STRUCTURE OF THE SPINAL CORD. 



493 



the most difficult things in structural anatomy to determine 

 the course of individual nerve-fibres, or even of fasciculi 

 of fibres, through even a short distance of the spinal cord ; 

 and it is only by the examination of transverse and longi- 

 tudinal sections through the substance of the cord, such 

 as those so successfully made by Mr. Lockhart Clarke, that 

 we can obtain anything like a correct idea of the direction 

 Fig. 134* 



* Fig. 134. 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 anterior 

 nerve-root of the 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 gang- 

 lion 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 ; 7', 

 the posterior primary branch, seen in A and D to be derived in part from 

 the anterior and in part from the posterior root. 



