258 



INNERVATION. 



[CHAP. x. 



the nerves have been carefully removed, their points of emergence 

 are indicated by two series of foramina in linear sequence on each 

 side ; but there is no appearance of fissures in those situations. The 

 roots of the nerves penetrate the substance of the cord, and are 

 chiefly, if not entirely, connected with the antero-lateral columns. 



The fibrous matter of the cord consists of some fibres which pass 

 in a longitudinal direction, which are chiefly superficial or contained 

 in the posterior columns, and of others which are oblique or trans- 

 verse, and are found in the antero-lateral columns, or in the white 

 commissure, which is wholly composed of such fibres. Among the 

 elements of the gray matter fibres are found in great numbers, the 

 direction of which is probably for the most part oblique or trans- 

 verse, as considerable portions of them may be seen so running, 

 when a piece of gray matter, cut transversely, is examined under 

 the microscope. The gray matter of the cord is disposed in two 

 longitudinal columns, the shape of which in the several regions of 

 the cord is represented in the above transverse sections (fig. 66). 

 These columns extend from the lower part of the medulla oblon- 

 gata, with the gray matter of which they are continuous. The 

 aspect of their surfaces is outwards and inwards. That which 

 looks inwards is convex, and is united to the corresponding sur- 

 face of the opposite side by the gray commissure, which is a ver- 

 tical plane, with surfaces looking directly forwards and backwards. 

 At the inferior extremity of the cord these columns gradually 



per to a point, and coale 

 as the white matter dimi- 

 nishes. 



Caudate and spherical vesi- 

 cles, imbedded in their usi 

 granular matrix, exist in the 

 gray matter of the cord at 

 situations, in the horns as we 

 as in the commissure, 

 caudate vesicles are m< 

 numerous and distinct in tl 

 anterior horn, and at the 

 root of the posterior one 



Transverse section of human spinal cord, close to the rnr, /? , -i 



third and fourth cervical nerves ; magnified ten diameters, ine TCSt OI tnC pOSterN 



(from Stilling) :/. Posterior columns, i i. Gelatinous sub- i ,r i , 



stance of the posterior horn. k. Posterior root 1. Sup- nom and trie gClatmOl 



posed anterior roots, a. Anterior fissure, c. Posterior , r^j. 11 



fissure. 6. Gray commissure, in which a canal is contained, SUDStanCC resemble VC1 



which, according to these writers, extends through the _i__-i_ -,<-., n j.,,, lrt l, 



length of the cord. g. Anterior horn of gray matter con- ClOSCly in Structure the graj 



taining caudate vesicles, e. Antero-lateral column (from ^^ Qf ^ convoluti()1 



