The Muscles and Their Work. 27 



the lower end of the thigh bone and is attached to the 

 three bones below the fetlock, consequently the joints 

 below the hock are extended by this muscle. An 

 acquaintance with the origins, insertions and actions of 

 the limb muscles is of especial value as an aid to detect 

 and locate lameness. The apparatus for performing 

 movements in animals is as is seen composed of bones, 

 ligaments and muscles, which are brought into a more 

 or less intimate relation, we might term it frictional 

 relation. Nature has made provision to reduce the fric- 

 tion and its consequences to a minimum, by what is 

 known as joint oil (synovia). It has already been stated 

 that this fluid is present at the joints, being secreted 

 from the lining of the capsular ligament, besides these 

 locations it is also found in little bags or sacs (bursa) of 

 shapes varying with the location, placed between a ten- 

 don and bone or between two tendons. From various 

 causes, resulting in over-stimulation of the secreting 

 membrane, an overplus of this fluid is secreted, thus 

 accounting for swellings in various parts, of which bog 

 spavin and wind puffs are familiar illustrations. 



