243 THE NERVOUS SYSTEM 



Functions of the Spinal Cord. These are (i) conduc- 

 tions, (2) transference, (3) reflex action, (4) augmenta- 

 tion, (5) coordination, (6) inhibition of reflex acts, (7) 

 special centers (Collin and Rockwell, modified). 



i.* Conduction. This has been referred to in discussing 

 the white columns of the cord. This function makes it pos- 

 sible for the brain to receive impressions from and send im- 

 pulses to the periphery. It is to be remembered that most of 

 these impressions and impulses are interrupted by spinal 

 nerve cells in their passage between brain and periphery. 



2. Transference. An impression reaching the gray mat- 

 ter of the cord may be transferred (not as in typical reflex 

 action) so as to be felt in an entirely different region from 

 that in which the irritation takes place. Hip joint disease 

 often gives pain in the knee alone. 



3. Renex Action. The cord may act as a center without 

 the cooperation of the brain. Indeed, by no means do mus- 

 cular movements cease immediately on removal of the en- 

 cephalon if the cord and its nerves be left intact. An ani- 

 mal so mutilated possesses no sensation or volition, but for a 

 time the sensory nerves will continue to convey impressions 

 and the motor nerves impulses. Under these conditions im- 

 pressions (as of heat) are conveyed to the cord by the affer- 

 ent nerves ; the gray matter of the cord receives the impres- 

 sions and generates motor force which is sent out through 

 the corresponding efferent nerves, and movements result. 

 This is reflex action. The impression is reflected through 

 the cord and manifested in motion without the intervention 

 of sensation or volition. Reference to Figs. 77 and 80 

 shows how reflex action is anatomically possible through the 

 cord connections. Typical reflex action requires anatomic- 

 ally (i) something to produce an impression, (2) a nerve 

 terminal to receive it, (3) a centripetal fiber to convey it, 

 (4) a center to receive and transform it, (5) a centrifugal 

 fiber to convey it to the periphery, and (6) a muscle to con- 

 tract. This remark applies to reflex action connected with 



