Joints – SS2 Biology Lesson Note (First Term)

A joint is the place where the ends of two bones meet. Joints hold the bones together and allow the skeleton to move. Most joints contain fluid that helps them move in the direction needed. Joints give the body form, support, stability and movement.

Behavioural objectives

By the end of the lesson, students should be able to:

• define a joint;
• name the six types of freely movable joints;
• give one example of each type of joint;
• state the functions of the human joints.

What are the types of joints?

There are several types of joints in the body. This note covers the most common ones.

There are six types of freely movable joints:

1. Ball and socket joint. This joint allows movement in all directions. It is a rounded head of one bone sitting in the cup of another bone. Examples include your shoulder joint and your hip joint.

2. Hinge joint. The hinge joint is like a door. It opens and closes in one direction. Examples include your elbow joint and your knee joint.
3. Condyloid joint. The condyloid joint allows movement, but no rotation. Examples include your finger joints and your jaw.
4. Pivot joint. The pivot joint can also be called the rotary joint. Examples are the joints between the ulna and radius bones in your forearm, and the joint between the first and second bones in your neck.

5. Gliding joint. The gliding joint can also be called the plane joint. This joint can only move in one direction, up and down. An example is the joint in your wrist.
6. Saddle joint. The saddle joint does not allow round movement, but it does move back and forth and side to side. An example is the joint at the base of your thumb.

What are the functions of the human joints?

The human joints provide the following for the body:

1. Form
2. Support
3. Stability
4. Movement

Evaluation

1. What is a joint?
2. Name the six types of freely movable joints.
3. Which type of joint allows movement in all directions? Give two examples.
4. State the functions of the human joints.

Assignment

Write short notes on the hinge joint and the pivot joint. Give two examples of each.