556 



GENERAL ANATOMY OF THE NERVOUS SYSTEM. 



-B 



matter of the spinal marrow, where they appear to end ; 

 another portion of the fibres of the same nerves, turning 

 upwards, and constituting a part of the spinal cord in its 

 course to the brain. This arrangement of the nerves in the 

 medulla, see fig. 221, Mr. Grainger observes, he demonstrated 

 Fig. 218. to the entire satisfaction of 



Professors Arnold, Bur- 

 dach, and Sir C. Bell. 

 The same thing has also 

 been nearly conclusively- 

 shown to exist in regard 

 to the encephalic nerves, 

 the principal difference 

 between which and the 

 spinal nerves is the origin 

 of the former from a differ- 

 ent portion of cineritious 

 matter, and their not so 

 usually having their fibres 

 of sensation, and their 

 fibres of motion rolled up 

 into a common fasciculus, 

 as is the case with the 

 spinal nerves, but running 

 out to their destination 

 "" v j mainly as distinct nerves, 

 either of motion or sensation. The fibres of the anterior and 

 posterior roots of the spinal nerves, that terminate in the spinal 

 marrow, are called by Hall and Grainger, the true spinal, 

 excito-motory , or incident and reflex spinal nerves, and are con- 

 sidered to derive their origin and power from the cineritious 

 matter of the spine in which they arise, and to have functions 

 as much involuntary and organic, as any of those which belong 

 to the sympathetic nervous system. Those which pass upwards 

 into the brain are called the cerebral sensiferous and cerebral 

 motorial nerves. 

 Fig. 218, is a plan of the spinal cord from Grainger, intended 



