136 THE SURGICAL ANATOMY OF THE HORSE 



band appears always to be in a degree of tension which causes a move- 

 ment of the stifle to bring about a simultaneous movement of the hock 

 and vice versa. 



Rupture of this muscle or its tendons gives rise to most alarming 

 symptoms, to which attention has been frequently drawn during the 

 past century. By some early observers the symptoms were attributed 

 to some nervous affection. Others, again, thought that the hock was 

 dislocated. Still others attributed them to fracture of the tibia ; whilst 

 there were those whose attention was particularly attracted to the 

 peculiar effect produced on the gastrocnemius, and were led to the 

 conclusion that the condition was some affection of this muscle. 



Dick appears to have considered the gastrocnemius as being paralysed. 

 According to MoUer, the first to give a complete account of this condition 

 was Hertwig. 



The superficial division of the muscle is the more frequently ruptured, 

 owing to the slight degree of elasticity which it possesses and also to the 

 condition of tensity to which it is continually subjected. Rupture is 

 most commonly found towards the middle third of the muscle. Occa- 

 sionally the muscular or deep division is also partially ruptured. 

 Frequently neither the muscle nor one of its tendons is completely 

 ruptured, and the symptoms result from a severe sprain, with laceration 

 of some of the fibres. Occasionally the common tendon of origin of the 

 extensor pedis and the superficial division of the fiexor metatarsi is so 

 affected. This, as we have already remarked, is an extremely thick and 

 powerful tendon. Complete rupture of it is on this account very rare. 

 When it is sprained in the manner indicated we have inability, not only 

 of the flexor metatarsi, but also of the extensor pedis. It sometimes 

 happens that the flexor metatarsi is neither ruptured nor sprained, but 

 that one or more of its tendons of insertion have become detached from 

 the bones into which they are inserted. 



The symptoms presented depend to a great extent upon the seat ot 

 the injury. Certain symptoms are, however, somewhat constant. We 



