Equine biological systems - .Global · We tend to think of joints as being freely moveable, but some ... Equine biological systems 12 ... Revised in December 2008

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Equine biological systems

Pack 2

Joints Pack Code: EBS2

This pack you will help you to:

• identify the main types of joint and

describe how they operate.

• Describe the structure of different

types of joint.

Equine biological systems 2

About this pack

Objectives

When you have completed this pack you should able to identify the main

types of joint and describe how they operate.

The pack will help you to:

• Identify types of joint and their movements.

• Describe the structure of different types of joint.

The pack is also relevant to the National Diploma unit Principles of Animal

Science 1, and in particular to Outcome 1: Describe the structure, function

and biological systems within the animal body.

Links to other packs

This is one of a series of learning packs, each tackling an aspect of horse

biological systems. They are:

• Pack 1: The skeleton

• Pack 2: Joints

• Pack 3: Circulation

• Pack 4: Respiration

• Pack 5: The digestive system of the horse

• Pack 6: The reproductive system

• Pack 7: Oestrus and hormones

• Pack 8: Gestation and birth

• Pack 9: How animal cells work

• Pack 10: How animal cells divide

• Pack 11: Connective and epithelial tissue

• Pack 12: Muscle and nervous tissue

• Pack 13: The horse’s sensory organs


Overview of joints

Joints form the junctions between bones. Together with muscles the joints

enable the animal to move. For example, for the knee joint to bend the

hamstring muscle contracts pulling the lower part of the limb back and up.

Types of joint

We tend to think of joints as being freely moveable, but some joints only

move a little while others do not move at all.

Fibrous joints (fixed)

Fibrous joint

Bones

The bones in these joints are firmly fixed together by fibrous tissue so no

movement is possible. Examples include the sutures which unite the skull

bones and the joints between the teeth and the jawbone.

Cartilaginous joints (slightly moveable)

Bone

Cartilage

Ligament

In these joints a pad of cartilage sits between the ends of the bones. When the

cartilage is compressed slight movement is allowed. For example there are

discs between the vertebrae of the backbone. Compression of the discs

allows a slight rocking movement in the backbone.


Synovial joints (moveable)

These are freely moving joints such as the shoulder and stifle (knee) joints.

There are four types of synovial joints and each allows a different type of

movement:

• Hinge joints –the hinge joint works like a hinge with movement in one

plane, e.g. the elbow and knee joints.

• Gliding joints – in gliding joints one bone rocks against the other.

Movement is mainly in one plane, with a small amount of twisting e.g. the

wrist joint.

• Pivot joints –in pivot joints one bone pivots on another. The only

movement is rotation, and it is only found in the joint between the first

two vertebrae which allows for shaking the head.

• Ball and socket joints – ball and socket joints allow the greatest range of

movement including flexion and extension as well as rotation. The

shoulder and hip joints are examples.

Activity

Find the following types of joint in your own body, and explore the

movement(s) which each joint allows. You could also try to locate the

muscle which causes the movement.

• Cartilaginous - between the vertebrae of the spine

• Hinge – elbow/knee

• Gliding – wrist

• Pivot – between the first two vertebrae at the base of the neck

• Ball and socket - shoulder/hip


Review quiz 1

Match the following types of joints to the movement they allow:

cartilaginous free movement

fibrous slight movement

synovial no movement

hinge rotation

gliding full range of movements

pivot movement in one plane

ball and socket rocking

Synovial joints

The diagram of the knee joint below shows a synovial joint. Features of

synovial joints include:

• the joint capsule which encloses the whole joint

• synovial fluid – a sticky fluid rather like egg white which lubricates the

joint

• the synovial membrane – the inner edge of the capsule – which secretes

the synovial fluid.

The bones of the synovial joint are connected by muscles (or their tendons).

When the muscle contracts it forces one of the bones to move. In some cases

the joint is held together by ligaments to prevent it from dislocating.

The shape of the bones and the muscles involved are unique to each joint.

We consider the structure of two of the main synovial joints: hinge and ball

and socket.


Knee joint (a hinge joint)

The knee joint (stifle) is where the thigh (femur) bone and shin bone meet.

Note that it occurs high up the animal's leg compared to a human. It is a

hinge joint with a backwards and forwards movement.

The knee has the usual features of a synovial

joint

• joint capsule

• synovial fluid

• synovial membrane

• cartilage

The knee also has additional characteristics:

• the kneecap (or patella) is an irregular bone

which helps to protect the tendon which

attaches the thigh muscle (quadriceps) to the

joint

• crossed ligaments help stabilise the joint

• pads of fat (bursae) prevent friction between a

bone and ligaments/tendons, and between

the skin and the patella.

Elbow joint (a hinge joint)

The elbow joint occurs where the forearm (humerus) meets the radius and

ulna bones of the forelimb. The humerus has a rounded end which sits

against the hollow made by the radius and ulna, and the whole joint is

enclosed by the joint capsule. The complementary shapes of the two bones

plus the cartilage and the fluid allow for smooth movement. This movement

is in one plane from front to back or back to front of the animal.

