lameness: its causes and treatment. 301 



greatly in shape and size, being flat, triangular, long, short, or broad, 

 ami are variously aud c-apiioiously nauuMl, some fioiu their shape, 

 some from their situation, others from their use; and thus \ve have 

 abductors and adductors — the pyramidal, orbicular, tlie digastricus, 

 the vastus, and so on. Those ^vhi(•h are under the contiol of the will, 

 known a> the voluntaiy muscles. ai)pear \n the form of fleshy struc- 

 tures, red in color, and with fibei*s of various degrees of fineness, 

 and are composed of fasciculi, or bundles of fibers, united by con- 

 nective or cellular tissue, each fasciculus being composed of suialler 

 ones but united in a similar manner to compose the larger forma- 

 tions, each of which is enveloi)ed by a structure of similar nature 

 known as the sarcolemma. Many of the muscles are imited to the 

 bones by the direct contact of their fleshy fibers, but in other 

 instances the body of the muscle is more or less gradually trans- 

 formed into a cordy or membranous structure known as the tendon 

 or sinew, and the attachment is made by the very short fibrous 

 threads through the medium of a long tendinous band, which, pass- 

 ing from a single ouc to sev(?ral others of the bones, effects its object 

 at a point far distant from its original attachment. In thus carrying 

 its action from one bone to another, or from one region of a limb to 

 another, these tendons must necessarily have smooth surfaces over 

 which to glide, either upcm the bones themselves or formed at their 

 articulations, ami this need is supplied by the secretion of the syno- 

 vial fluid, a yellowish, unctuous substance, furnished by a peculiar 

 teudinous synovial sac designed for the purpose. 



Illustrations in point of the agency of the synovial fluid in assist- 

 ing the sliding movements of the tendons may be found under their 

 various forms at the shoulder joint, at the upper part of the bone of 

 the arm, at the posterior part of the knee joint, and also at the fet- 

 locks, on their posterior part. 



As the tendons, whether singly or in company witli others, pass 

 ()ver these natural pulleys they are retained in place by strong, 

 fibrous bands or sheaths, which are by no moans exempt from danger 

 of injury, as will be readily inferred from a consideration of their 

 important special use as supports and reenforcements of the tendons 

 themselves, with which they must necessarily share the stress of 

 whatever force or strain is brought to bear upon both or either. 



We have referred to that special formation of the external surface 

 of a bone by which it is adapted to form a joint or articulation, 

 either movable or fixed, and a concise examination of the formation 

 and structure of the movable articulations will here be in place. 

 These are formed generally by the extremities of the long bones, or 

 may exist on the surfaces of the short ones. The points or regions 

 where the contact occurs are denominated the articular surface.which 

 assumes from this circumstance a considerable variety of aspect and 



