NERVE REFLEXES 



295 



Summary 



The spinal nerves are distributed to all skeletal muscles and 

 integument except those of the front of the head, face, and chin. 

 Through sympathetic connections they also supply secreting cells 

 of glands and walls of viscera. 



FUNCTIONS OR PHYSIOLOGY OF THE SPINAL CORD 

 AND SPINAL NERVES 



The spinal cord is so intimately connected with the brain by 

 conducting fibers in the tracts, that it is impossible to explain all 

 of its functions without referring to the brain, but certain ones 



: sp.c. 



FIG. 190. DIAGRAM SHOWING THE STRUCTURES INVOLVED IN THE PRODUCTION OF 



REFLEX ACTIONS. (G. Bachman.) 



r.s., Receptive surface; af.n., afferent nerve; e.c., emissive or motor cells in the 

 anterior horn of the gray matter of the spinal cord, sp.c; ef.n., efferent nerves^ dis- 

 tributed to responsive organs, e.g., directly to skeletal muscles, sk.m., and indi- 

 rectly through the intermediation of sympathetic ganglia, sym. g., to blood-vessels, 

 b.v., and to glands, g. The nerves distributed to viscera are not represented. 



may be exercised independently, and a few of these will be con- 

 sidered briefly in this connection. 



The spinal cord a center for reflex action. This is one of the 

 most important of its functions and the simplest form of nerve 

 and muscle action. Acts which may be performed without 

 thinking of them are reflex, also those which are performed 

 independently of the will although with perfect consciousness. 



