DIVISIONS OF THE CORD. 



547 









J 



I't'i.m extends forwards nearly to the centre of the 

 medulla, separating the nervous substance of the right and left 

 halves. Vessels of the posterior surface of the cord enter in the 

 septum. 



The lattml furrow (fig. 198, d) is a shallow groove along the lateral, 

 line of attachment of the fasciculi of the posterior roots. 



Between the posterior median and the lateral grooves another and pos- 

 slight furrow, the posterior intermediate, may be seen in the upper 

 part of the cord (fig. 198, e). 



DIVISIONS OF THE CORD. Each half of the cord between the The cord is 

 median su'ci is divided into two by 

 the lateral furrow (fig. 198, d) ; the 

 part in front of that groove and the 

 posterior roots of the nerves is called 

 the antero-lateral column (a) ; and the 

 part behind, the posterior column (6). 



The antero-lateral column (fig. 

 198, a) includes rather more than 

 two-thirds of the half of the cord. 

 extending backwards to the posterior 



roots of the nerves, and gives attach- FlQ 198- _ A SKCTION OP THE 

 ment to the anterior nerve roots (&). 

 This part of the cord is sometimes de- 

 scribed as consisting of anterior and 

 lateral columns, the two being sepa- 

 rated by the anterior roots of the 

 nerves. 



The posterior column (fig. 198, 6) is 

 situate between the lateral furrow (rf), 

 with the posterior roots of the 

 nerves, and the posterior median 

 septum. In the cervical region, the 

 posterior intermediate sulcus(e) marks 

 off a small inner portion, which is 

 named the posterior median column(c} ; 

 and the remainder is then distin- 



guished as the posterior external *>y white fibres. 



7 ,,. li. Grey transverse commissure, 



column (o). and if canal of the cord in it> 



A narrow central piece, the com- j. Posterior, and k. anterior and com- 

 missure of the cord, unites the halves root of a nerve entering the grey missure. 

 between the anterior median fissure 

 and the posterior median septum. 



COMPOSITION OF THE CORD (fig. 198). Horizontal sections ofcordcon- 

 the cord in the cervical, dorsal, and lumbar regions, show more dis- 

 tinctly its division into halves, with the commissural or connecting ' natter - 

 piece between them, and the varying proportion of its grey and 

 white matter in the different parts. The cuts demonstrate the 

 existence of a mass of grey matter in the interior, which is arranged 

 in the form of two crescents (one in each half), united by a cross 

 piece, and surrounded by white substance. 



N X 2 



SPINAL CORD IN THE CERVICAL 

 REGION TO SHOW ITS COMPOSI- 

 TION AND DIVISIONS. IN THE 



MIDDLE LINE BELOW IS THE 

 ANTERIOR MEDIAN FISSURE, 

 AND ABOVE ARE THE POSTERIOR 

 MEDIAN GROOVE AND SEPTUM. 



posterior 



d. The lateral sulcus. column, 



e. The posterior intermediate 

 sulcus. 



Columns : 



if. Antero-lateral. with median 



b. Posterior external. and external 



c. Posterior median. 



Composition : 

 g. Grey crescent, surrounded 



crescent - 



