CHAPTER II. 

 DISEASES OF THE SPINAL CORD. 



General Considerations. — Functions of the Cord.— Briefly 

 stated, the functions of the spinal cord are: (a) A con- 

 ductor of nerve impulses from the intracranial nerve centers 

 to the periphery (skin and muscles), and from the periphery 

 to the center; (b) it is the great reflex center for muscular 

 coordination, and also contains in the anterior part special 

 reflex centers, which control respiration, the circulation and 

 deglutition, and in the lumbar portion are the centers for 

 defecation, micturition, etc. 



Examination.— The cord, like the brain, cannot be exam- 

 ined directly on account of its sheltered position within 

 the vertebral canal, but diseases of the cord can, in a general 

 way, be recognized by examining its functions. This is 

 done by essentially the same methods as are employed in 

 making an examination of the brain. 



It is difficult in some cases to differentiate between diseases 

 affecting the cord and those affecting the brain, but since 

 the cord is the seat of the reflex action, diseases affecting 

 it will, in many cases, destroy one or more of the reflex 

 arcs depending upon what particular part of the cord the 

 lesion occurs in. Therefore, all reflex action will be absent 

 or modified posterior to the lesion. This, together with 

 the fact that in diseases or lesions involving the cord alone 

 no psychic disturbances, as a rule, are present, will serve 

 to differentiate between them. 



MENINGOMYELITIS . 



Definition.— This is an inflammation of the spinal cord and 

 its covering membranes. It is quite common in the dog and 

 rabbit but rare in the other small animals. 



