STRUCTUKE OF THE SPINAL COED. 



491 



the lateral and posterior column arise the posterior roots 

 of the same : a pair of roots on each side corresponding to 

 each vertebra (fig. 141). 



The fibrous part of the cord contains continuations of the 

 innumerable fibres of the spinal nerves issuing from it, or 

 entering it ; but it is, probably, not formed of them exclu- 



* Fig. 141. Different views of a portion of the spinal cord from the- 

 cervical region, with the roots of the nerves slightly enlarged (from 

 Quain). In A, the anterior surface of the specimen is shown ; the an- 

 terior nerve-root of its right side being divided ; in B, a view of the 

 right side is given ; in c, the upper surface is shown ; in D, the nerve- 

 roots and ganglion are shown from below. I. the anterior median 

 fissure ; 2, posterior median fissure ; 3, anterior lateral depression, over 

 which the anterior nerve-roots are seen to spread ; 4, posterior lateral 

 groove, into which the posterior roots are seen to sink ; 5, anterior 

 roots passing the ganglion ; 5', in A, the anterior root divided ; 6, the 

 posterior roots, the fibres of which pass into the ganglion 6' ; 7, the 

 united or compound nerve ; J r , the posterior primary branch, seen in 

 A and i> to be derived in part from the anterior and in part from the 

 posterior root. 



