effort: The effort refers to the force generated by the contraction of the muscles in the lever system.
  • Load: The load, also known as resistance, refers to the weight or mass that is moved by a lever system.

For example, when a person lifts a cup of water to their mouth when drinking, their forearm is the lever, and their elbow is the pivot. The biceps brachii (muscle at the front of the upper arm) generates the force needed to lift the cup of water up to the mouth. The weight of the forearm and the weight of the glass of water is the load that is moved by this lever system.

Types of Levers in the Body

There are three primary types of levers in the body: first-class levers, second-class levers, and third-class levers. Each of these lever systems differ by the way the pivot (joint), load (weight of body), and effort (muscle contraction) are arranged. The following sections will provide information about each of these types of muscle levers in the human body.

First-Class Levers in the Body

First-class levers in the body occur when the pivot (joint) is located between the effort (muscles) and load (body weight). A first-class lever in the body is very similar to a seesaw. The pivot point of a seesaw is located between the effort (person pushing off the ground on one side) and load (weight of the person on the other end of the seesaw). Scissors are another example of a first-class lever.

An example of a first-class lever in the human body is the joint formed by the top of the vertebral column and skull, which is known as the atlanto-occipital joint. In this lever system, the skull is the lever, the atlanto-occipital joint is the pivot, the muscles at the back of the neck are the effort, and the weight of the skull is the load. The muscles at the back of the neck provide the force needed to move the head backwards, which is a movement known as neck extension.

First-class levers provide a mechanical advantage. In the example of the atlanto-occipital joint, a relatively small force generated by the neck muscles can move the comparatively heavier load of the head.


An example of a first-class lever in the body is the atlanto-occipital joint allowing a person to bend their neck backwards.

Neck extension


Second-Class Levers in the Body

Second-class levers in the body occur when the load is between the effort and pivot, and it is very similar to a wheelbarrow. In a wheelbarrow, the pivot is at the wheel, the load is in the trey, and the effort is the force is generated by the person lifting the handles upward. Second-class levers are usually the most efficient at moving heavy loads with little effort or force.

An example of a second-class lever in the body is when a person is standing on their tip toes. In this lever system, the toes are the pivot, the weight of the person is the load, and the calf muscles are the effort. The calf muscle provides the force needed to lift the body upward at the point of the toes. This movement of the toes and ankle, to stand on the tip toes, is known as plantar flexion.

Second-class levers provide a mechanical advantage. In the example of a person standing on their tip toes, the relatively small force generated by the calf muscles can raise the comparatively heavier load of the entire body. In lever systems, strength is increased as the force is moved farther away from the load.


An example of a second-class lever in the body is a person standing on their tip toes.

plantar flexion


First-Class Lever

Let's take a look at first-class levers. While the body has relatively few first-class levers, they are easy to understand as they resemble a teeter-totter. In such a lever, the load is located on the opposite side of the fulcrum as the applied force.

For example, head extension is a good example of a first-class lever system. Here, neck and back muscles apply a force to move the head. The weight of the head is the load, and the fulcrum is the joint between the skull and the vertebrae.

Plantar flexion is an example of a second-degree lever
Plantar Flexion Lever

Second-Class Lever

Let's move on to second-class levers. In a second-class lever, the load is located between the force and the fulcrum. A wheel barrow is a great example of a second-class lever system. Here, the wheel is the fulcrum, or the pivot point, the weight is the load and lifting the handles applies the force to move the load.

What about in the body? Plantar flexion, or standing on balls of our feet, is an example of a second-class lever in the body. Here, the ball of the foot is the fulcrum, the weight of the body is the load, and the contraction of the calf muscles provides a lifting force, or effort. This type of system allows a small force to move a relatively large load. In fact, moving the force further away from the load increases the strength of the lever system. However, speed and distance of movement are compromised at the expense of this increased strength. In other words, a relatively small force moves a large load a relatively short distance and moves it slowly.

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Video Transcript

Skeletal Muscle Contraction

Skeletal muscles are attached to bone on each end by tendons. This attachment causes bones, and thus body parts, to move when our muscles contract. Furthermore, the nature of the attachment affects the efficiency of movement in terms of strength, speed and distance moved. Muscles work by way of lever systems which is a rigid lever, such as a bone, that moves on a fixed point called a fulcrum.

A teeter-totter is a good example of a lever system. The weight of each person on either side represent the force and load, while the pivot in the middle represents the fulcrum. If the fulcrum is in the middle of the board, two people with the same weight will balance the board.

Moving the board relative to the fulcrum will result in unbalance, making it easier for one person to push the other up. Just as moving the fulcrum of a teeter totter can increase the effectiveness of a force, the nature of muscle attachment to bone relative to the joint increases the efficiency of muscle contraction and thus, body movement. A lever moves when a force (F), or effort, is great enough to overcome a load (L), or resistance, that would otherwise resist movement. This lesson describes the three basic lever systems utilized by our muscles and bones for body support and movement.

First-Class Lever

Let's take a look at first-class levers. While the body has relatively few first-class levers, they are easy to understand as they resemble a teeter-totter. In such a lever, the load is located on the opposite side of the fulcrum as the applied force.

For example, head extension is a good example of a first-class lever system. Here, neck and back muscles apply a force to move the head. The weight of the head is the load, and the fulcrum is the joint between the skull and the vertebrae.

Plantar flexion is an example of a second-degree lever
Plantar Flexion Lever

Second-Class Lever

Let's move on to second-class levers. In a second-class lever, the load is located between the force and the fulcrum. A wheel barrow is a great example of a second-class lever system. Here, the wheel is the fulcrum, or the pivot point, the weight is the load and lifting the handles applies the force to move the load.

What about in the body? Plantar flexion, or standing on balls of our feet, is an example of a second-class lever in the body. Here, the ball of the foot is the fulcrum, the weight of the body is the load, and the contraction of the calf muscles provides a lifting force, or effort. This type of system allows a small force to move a relatively large load. In fact, moving the force further away from the load increases the strength of the lever system. However, speed and distance of movement are compromised at the expense of this increased strength. In other words, a relatively small force moves a large load a relatively short distance and moves it slowly.

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Frequently Asked Questions

What are 1st 2nd and 3rd class levers?

First-class levers occur when the pivot is located between the effort and load. Second-class levers occur when the load is between the effort and pivot. Third-class levers occur when the effort is between the load and the pivot.

What is an example of a first class lever in the human body?

An example of a first-class lever in the human body is the joint formed by the top of the vertebral column and skull, which is known as the atlanto-occipital joint. In this lever system, the muscles at the back of the neck provide the force needed to move the head backwards, which is a movement known as neck extension.

Is a human foot a first class lever?

The human foot is an example of a second-class lever. In this lever system, the toes are the pivot, the weight of the person is the load, and the calf muscles are the effort. The calf muscle provides the force needed to lift the body upward at the toes. This movement of the toes and ankle to stand on the tip toes is known as plantar flexion.

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