THE NERVOUS SYSTEM 



509 



CEREBELUDM 



ANAL3 /O-/ 

 COCHLEA 



•Sensory 

 Patla 



tioioc 

 Paths 



Motor Fibers from 



Higher Arc3 to Alt 



4 tegmental Levels 



Long Sensory Fibers 



to Higher Arcs 

 via. .Sensory Paths 



Sensory 



Nerve Endings 



in Shin 



Fig. 426.— Schematic diagram showing the nature of the activities carried out in various parts 

 of the central nervous system. Arc 7. Voluntary and Inhibitory Control. Choice ot response 

 based on memory of past experience. (Via pyramidal tract.) Arc 6. Automatic associated control 

 of complex muscular actions. (Via striato-rubro-spinal tract.) Arc 5- a. Auditory Reflexes, e.g.. 

 Automatic response to sudden noise. 6, Visual reflexes, e.g., Automatic response to blinding Hash ot 

 light. (Both via tecto-spinal tract.) Arc 4. Synergic Control. Automatic coordinating control ot 

 muscular actions. (Via rubro-spinal tract.) Arc 3- Equilibratory Control. Automatic balancing 

 reactions. (Via vestibulo-spinal tract.) Arc 2. Intersegmental Reflex. Impulse carried by 

 association neurones to neighboring segments causing coordinated response of muscles m several 

 segments. Arc i. Intrasegmental Reflex. Response limited to segment stimulated, (from 

 Patten's "Embryology of the Pig.") 



