SPINAL COED. 



185- 



SPINAL COED. 



The membranes covering the cord will be discussed later. 



The spinal cord is composed of gray (cellular) and white (fibrous) 

 nerve matter, and serves as a medium of communication between the 

 brain and peripheral nerve apparatus. The arrangement of its sev- 

 eral parts will be best understood by the study of a transverse section,, 

 of which Fig. 121 is a diagrammatic representation. 



The gray substance occupies the central portions of the structure,. 



FIG. 121. DIAGRAM. CERVICAL SPINAL CORD IN TRANSVERSE SECTION. 



A. Anterior median fissure. 



B. Posterior median fissure. 



C. Anterior cornu gray substance. 



D. Posterior gray cornu. 



E. Point of emergence of anterior root of spinal nerve. 



F. Posterior root of spinal nerve. 



G. White commissure. 



H. Anterior gray commissure. 

 I. Posterior gray commissure. 

 J. Substantia gelatinosa. 



The tracts which are named on the diagram have no definite boundaries histologically. 

 They are physiological areas. 



