CHAPTER XVII 

 THE SPINAL CORD 



Anatomy. The cylindrical spinal cord is composed of a column 

 of gray matter surrounded by a layer of white matter. In the cross- 

 section the gray substance has the form of an H. 



Each half of the white substance is divided by the gray substance 

 into three columns, the anterior, lateral, and posterior. From 

 between the anterior and the lateral columns the anterior roots of 

 the peripheral nerves proceed, and from between the lateral and 

 the posterior columns, the posterior roots. In each of the three 

 columns the following separate bundles may be discriminated (com- 

 pare Fig. 19) : 



1. In the anterior column : 



(a) Direct pyramidal tract. 

 () Anterior ground bundle. 



2. In the lateral column : 



(c-) Crossed pyramidal tract. 



(d) Direct cerebellar tract whose anterior part is called 



Gower's column. 

 (?) Lateral bundles. 



3. In the posterior column : 



(/") Coil's column. 

 () Burdach's column. 



The white matter contains medullated nerve fibres ; the gray 

 matter is chiefly composed of nerve cells. 



The functions of tJie spinal cord consist in conducting im- 

 pulses through fibres and cells. They may be divided into 

 three main groups : 



(1) The conduction of the impulses in the motor tracts 

 from the brain through the cord to the peripheral nerves. 



(2) The conduction of impulses from the peripheral 

 sensory nerves through the cord to the brain. 



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