ANATOMY AND PHYSIOLOGY OF THE SPINAL COED. 397 



terminates posteriorly in a pointed extremity, which is 

 continued by a mass of nervous trunks (Cauda Equinse). 

 Running along the supero-lateral aspect of each half of the 

 cord, is a third, though much shallower groove (supero- 

 lateral), corresponding to the points of origin of the superior 

 roots of the nerves, and dividing the inferior from the 

 superior column. In the middle of the inferior column is 

 a line formed by the exit of the motor roots of the nerves, 

 and which is sometimes made to signify a further division 

 into inferior and lateral columns. 



Fig. 210. Portion of the spinal cord showing its cut end. 1, Inferior longitudinal fissure; 

 2, superior longitudinal fissure ; 3, inferior columns; 4, line giving origin to the sensory 

 roots of the spinal nerves; 5, line of origin of the motor roots; 6, lateral columns; 7, 

 superior columns; 8, motor roots; 9, sensory roots ; 10, mixed nerve; 11, interrertebral 

 ganglion on the sensory roots, 



A transverse section of the cord reveals that it is com- 

 posed of white matter externally, and of grey internally. 

 The grey matter is arranged in the form of two crescent- 

 shaped masses, placed back to back, and joined to each 

 other by a transverse portion or commissure (grey commis- 

 sure). The horns, of grey matter, extending upwards from 

 the commissure, are longer but narrower than those which 

 project downwards. The former extend to the surface of 