When the biceps muscle contracts the joint closes like a hinge, and when the

triceps muscle contracts the joint is opens.


Hip joint (a ball and socket joint)

The following diagram shows the hip joint - a typical ball and socket joint.

Pelvis Cartilage Joint capsule

Lugament Synovial fluid Membrane Femur

The hip joint is where the rounded head or 'ball' of the thighbone (femur)

slots into the 'socket' in the pelvis. As with all synovial joints the shapes of

the bones, the cartilage and the synovial fluid help to give a smooth

movement.

In contrast to the elbow joint the hip joint can move in three planes. Each

movement is controlled by a particular muscle or combination of muscles.

For example the quadriceps or thigh muscles move the femur forwards and

backwards.

Shoulder joint (a ball and socket joint)

The shoulder joint is a similar ball and socket joint.


Review quiz 2

1 Match the following features of synovial joints with their main

purpose:

synovial fluid gives ease of movement

joint capsule stabilises the joint

cartilage secretes synovial fluid

synovial membrane lubricates the joint

ligament contains the joint

2 Sort the following joints into two lists below.

Shoulder, elbow, hip, stifle (knee)

Hinge Ball and socket


Answers to review quizzes

Review quiz 1

cartilaginous slight movement

fibrous no movement

synovial free movement

hinge movement in one plane

gliding rocking

pivot rotation

ball and socket full range of movements

Review quiz 2

1 synovial fluid lubricates the joint

joint capsule contains the joint

cartilage gives ease of movement

synovial membrane secretes synovial fluid

ligament stabilises the joint

2 Hinge Ball and socket

elbow shoulder

stifle (knee) hip

Answers to activity on page 4

This activity should have shown the wide range of different movements

which particular joints allow in humans. The movements for the equivalent

joints in animals are similar.

Further reading

William O Reece, Physiology of Domestic Animals (3rd Ed) Williams and

Wilkins, 2004

D.R. Lane and B Cooper, Veterinary Nursing (formerly Jones’s Animal

Nursing, 3rd Revised Ed). Pergamon Press, 2003


Knowledge quiz

Check your knowledge with the following questions.

1 What is the main function of joints?

2 Describe the movements allowed by;

a) fibrous joints

b) cartilaginous joints

c) synovial joints

3 Draw a typical synovial joint showing: bones, joint capsule, cartilage,

synovial membrane, synovial fluid

4 Are the following statements true or false?

a) The synovial membrane secretes synovial fluid.

! True ! False

b) Tendons are attached to muscles.

! True ! False

c) Ligaments are attached to muscles.

! True ! False

d) All synovial joints allow movement in three planes.

! True ! False

5 Name three characteristics of synovial joints which enable them to move

smoothly.


Glossary

Ball and socket joint allows movement in three planes e.g.

shoulder and hip joints

Bursae pads of fat which prevent friction in the knee

joint

Cartilaginous joint (suture) slightly moveable joint e.g. intervertebral

discs

Femur thigh bone

Fibrous joint fixed joint e.g. joints between facial bones

Gliding joint allows movement through a small range e.g.

ankle joint

Joint where bones meet

Hinge joint allows movement in one plane e.g. elbow

joint

Ligament bundle of fibres (like string) which hold

bones together in a joint

Patella kneecap

Pivot joint allows rotation only - the only one being

between the first two vertebrae which allows

nodding the head

Stifle joint knee joint

Suture (cartilaginous joint) immovable joint

Swivel joint joint between the first two cervical vertebrae

- allows rotation of the head

Synovial fluid fluid lubricating a synovial joint

Synovial joint moveable joint with fluid filling the spaces

between the articulating surfaces e.g. elbow

(hinge), shoulder (ball and socket)

Synovial membrane outer membrane of the joint capsule

Tendon fibrous tissue that connects muscle to bones


Acknowledgements This learning pack has been produced by the Land Based Colleges National Consortium Ltd.

The LBCNC is a consortium of colleges working in the land-based sector which co-operate in the development and production of quality flexible learning materials which encourage independent learning.

We would like to acknowledge the contributions made by the following individuals and colleges in the development of this learning pack.

Cover photograph: Steve Watson, Riseholme College, University of Lincoln

Developed and produced for LBCNC by Learners First

Written by May Johnstone

Illustrations: Shevanthi De-Silva

Graphic design: Eat Cake Design, Bristol

Revised in December 2008

© 2008 The Land Based Colleges National Consortium Ltd. All rights reserved.

Permission to photocopy or adapt the material in this learning pack is granted to members of the Land Based Colleges National Consortium Ltd. only.

For further information please contact the LBCNC project management team at 7 Tyne Road, Bishopston, Bristol BS7 8EE.

Tel 0117 942 3504

Documents

Equine biological systems - .Global · We tend to think of joints as being freely moveable, but some ... Equine biological systems 12 ... Revised in December 2008