Lever systems in the body

Overview

The effort, fulcrum and load of a lever, first-, second- and third-class arrangements and how to identify them, levers at the neck, elbow, ankle, knee and hip, and why third-class levers are the most common.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Name the three components of a lever.

   Model answer

   A lever has a fulcrum, an effort and a load, also called the resistance.

2. 2

   What provides each component of a lever in the human body?

   Model answer

   The joint acts as the fulcrum and the bone acts as the lever arm. The muscle supplies the effort, and the load is the body part or object being moved.

3. 3

   How is a first-class lever arranged?

   Model answer

   A first-class lever has the fulcrum between the effort and the load.

4. 4

   How is a second-class lever arranged?

   Model answer

   A second-class lever has the load between the fulcrum and the effort.

5. 5

   How is a third-class lever arranged?

   Model answer

   A third-class lever has the effort between the fulcrum and the load.

6. 6

   What is the quickest way to identify the class of a lever?

   Model answer

   The component in the middle decides the class. A fulcrum in the middle gives first class, a load gives second class and an effort gives third class.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.