346 NAVIX ox THE HORSE. 



not in immedicate contact, or touching each other, being lined 

 by the synovial membrane, which secretes the joint-oil, thus 

 allowing perfect freedom of motion in the joint. 



The cartilage-joints, or second class of articulations, are united 

 by a tough, glistening, elastic cartilage, firmly fixed between the 

 bones it unites. The bones are also more firmly secured by 

 straps of ligament. This kind of joint admits of some degree 

 of motion, as the cartilage is very elastic. Examples of this 

 kind of articulation are found in the joints of the back-bone, or 

 spine. Some of these joints are liable to be sprained or even 

 torn apart, and the injury is very serious and difficult to 

 remedy. 



The fixed or immovable joints, or third class, are united by 

 sutures, there being no other substance between the parts 

 united. Some are held together by a tooth-like arrangement; 

 others by a projection or dowel-pin sort of fixture ; others by 

 a beveling of both plates of bone, the one overlapping the 

 other ; and others by a general roughness of the parts united. 

 These joints do not admit of any motion. Many of them are 

 not united until the animal is grown, and in later life some of 

 them become entirely obliterated and the bones united as if all 

 one bone. They are seldom the seat of injury. The bones of 

 the head and haunch-bones, or pelvis, are united by this kind 

 of suture. 



I shall now proceed to describe the particular bones of the 

 different parts of the skeleton, giving only such descriptions as 

 will be necessary to understand the nature of the various in- 

 juries to which they are liable. Bones and joints not liable 

 to disease or injury will receive but a passing notice, while 

 those which are the seats of disease or injury will be described 

 with more care. 



BONES OF THE HEAD. 



These embrace the bones of the cranium, or skull, and face. 

 The hones of the cranium are ten in number, and they form the 



