179 



disturbed over approximately the same region (the temperature 

 disturbance involving the right side also). These symptoms 

 resulted from the destruction of all dorsal root fibers in the 

 affected area at the point of their entrance into the cord or of the 

 gray substance containing the terminals of these fibers, a purely 

 local effect. That the dorsal funiculus of the same side was also 

 involved is shown by symptoms of remote effects of the injury 

 in the left foot. All forms of exteroceptive sensibility (touch, 

 temperature, pain) were perfectly preserved in both legs, but the 

 left leg was devoid of proprioceptive sensibility, as shown by the 



Fig. 84. The loss of sensibility to pain resulting from a tumor in the cervical 

 region of the spinal cord. (After Head and Thompson.) 



loss of ability to appreciate the passive position or movement of 

 the leg and failure to discriminate two points with the compass 

 test. 



The intrinsic connections within the cord for spinal reflexes are undoubt- 

 edly very primitive. These are both exteroceptive and proprioceptive in 

 type (p. 132). We have seen that the ascending tracts between the spinal 

 cord and the brain fall into two groups: (1) The exteroceptive systems in 

 the spinal lemniscus, and (2) the proprioceptive systems in the dorsal funicu- 

 lus and medial lemniscus. Comparative anatomy shows that the spinal 

 lemniscus system is much older phylogenetically than the medial lemniscus 

 system. The fishes possess well-defined spino-tectal and spino-thalamic 

 tracts, but their dorsal funiculus possesses only the fasciculus propriua 



