AFFERENT, OR SENSORY PATHS. 377 



II. AFFERENT, OR SENSORY PATHS. 



The sensory paths conduct two varieties of impulses, viz., 

 general and special. The impulses originate in the end-organs 

 of the cerebral and spinal nerves, and by those nerves are con- 

 veyed to the cerebro-spinal axis, through which they reach the 

 proper cortical area in the cerebrum. 



i. General Sensations. 



General sensation is the function of the sense of touch. This 

 sense has four important subdivisions the tactile sense, mus- 

 cular sense, pain sense, and temperature sense. Stereognosis is 

 only an associated interpretation of all the impulses of the sense 

 of touch and not a subdivision of it. Tactile sensations appear 

 to be most elemental and, according to Spiller and Mills, may be 

 conducted by all common sensory nerve fibers. Other common 

 sensations seem to require some specialization, as yet not under- 

 stood, in their conducting media; and pain and temperature im- 

 pulses pursue a path entirely distinct from that followed by im- 

 pressions of the muscular sense. In giving the common sensory 

 tracings, the following classification will be adhered to, though 

 conclusive evidence of certain points in it is still lacking. 



I. Paths conducting impulses of the muscular and tactile 

 senses, chiefly, from muscles, tendons, joint surfaces, and the 

 skin. Spinal and cerebral (Fig. 107). 



II. Paths carrying impulses of the muscular and tactile sen- 

 ses, chiefly from viscera (?) (Fig. 107). 



III. Paths conveying pain, temperature, and tactile impulses. 

 Spinal and cerebral (Fig. 108). 



I. PATHS TRANSMITTING IMPULSES OF THE MUS- 

 CULAR AND TACTILE SENSES, chiefly, from muscles, tendons, 

 ligaments, joint surfaces and the skin. 



Through Posterior Column and Fasciculi Gracilis et Cu- 

 neatus (Fig. 107). Impulses originating in the end-organs of the 

 spinal nerves traverse the dendrites of the spinal ganglion neurones 

 (Cajal), the cell-bodies in the ganglia, and then the axones of the 

 same. They enter the cord through the posterior roots of the 



