THE SPINAL CORD 665- 



The grey matter consists mainly of iierve cells and their 11011- 

 medullated processes ; the white matter of the axons, or medullated 

 nerve processes. The nerve-fibres in the spinal cord are devoid of 

 neurilemmal sheath. The neuroglia, the supporting tissue of the 

 cord, is intimately woven into the structure of the cord, particularly 

 of the grey matter. Round the central canal it forms the substantia 

 gelatinosa centralis, and around the head of each posterior horn 

 of grey matter is another collection of neuroglia, the substantia 

 gelatinosa Rolandi. 



FIG. 391. DIAGRAMMATIC SECTION FIG. 392. DIAGRAMMATIC SECTION OF 

 THROUGH SPINAL CORD is THORACIC SPINAL CORD THROUGH CERVICAL 

 KEGION. (Parsons and Wright.) ENLARGEMENT. (Parsons and Wright). 



Fi. 393. DIAGRAMMATIC SECTION OF SPINAL CORD THROUGH THE LUMBAR 

 ENLARGEMENT. , (Parsons and Wright.) 



The grey matter in each hah* of the cord is divided into a posterior 

 horn, a lateral horn, and an anterior horn. In it are various group* 

 of cells, the chief of which may be classified as 



1. Posterior horn cells. These are small multipolar cells, chiefly 

 of commissural function. 



2. Clarke's column of cells cells, more or less bipolar in form, 

 situated on the inner aspect of the posterior limb of grey matter, 

 near its junction with the connecting limb. From it axons pass into 

 the cerebellar tracts. 



3. Intermedio-lateral group a group of cells situated chiefly 

 in the lateral horn. From it axons pass out into the sympathetic 

 svstem. 



