26 FISTULA AND POLL-EVIL 



esses below. The posterior part is attached to 

 the second and third dorsal spines and extends 

 in the form of several digitations forward and 

 downward where its brush-like fibers reach the 

 spines of the fifth and sixth cervical segments. 

 The fibers of the ligament are more spare than 

 in the anterior part and sometimes do not even 

 reach the sixth vertebra. Between the anterior 

 and the posterior parts is a space of consider- 

 able dimensions which especialh^ in horses of 

 good flesh contains a mass of fatty tissue. This 

 opening is at the level of the extremity of the 

 second dorsal spinous process and is the seat 

 of typical fistula of the withers. It is the space 

 where the sacculation of fistula begins. 



The supraspinous ligament is a structure 

 composed of white fibrous tissue and extends 

 along the dorsal region to the sacrum. It is 

 the continuation of the ligamentum nucha? 

 posteriorly. A careful dissection of this struc- 

 ture fails to show^ that it begins as an independ- 

 ent structure, as its fibers although they change 

 in structure from yellow elastic to white fibrous 

 tissue, are simply continuations of each other. 

 From the surgical standpoint the supraspinous 

 Hgament and the ligamentum nuchge must be 

 regarded as a single apparatus which changes 

 in the character of its tissue at the crest of the 

 withers. Over the crest it is a verv thick, dense 



