THE SPINAL CORD AND ITS NERVES 



141 



physiologically into tracts. The latter are the really significant 

 units in the analysis of the cord. Peripherally, the spinal nerves 

 divide into deep and superficial branches, and the latter contain, 



cerebral 



cortex 



trUjeminal lemniscus 



sKin 



medial lemniscus 



nucleus of dorsal 



funiculus 



spinal lemniscus 



ventral pyramidal 

 tract 



dorsal funtcufus 

 lateral pyramidal tract 



spinal ganglion 

 sKin 



muscle 



Fig. 64. Diagram of the chief connections between the spinal cord and 

 the cerebral cortex. The spinal lemniscus complex carries the ascending 

 exteroceptive systems (touch, temperature, and pain) ; the dorsal funiculus 

 and medial lemniscus complex carries chiefly ascending proprioceptive sys- 

 tems (a nerve of muscle sense is the only member of this group included 

 in the drawing) . The diagram also includes the sensory path from the skin 

 of the head to the cerebral cortex through the V cranial nerve (trigeminus) 

 and the trigeminal lemniscus (p. 157). The pyramidal tract (tractus cpr- 

 tico-spinalis) is the common descending motor path for both exteroceptive 

 and proprioceptive nervous impulses from the cerebral cortex. 



