Unit 1: Types of Joints

Learning Objectives• All students will be able to describe what joints are

• All students will be able to classify joints into one of three categories

• All students will be able to identify the six different types of synovial joints

• Some students will be able to explain why different classifications of joints allow different ranges of movement

Joint movement – what are joints?

• A joint is a place where two or more bones meet.

• Without joints, our bodies would not be able to move.

• Joints, along with the skeleton and muscular system, are responsible for the huge range of movement that the human body can produce.

• There are several different types of joint, each producing different types and amounts of movement.

Different types of joint

There are 3 different types of joint:

1. Immovable (or fixed) joints

3. Movable (or synovial) joints

2. Slightly movable joints

1. Fixed or immovable joints

• There are fewer than 10 immovable joints in the body.

• They are sometimes called fibrous joints because the bones are held together by tough fibres.

• Where can these be found in the body?• Immovable joints can be found in the skull and pelvis, where several bones have fused together to form a rigid structure.

2. Slightly movable joints

Slightly movable joints are sometimes called cartilaginous joints.

The bones are separated by a cushion of cartilage. The joints between the vertebrae in the spine are cartilaginous joints.

The bones can move a little bit, but ligaments stop them moving too far. This is why we can bend, straighten and rotate through the back, but not too far.

bone

ligaments

cartilage

bone

3. Freely movable or synovial joints

90% of the joints in the body are synovial joints. They are freely movable.

Synovial joints contain synovial fluid which is retained inside a pocket called the synovial membrane. This lubricates or ‘oils’ the joint.

All the moving parts are held together by ligaments.

These are highly mobile joints, like the shoulder and knee.

Synovial fluid

Synovial membrane

Different types of joint

Freely movable (synovial) jointsThe joint capsule is an outer sleeve that protects and holds the knee together.

The synovial membrane lines the capsule and secretes synovial fluid – a liquid which lubricates the joint, allowing it to move freely.

Femur

Tibia

Joint capsule

Synovial membrane

Synovial fluid

Ligaments hold the bones together and keep them in place.

Cartilage

Smooth coverings of cartilage at the ends of the bones stops them rubbing together and provide some shock absorption.

Synovial Joints

There are six different types of synovial joints:Please use this website very informative http://oldlearnzone.loucoll.ac.uk/NLN/Science/Biology/Life%20Sciences/workshop3_RH4_Joint%20structure%20and%20function/69EC3221-AE3F-41A9-AED0-4092E5834A91/485_sco.html

• Hinge Joint• Ball and socket joint• Ellipsoid (condyloid joint)• Gliding Joint• Pivot Joint• Saddle joint

Activity 1

Working in pairs.

Provide a description of the six different joint of the skeleton, providing examples.

Ball and Socket Joints

In ball and socket joints, the rounded end of one bone fits inside a cup-shaped ending on another bone.

Ball and socket joints allow movement in all directions and also rotation. The most mobile joints in the body are ball and socket joints.Examples: Shoulders and hips.

Hip

Pivot Joints

Pivot joints have a ring of bone that fits over a bone protrusion, around which it can rotate.These joints only allow rotation.

Examples: The joint between the atlas and axis in the neck which allows you to shake your head.

Axis

Atlas

Saddle Joints

In saddle joints, the ends of the two bones fit together in a special way, allowing movement forwards and backwards and left to right, but not rotation.

Examples: The thumb is the only one.

Ellipsoid (Condyloid) Joints

Condyloid joints have an oval-shaped bone end which fits into a correspondingly shaped bone end.

They allow forwards, backwards, left and right movement, but not rotation.

Examples: between the metacarpals and phalanges in the hand.

Gliding Joints

Gliding joints have two flat faces of bone that slide over one another.They allow a tiny bit of movement in all directions.

Examples: between the tarsals in the ankle.

Hinge Joints

Hinge joints – as their name suggests – only allow forwards and backwards movement.

Examples: The knee and elbow.

Elbow

Types of synovial joints

Activity 2In the same pairs you were in earlier: You need to provide a sporting

example for the use of each joint.

For example: During the butterfly stroke, the ball and socket joint of the shoulder allows the swimmer’s arm to rotate.

What would happen to the performance if there was another type of synovial joint present?

(You might have to present back to the rest of the class)

Class Discussion

Why do some joints allow for different ranges of movement?

Joint movement – how do we move?

Movements

What other movements are we missing?

Working with a partner:

Take it in turns to demonstrate a simple sporting movement, for example performing a biceps curl or taking a step forward.Together, analyze the movement and decide what types of movement are occurring at each joint.

Now take it in turns to name a joint. Ask your partner to demonstrate and name all of the movements possible at that joint. For example, the hinge joint at the elbow shows flexion, extension and slight rotation.