THE SPINAL CORD 



79 



and forms a continuous fluted column, which is everywhere enclosed by the 

 white matter (Fig. 54). In cross-section it has the form of a letter H (Fig. 55). 

 There is a comma-shaped gray field in each lateral 

 half of the cord, and these are united across the 

 middle line by a transverse gray bar. The enlarged 

 anterior end of the comma has been known as the ven- 

 tral horn, the tapering posterior end as the dorsal 

 horn, and the transverse bar as the gray commissure. 

 But, when it is remembered that the gray substance 

 forms a continuous mass throughout the length of the 

 spinal cord, it will be seen that the term "column" 

 is more appropriate than "horn." The long gray mass 

 in either lateral half of the cord is convex medially and concave laterally. It 

 projects in a dorsolateral direction as the posterior column (columna posterior). 



As seen in a cross-section of the cervical cord, the posterior column is rela- 

 tively long and narrow and nearly reaches the dorsolateral sulcus (Fig. 55). 



Fig. 54. Diagram of gray 

 columns of spinal cord. 



Posterior intermediate sulcus and septum 



Collaterals from cuneate fasc. 

 

 Substantia gelaiinosa 



Posterolateral sulcus 

 \ 



Ceraix . 



Posterior column{ ^ if?" ~ \ 



Posterior median sulcus and septum 

 Fasciculus gracilis \ Posterior 

 \ Fasckulus cuneatus j fnniculus 



Dorsal root 



Dorsolateral fasciculus 

 (Lissauer) 

 lateral funiculus 



Reticular formation 



Posterior ...| 



com. 



Anterior ._S 

 gray com. 



Anterior - 

 white com. 

 Anterior' 

 column 



Anterolateral sulcus ' .7'^^ _ -Anterior funiculus 



A nterior median fissure 



Fig. 55. Section through seventh cervical segment of the spinal cord of a child. Pal-Weigert 



method. 



It presents a constricted portion known as the cervix, a pointed dorsal extrem- 

 ity or apex, and between the two an expanded part sometimes called the caput. 

 The apex consists largely of a special variety of gray substance, gelatinous in 



