Contents
Preface
Part 1 Anatomy and Conformation
1 The whole horse
Introduction
Training the performance horse
Points of the horse
The skeleton
Skeletal muscles
2 The head and neck
Introduction
The skull
The neck
Nuchal ligament
Superficial and deep musculature
3 The forelimb
Introduction
Design and function
The skeleton
Conformation
Musculature
The lower limb
Stay apparatus of the forelimb
Care of the horse’s legs
4 The hind limb
Introduction
The hindquarters
Alignment
The skeleton
Joints of the hind limb
Muscles
Stay apparatus of the hind limb
5 The chest
Introduction
The skeleton
Musculature
Nerves
Breathing
6 The back
Introduction
Conformation
The skeleton
Joints
Ligaments
Musculature
Nerves
Back injuries and their prevention
Part 2 The Horse in Action
7 Movement and action
Biomechanics
Anatomical points affecting movement and action
Gaits
8 Walking
Footfall sequence of the walk
Walking on the right rein
Moving the forelimb forwards
Moving the hind limb forwards
Qualities of a good walk
The benefits of walking
The walk in dressage
Over tracking
Over reaching
The walk with rider
9 Trotting
Characteristics of the trot
Qualities of a good trot
Footfall sequence of the trot
The trot in dressage
The ridden trot
Lameness
10 Cantering
Characteristics of the canter
Qualities of a good canter
Changing the lead
Footfall sequence of the canter
The canter in dressage
Cantering with rider
11 Galloping
Characteristics of the gallop
Dynamic equilibrium
Changing the lead
Footfall sequence of the gallop
Role of the hind limbs
Stride length
Angulation of the hock
Warming the horse up and down
Tips for the rider about safe galloping surfaces
12 Jumping
Sequence of the jump
The ideal jumper
Evaluating jumping technique
13 Rolling and shaking
Rolling behaviour
The rolling sequence
Shaking
Index
© 2002 by Blackwell Science Ltd
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All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher.
First published 2002
Reprinted 2004
Library of Congress Cataloging-in-Publication Data
Pilliner, Sarah
The horse in motion/Sarah Pilliner,
Samantha Elmhurst, Zoe Davies
p. cm.
ISBN 0-632-05137-X Horses – paces, gaits, etc. 2. Horses – anatomy. I. Elmhurst, Samantha.
II. Davies, Zoe. III. Title.
SF289 .P56 2002 636.1’089276-dc21
2001052688
ISBN 0-632-05137-X
A catalogue record for this title is available from the British Library
Preface
We all want our horses to be able to perform to the best of their ability and we know that an effective training regime has many facets. The horse must be worked correctly, fed a balanced ration, mentally and physically healthy and well looked after. This book examines a further aspect of the horse’s performance: it is designed to help all horse owners and riders to understand how a horse moves and how its anatomy helps, or hinders, the horse’s athletic ability.
No horse has perfect conformation, but no matter what their physical characteristics all horses have the same biomechanical function. The better the horse’s conformation and physique the more efficient it will be in bio-mechanical terms. In simple terms the horse will find it easier to do the job and, as a result, will put less stress and strain on the muscles, bones, tendons, ligaments and joints so will be likely to stay sounder for longer. As the demands of competition increase, it is inevitable that success will depend upon attention to the finest detail; for example, individualised work and exercise programmes, development of the horses’ physical capacity for work, prevention and treatment of injury and speedy and effective recovery from exertion. Having more knowledge about how their horse moves and the things that it finds easy or difficult to do allows the rider to develop a work regime involving specific exercises that will enhance the horse’s performance and prolong its working life. It will also help riders recognise the limitations imposed on performance by the horse’s own physical make-up.
This book examines horse anatomy, and then considers the phases of the horse’s gaits, using sequences of photographs and detailed anatomical drawings to show the systems of support and movement at each phase. The walk, trot, canter, gallop and jump are all examined, and the effect of the rider on the horse evaluated so that the rider can take appropriate action to avoid hindering the horse. Tips are provided throughout on ways in which the horse’s life can be made easier, such as saddle fitting, warming up and cooling down procedures.
Ultimately, it is up to the rider to be sensitive to the individual requirements of his or her horse and to devise a programme of exercise and training that best suits the individual animal, taking into account its conformation, movement and action and its mental and physical ability to cope with the work.
Chapter 1
The whole horse
This book is designed to help all horse owners and riders understand how a horse moves and how its anatomy helps it to perform. It will also help riders recognise the limitations imposed on performance by the horse’s own physical make-up.
Contrary to popular belief the horse, although a natural athlete, is not a natural jumper. A loose horse, given enough excitement, will naturally perform movements that equate to passage, piaffe, courbette and capriole; however, the horse’s heavy gut and relatively inflexible spine combine to make jumping more difficult. Figure 1.1 shows the template of the whole horse used for illustrative purposes throughout this book.
Fig. 1.1 The whole horse
Observation of the following points when exercising and training the performance horse will help to protect bones, tendons, ligaments and muscles from injury:
Familiarity with the surface anatomy of the horse is important so that underlying structures can be identified. The horse has evolved over many thousands of years from a small fox-like creature with four toes on each foot to the animal it is today with a single hoof at the end of each limb. Figure 1.2 shows the points of the horse in detail.
