Chap. XVI.] 



THE SPINAL CORD. 



129 



differs in the different regions, and this difference 

 is chiefly brought about by the length and thickness 

 of the grey commissure. In a section through the 

 cervical region the grey commissure is thick and 

 short; in the dorsal region it becomes thinner and 



a 



Fig. 82. Transverse Section through the Spinal Cord of Calf. 



a, Pia mater ; 5, prolongation of pia mater into the anterior longitudinal fissure ; 

 c. posterior longitudinal fissure; d, anterior column of white matter; e, 

 lateral column of same ; /, posterior column of same : g, anterior white 

 commissure ; h, central canal ; i, anterior horn of grey matter ; j, posterior 

 horn of grey matter ; k, anterior nerve roots ; I, posterior nerve roots. 



longer ; and in the lumbar region it is comparatively 

 very thin and long. Besides this, of course the relative 

 proportions of grey and white matter, as mentioned 

 before, indicate the region from which the particular 

 part of the cord has been obtained. In the lower 

 J 



