254 PBINOIPLES OF VETEBINABI SUKGERY 



DISEASES OF NERVES. 

 Paralysis. 



What do you understand by paralysis of a nerve ? 



Complete cessation of the functional activity of the nerf ew 

 What do you understand hy paresis ? 



Impaired functional activity of a nerve, 



According to the origin, what forms of paralysis are recog~ 

 nised ? 

 When originating in the brain, it is termed cerebral paral- 

 ysis ; when in the spinal cord, it is called spinal paralysis j 

 "when originating in a nerve trunk — that is, the nerve after it 

 leaves the spinal canal — it is known as peripheral paralysis. 



According to the extent of the paralysed area, what forms of 

 paralysis are given ? 

 In hemiplegia, one side of the body is paralyzed ; in 

 paraplegia, both sides are affected ; in monoplegia, a muscle, 

 or set of muscles, or a single leg, is paralyzed. 



What psychological facts are of special interest in nerve 

 paralysis ? 

 A voluntary contraction of a muscle requires, first, & 

 motor impulse generated in the psychomotoric centers in th& 

 gray matter of the cerebral cortex ; this is conducted dowur 

 ■ward by the motor fibers, which decussate at the medulla 

 oblongata ; that is, those fibers originating on the right side 

 cross over to the left side and vice versa (which explains the 

 fact that a hemiplegia, for instance, affecting the right side 

 of the body finds its active cause in some pathological state of 

 the left side of the brain). After decussating, the motor- 



