068 



A TEXTBOOK OF PHYSIOLOGY 



The Tracts arising from the Posterior Root Ganglia, and passing 

 into the Cord (Posterior Columns) The Postero- Median Tract (of 

 Goll). The cell-stations are in the posterior root ganglia, especially 

 the sacral and lumbar. The fibres first enter the postero-lateral 

 column, and then pass into the postero-median, tying dorsally close 

 against the postero-median fissure (12, Fig. 395). They pass up to the 

 gracile nucleus situated at the junction of the cord with the spinal 

 bulb, giving off many collaterals on the way. 



Dentate nucleus 



S" f. 



r *" --4 



^"4^ 



Direct cerebellar- 



Part of Gower's tract 

 entering cerebrum by 

 superior cerebellar 

 peduncle 



Tactile 



Gracilis: cuneate nuclei 

 v Pain, heat, and co!d 



Tactile 

 (discrimination) 



Joint and 



muscle senses 

 (sense of position) 



f Jan-sensory recepto' 

 (Clarke's column) 



Deep sensation 

 Superficial sensation ' 



Fi3. 396. DIAGRAM TO ILLUJTRATB THE AFFERENT SYSTEMS TO CEREBRUM AHI> 



CEREBELLUM. (Mott.) 



Tactile receptor 

 Pain receptor 

 Heat receptor 

 Cold receptor 



ThePostero-Laleral Tract (ofBurdach). The fibres arise like the pre- 

 ceding and pass in a more external position, to end around the cells 

 of the cuneate nucleus at the base of the spinal bulb (13, Fig. 395). 



The Marginal Tract (of Lissauer) lies just external to the posterior 

 horn of grey matter. The fibres arise from cells in the posterior root 

 ganglia. They are very fine ascending fibres, which gradually form 



