A journey through the horse's body - Dr. Christina Fritz - ebook
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This book means a fascinating journey through the horse's body! How does a horse work? What does it need to move, breathe and eat? What structures does it have and how does it use them? Which structures can we see and feel? Which functions can we observe? This book quickly enables the reader to draw conclusions about functional disorders and their treatment. The descriptions are easy to understand and the memorable pictures explain even the most complicated associations.

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Dr. Christina Fritz

 

A Journey through the Horse’s Body

 

I would like to thank Lars and Lennard Wittenburg for their patience and support in the creation of this manuscript during the family holiday.

 

 

 

Imprint:

Copyright ©2012 Cadmos Publishing Limited, Richmond, UK

Copyright of original edition © 2011 Cadmos Verlag GmbH, Schwarzenbek, Germany

Design: Ravenstein, Verden

Setting: Das Agenturhaus, Munich

Translation: Helen McKinnon

Editorial of the original: Maren Müller

Editorial of this edition: Christopher Long

 

Cover image: Edition Boiselle/Susanne Retsch-Amschler

Photographs in book: Cadmos archive, Dr. Christina Fritz, Kai Kreling,

Dr. Richard Maurer, Christiane Slawik

Illustrations in book: Juliane Denmann, Maria Mähler, Susanne Retsch-Amschler

 

Printed by: Grafisches Centrum Cuno, Calbe

E-Book conversion: Satzweiss.com Print Web Software GmbH

 

All rights reserved: No part of this book may be reprinted or reproduced or utilized in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publisher.

 

British Library Cataloguing in Publication Data

A catalogue record of this book is available from the British Library

 

Printed in Germany

 

ISBN 978-0-85788-006-2

eISBN 978-0-85788-724-5 (EPUB)

eISBN 978-0-85788-725-2 (MOBI)

 

www.cadmos.co.uk

Foreword

Dear Reader,

 

Welcome to a voyage of discovery through the horse’s body. In this book, I will describe to you the structure and function of all of the parts of the horse’s body. The book features extensive image material to help clarify the theoretical explanations. By understanding anatomy, you will be able to ride your horse better and keep him in an environment that suits him best.

Look at your horse in a whole new light. See him not just as your friend and partner, but as the steppe animal, the herd animal, the flight animal that has evolved over millennia to become better and better adapted to his environment. Above all, the horse is an animal of movement that, in the wild, would be active for up to 16 hours a day in search of food. This is only possible with a specially adapted musculoskeletal system, to which a particularly detailed chapter of this book has been dedicated. The cardiovascular system and the respiratory system are also adapted to this life in motion. The horse’s digestive system is perfectly suited to the diet of a steppe animal and is fundamentally different from that of the carnivorous dog or omnivorous human. I will also go into these special features in greater depth in this book.

 

Embark on a journey through the horse’s body and you will never look at your horse in the same way again!

 

Basic Anatomical Principles

 

People have been interested in anatomy since the dawn of time. The term “anatomy” is derived from the Latin anatemnein, which means “dissect” or “dismember”. Correspondingly, we owe most of our anatomical knowledge to the people who dissect the dead and make the functional units visible. By breaking down the body into its smallest units, we can understand its functions and connections and therefore the body as a whole. This means that anatomy is not only the basis for veterinary treatment, i.e. understanding which body part no longer works so that it can be fixed, but also the basis for correct riding.

 

 

The points of the horse. (Illustration: Retsch-Amschler)

 

Riding and Veterinary Latin

You will come across many Latin terms in this book, because Latin has always been the language of medicine. But don’t worry; it is not as difficult as it sounds! Some of these Latin names have already found their way into our language. For example, many riders will be familiar with the longissimus, the long back muscle that transfers the power of the hindquarters to the forehand, like an elastic band. Many of these terms are very flowery, such as os sacrale, the sacrum, whose name is derived from its cross shape. Others have arisen from comparative anatomy between the species. A musculus extensor (literally translated: extensor muscle) may also have a bending function, depending on how the joints are positioned in relation to one another in the animal concerned. Not all animals are unguligrades like horses, which walk on the tips of their toes like ballerinas. Many are digitigrades, such as cats or dogs, for example and some animals are plantigrades, such as human beings or badgers. Nevertheless, the same muscle always has the same name in all animals.

The Latin terms in this book will also enable you to understand your vet or equine osteopath better when they are discussing your horse’s health problems with you. We will also use non-Latin words in this book that have made their way into our language, such as knee joint or fetlock. Terms have been adopted into the language of riding that are not anatomically correct, such as “knee” for the carpal joint, which can lead to misunderstandings.

Terms that come both from the language of riding and the language of medicine are used to describe anatomy. In anatomy, the obvious English terms such as “above” or “below” are not used to describe directions, because these terms can change, for example, if the horse has to be turned onto its back for an operation. That is why we use Latin terms such as dorsal or ventral. In equitation we also use words to describe direction of movement. Adduction describes pulling the leg towards the midline and abduction describes the lateral stretching of the leg away from the midline. The adduction/abduction movement is particularly important for the half-pass.

 

The adduction/abduction movement can easily be recognised in the half-pass. (Photo: Slawik)

 

 

Flexion, i.e. upwards curving, of the back is the aim of all riding. In order for the back to flex, the sacrum, i.e. the end of the spinal column, and the pelvis, must tilt into a “sitting” position. This movement is also described as flexion. The opposite movement, i.e when the back is pushed down, is called extension, as is the movement of the pelvis and sacrum when stretching out the hindquarters. 

 

We can clearly see how horses arch their backs when they buck. (Photo: Slawik)

 

This horse’s back is clearly extended. (Photo: Slawik)

 

An Overview of Anatomical Terms

Regions:  

Forehand: All of the parts of the horse from the nose to the shoulder, including both front legs.

