1^x8 



A MANUAL OF ANATOMY 



comu posterioris. It contains a small amount of neuroglia, and 

 numerous nerve-cells. The portion adjoining the grey commissure, 

 which is slightly constricted, is called the cervix co^ynu, and the 

 portion contiguous to the cervix, which is slightly enlarged, is called 

 the caput comu. The part between the two cornua is called the body. 

 About the centre of the concavity of the body crescent the grey 

 matter projects outwards into the lateral column in the form of 

 processes arranged in a reticular manner and enclosing white 

 matter. This network is called the processus reticularis, and it is 

 most conspicuous in the cervical region. In the thoracic region, 

 more particularly in its upper part, the grey matter of each crescent 

 forms a triangular projection, which extends outwards for a short 

 distance immediately in front of the processus reticularis, and 

 adjacent to the junction of the anterior cornu with the grey com- 



Central Canal 

 Anterior Nerve-Root , 1 Mesial Group of Motor Cells 



Anterior Cornu 



Lateral Cornu 



Posterior 

 Posterior 



Lateral Group of Motor Cells 



Cells of Lateral 

 Cornu 



Clarke's Dorsal 

 Nucleus 



bstantia Gelatinosa 

 Rolandi 



Fig. S51. — Transverse Section of the Spinal Cord in the Upper 

 Thoracic Region, showing the Arrangement of the Grey Matter 

 AND Cells (Semi-diagrammatic) (after Poirier). 



missure. This projection is variously known as the lateral cornu, 

 the intermedio-lateral tract of Lockhart Clarke, or the intermediate 

 process of Gowers. When followed into the lower cervical and into 

 the lumbar regions it blends with the anterior cornu, the thickness 

 of which it increases, but it is again present above the level of the 

 fourth cervical vertebra. 



The grey matter varies in amount in different parts of the cord. 

 It is present in largest quantity in the lumbar enlargement, where 

 the large nerve-trunks for the lower limbs arise, and next to this 

 in the cervical enlargement, where the large nerve-trunks for the 

 upper limbs arise. 



The cornua of the crescents of grey matter vary in shape in 

 different regions. In the cervical region the anterior cornua are 

 short, broad, and blunt, and the posterior cornua are long, narrow, 



