feRACHlAL Paralysis 



507 



rib and the scapula. If the first rib is fractured the con- 

 tractions of the scalenus muscle displace the segments an- 

 teriorly and draw upon the nerves which pass around its 

 anterior border, and thus paralyze them. This accident con- 

 stitutes the most serious form of the disease — the incurable 

 form,— as the displaced rib permanently prevents the nerve 

 from functionating. When the disease is due simply to a 

 bruising of the plexus or a stretching of the nerves the ner- 

 vous lesion may be capable of undergoing a successful re- 

 generation, and recovery may follow sooner or later, ac- 

 cording to the severity of the injury to the nerves — the cur- 

 able form. 



Fig. 253 — Horse Affected with Brachial Paralysis in Its Curable Form. 



Differentiation is not always possible at the onset, al- 

 though the former may be suspected when the patient suffers 

 considerable pain, is perfectly helpless, cannot be induced 

 to move even when punished, and the leg is entirely help- 

 less. When, after four weeks, there is no amelioration of 

 the paralysis, the muscles have atrophied, and the patient 

 has become emaciated from pain and discomfort, the 

 diagnosis of brachial paralysis with fracture of the first rib 

 may then be announced. On the other hand, if the strength 

 of the leg is gradually restored after the second week it is 



