604 



THE NERVOUS SYSTEM 



The ventral columns are also much increased in size by the addi- 

 tion of many fibers coming down from the medulla and cerebellum, 

 which place the nerve centers of the spinal cord in close relation with 

 those of the cranial nerves and with the association centers of the cere- 

 bellum. 



In addition to the large size of its white columns, a noticeable char- 

 acteristic of the upper cervical region is the prominence of its lateral 



horns of gray matter. 

 Just dorsal to the 

 lateral horns is also a 

 peculiar reticular for- 

 mation which results 

 from an invasion of 

 the adjacent portions 

 of the lateral white 

 columns by bands of 

 gray matter. The 

 gray matter thus 

 forms a coarse net- 

 work whose meshes 

 inclose isolated bun- 

 dles of longitudinal 

 nerve fibers. 



The ventral horn 



cells of this region are scarcely divisible into groups, but a large and 

 distinct cell group, the intermediolateral cell column, occupies the 

 so-called lateral horn. 



The nuclei of the upper cervical region innervate the skin and 

 muscles of the neck and shoulder, they also supply the diaphragm. The 

 nerve cells of this region not only supply the cervical spinal nerves, but 

 they also send root bundles to the spinal accessory or eleventh cerebral 

 nerve. 





FIG. 522. TRANSECTION OF THE SPINAL CORD OF A 

 CHILD, FOURTH CERVICAL SEGMENT. 



Weigert stain. X 7. 



THE CEREBELLUM 



The cerebellum consists of an irregular core of white substance, 

 the medulla, and a thick mantle of gray matter, the cortex. It com- 

 prises two hemispheres or lobes connected by a third lobe, the vermis. 

 Each lobe is a combination of lobules which include a variable number 

 of transverse convolutions or folia. Bach folium contains a medullary 