The skeleton is the framework that supports and protects the soft tissues of the horse’s body. In Fig. 1.2 many bony areas lying below the skin are identified. Figure 1.3 shows the positions of the bones that give rise to some of the points of the horse.
Fig. 1.2 Points of the horse
Fig. 1.3 Skeleton
The horse’s skeleton is incapable of movement on its own. All movements, from a flick of the tail to the most difficult dressage manoeuvre, are brought about by a complicated system of skeletal muscles. All horses, regardless of breed, size or age, have the same arrangement of skeletal muscles, but some muscles may be better developed in certain horses depending upon their type of training. For example, the Thoroughbred dressage horse will have a more highly developed topline than a racing-fit Thoroughbred. In addition, centuries of selective breeding have led to enhanced muscular development in some breeds and types of horses. The Quarter horse, bred to sprint over a quarter of a mile, has highly muscular forelimbs and hindquarters. The sprinting Thoroughbred naturally has a more muscular physique than its steeplechasing counterpart.
The skeletal muscles are under the horse’s conscious control and enable it to adjust to the surrounding environment and to make necessary movements such as running or grazing. Muscles are attached to and hence move, various parts of the skeleton and body.
Skeletal muscles create movement by acting across joints. They are usually arranged in opposing groups which perform opposite actions to give smooth and even movements. Flexors are placed behind the bone and pull it backwards, i.e. bend the joint, whereas extensors are placed in front of the bone and pull it forwards, i.e. straighten the joint from the bent position. Usually one of the pair of muscles is much stronger than the other.
Each end of the muscle tapers from a larger muscle belly into a tendon, which attaches the muscle to the bone. Muscle bellies vary in size and shape: some are large flat sheets, such as the latissimus dorsi, and others are long and strap-like, such as the brachiocephalicus.
The horse has no muscles below the knee, and all movement in this area is carried out via tendons attached to the muscles higher up the limb. This results in the lower limbs of performance horses being prone to tendon and ligament injury. Tired muscles are more likely to result in injury.
For muscles to produce movement, they must be attached to bone at both ends. These ends are sometimes classified as the ‘origin’ and ‘insertion’, the origin being the less movable of the two ends. In most cases, when the muscle contracts (shortens) the insertion end is brought closer to the origin.
Muscles use energy to contract but do not have a way of stretching themselves again: instead the contraction of the opposing muscle is used to lengthen the shortened muscle. For example, if the splenius at the top of the neck contracts, the head is lifted and the sternocephalicus on the underside of the neck is lengthened correspondingly.
There are approximately 700 separate skeletal muscles in the horse’s body. The name of the muscle may tell us what the main action of that muscle is; for example, the digital extensor extends the toe. Others, however, are named after their places of attachment; for example, the brachiocephalicus extends from the arm (brachium) to the head (cephalicus). Names of some muscles and their actions are listed in Table 1.1.
The muscles can be considered as belonging to two systems:
The superficial muscles are shown in Fig. 1.4 and the deep musculature is shown in Fig. 1.5.
Fig. 1.4 Superficial musculature
Table 1.1 Muscle actions
Fig. 1.5 Deep musculature
Chapter 2
The head and neck
The horse’s head acts as a heavy weight that is suspended at the end of a long neck (Fig. 2.1). This arrangement allows the horse to alter its centre of gravity with ease. The position of the horse’s head and neck has a significant effect on balance and weight distribution; this is discussed in more detail in Chapter 8. When the horse’s head and neck are lowered, more weight is carried on the forelimbs and the centre of gravity moves forward. When the head and neck are raised, more weight is carried on the hind limbs and the centre of gravity moves back. Muscles originating in the forelimb and trunk that have a critical role in forelimb movement are attached to the neck bones.
The skull is made up of many flat bones fitted together like a jigsaw puzzle. These are connected together by fibrous joints known as sutures, which ossify (become bone) with age. The junctions between the bones of the skull become indistinct with age. The function of the skull is to protect very delicate organs such as the brain and eyes, and other vital sensory organs such as the nose and ears.
Fig. 2.1 The head and neck
The eyes are situated deep within the orbits, offering them some degree of protection. They each sit in a pad of fat which provides a cushioning effect. When horses are ill or starving this fat disappears and the eyes appear more sunken.
The skin which covers the horse’s face and neck is thinner than the skin anywhere else on the body.
The horse’s head evolved to be relatively large in relation to the overall size of the animal. This was due to changes in dietary habits, which developed with time from shrub browsing to a trickle-feeding herbivore. The horse needed large teeth for grinding herbage and consequently a large jawbone to accommodate them. All the lower teeth are situated in the mandible. The upper teeth are situated in sockets in the incisive (premaxillary) and maxillary bones.
Fig. 2.2 Skeleton of the head and neck
The horse’s teeth are designed to cope with a diet mainly consisting of grass, grinding away at tough stems and leaves. To compensate for the continual wear that occurs at their grinding (occlusal) surfaces, the horse’s teeth possess a very long crown, most of which is embedded in a socket. As the tooth is worn away the crown gradually emerges from the socket, compensating for the wear. The horse’s jaws need to be long to house this battery of grinding teeth; they also need to be deep to encase the long, embedded crowns. This gives rise to the characteristic shape of the horse’s head.