9?6 THE CENTRAL NERVOUS SYSTEM 



nected with the muscular coat of the bloodvessels. The rate or 

 depth of the respiratory movements will alter in response to a change 

 of activity in the other, because it is connected with muscles which 

 can act upon the chest-walls. 



Experiments on the anastomosis of nerves afford a very interest- 

 ing illustration of the determining influence of their peripheral con- 

 nections on the function of nerve-fibres. It has, in fact, been 

 shown that the central end of any efferent somatic fibre i.e., any 

 fibre running from the central nervous system and ending in 

 striated muscle can make functional connection with the peri- 

 pheral end of any other efferent fibre of the same class, whatever 

 be the normal actions produced by the two fibres. Advantage has 

 been taken of this in surgery. For instance, in a case of severe 

 facial (motor) tic the facial nerve was divided, and its peripheral 

 end united with a portion of the fibres of the spinal accessory. The 

 voluntary movements of the face, after regeneration had occurred, 

 were normally carried out through impulses descending the spinal 

 accessory. In cases of local paralysis, due to destruction of anterior 

 horn-cells (anterior poliomyelitis), restoration of movement has also 

 been obtained by connecting the motor nerve of the paralyzed muscles 

 to a portion of a nerve coming off from an uninjured region of the 

 cord But the possibilities of this procedure have been exaggerated 



By such operations it has been possible to transpose motor areas 

 on the cerebral cortex associated with the flexion and extension 

 of a particular joint, so that the part of the cortex which originally 

 caused flexion after the nerve anastomosis causes extension, and 

 vice versa. When the nerves supplying a group of muscles of the 

 dog's fore-limb are eliminated, the nerves of the antagonistic group 

 may be used to supply both groups, and co-ordinated movements 

 may be restored, although this does not occur so rapidly as when 

 the nerves supplying the two groups are simply cut and cross- 

 sutured (Kennedy). However, the limitations of this method 

 ought to be recognized. Before any anastomosis of nerves can be 

 made, good fibres must first be destroyed. Under favourable cir- 

 cumstances these may all regenerate and find their way to the struc- 

 tures they are intended to innervate. When regeneration is com- 

 plete, the number of fibres capable of functioning will at best be the 

 same as before the operation, and may easily be considerably less. 

 The benefit, whatever it is, will be associated solely with the re- 

 distribution of the fibres. There is reason to think that the closer 

 to the cell of origin a nerve is injured or divided, the less is the chance 

 of restoration, and Feiss has found that after lesions in the cord 

 or the spinal roots neither the anatomical pattern of the affected 

 nerves nor their functional power is much affected by subsequent 

 nerve anastomosis. 



The central end of any efferent somatic fibre can also make 