Midsection: The area between the forehand and the hindquarters, i.e. the back, chest and abdominal cavity with their respective organs.

Hindquarters: Everything behind the flank, i.e. croup and back legs.

Parts of the body:

Equine body parts have names very similar to human body parts: head, neck, shoulder, upper arm, forearm, back, abdomen, chest, hip and thigh. The only difference is that horses walk on four legs, i.e. on their hands and feet or, more precisely, on the tips of their toes. Everything below the knee joint or hock is called the “distal limb”.

Terms of location:

Cranial: Forwards or in the direction of the head. With regard to the head, we also say rostral for the direction of the nose or caudal for the direction of the ears.

Caudal: Backwards or towards the tail.

Dorsal: Upwards or towards the back.

Ventral: Downwards or towards the abdomen.

Medial: Towards the midline of the body. In the leg, this means the adduction movement.

Lateral: Sideways away from the midline of the body. In the leg, this means the abduction movement. 

 

Anatomical Terms of Location. (Photo: Slawik)

 

The following terms also apply to the leg:

Proximal: In the direction of the body.

Distal: In the direction of the foot.

Palmar: The back of the foreleg, i.e. the “palm” side.

Plantar: The back of the hind leg, i.e. the “sole” side. The fronts of the legs, i.e. the back of the hand or the back of the foot, are described as “dorsal”. 

The Musculoskeletal System

Horses are built for movement. (Photo: Slawik)

 

The musculoskeletal system of a horse consists of a passive part, by which we understand the bones and joints and an active part that encompasses all of the muscles. Both parts need to interact in order for the horse to move. Muscles can still contract without bones but it will get them nowhere and a skeleton without muscles could not even stand, because even that requires muscular tension. The skeleton also provides the required stability and the points of influence for the muscles that then move the body.

 

The Bones

The role of the bones in the musculoskeletal system is to act as a support and point of influence for the muscles, tendons and ligaments and to support the weight of the body.

Bone is not dead tissue, as you might think from anatomical specimens. Only the mineral calcium component of the bone is left after preparation as a specimen, in the same way that a coral on land is just the dead calcium skeleton of the living organism. The mineral component of bones gives them their strength, which makes bone the hardest substance in the body, after tooth enamel. However, the mineral component, mainly calcium, phosphorous and magnesium, only makes up around half of bone. In an adult horse, the skeleton contains around 9 to 10 kilograms of calcium, around 20 percent of which can be mobilised if required. The bones are therefore one of the body’s most important mineral stores. A quarter of the weight of bone is water and another quarter is living bone cells. These bone cells (osteocytes) ensure that a bone can always be grown, broken down or reconstructed and therefore adapted to the strain it is under. The activity of these bone cells is particularly impressive after a bone has been broken, when the gap between the two fragments is closed by new bone material within a few weeks. However, osteocytes are also responsible for the formation of exostoses because they build up extra material to stabilise the bone if the periosteum becomes inflamed or if the slightest crack appears in the bone.

 

Exostosis on the splint bone, palmar view. (Photo: Fritz)

 

Did you know …?

A great deal of weight rests on the cannon bones, which increases further when the horse is ridden. The cannon bones of an unridden horse have a round cross section, which becomes a transverse oval when the horse is ridden. In this instance, the body produces more bone mass to be able to bear more weight.

 

 

Cross section of a horse’s leg. (Photo: Fritz)

The Structure of Different Bones

In terms of structure, we can differentiate between short bones, flat bones and long bones. Short and flat bones are only made from spongy bone material (spongiosa) and the thin, hard cortical substance (corticalis) that covers them. Flat bones include the cranialor pelvic bones, but the ribs are also considered to be flat bones because of their structure. Short bones include, for example, the short pastern bone at the coronet band. All long bones are tubular bones, for example the large, long bones of the limbs. Long bones have a medullary cavity at their centre, which is surrounded by a thick, particularly stable layer of bone (cortical or compact bone). The ends of long bones are made of spongiosa. 

Bones have a trabecular structure to achieve the required strength at a simultaneously low weight. That means that they are not only made of a compact mass of calcium as we would initially think from their appearance, but from finely branching trabeculae that are particularly visible in the area of the spongiosa. These trabeculae are aligned along the tensile and compressive forces that act on the bones. This enables the bone to be solid and flexible at the same time.

 

The periosteum is on the outside of all bones. It is made of firm connective tissue (fibrosa). There is a layer on the inside where the bone cells are, called the osteoblastic zone. Exostoses may be formed here if the periosteumis damaged, by a blow for example. A great many bundles of collagen fibres, known as Sharpey’s fibres, extend from the periosteum into the bones and attach them firmly to the periosteum. Blood vessels also penetrate into the bone from the periosteum and supply the osteocytes that lie deep inside the bone, as well as the cells in the bone marrow. At the epiphysis or end part of the bone, the bundles of collagen fibres continue into the upper layer of the articular cartilage and radiate into the fibrous joint capsule. There they ensure a close connection between the articular cartilage and the bone, as well as between the joint capsule and the bone. The tendons and points of influence of the muscles also originate from the periosteum and their fibres go into the bones. Bones and tendons therefore grow firmly together. 

The medullary cavity is found inside the long bones and is filled with bone marrow that is well supplied with blood (red bone marrow). Among other matter, the red bone marrow is made up of stem cells for red and white blood cells. Flat bones also contain red bone marrow. While the bone marrow in the long bones reduces in size and only consists of fat (white bone marrow) in older animals, the red bone marrow in flat bones is there for life and forms the blood cells that are essential for existence.