THE CAT. 



[CHAP. ix. 



dorsally, of which the first or "anterior* median fissure" is the 

 more distinct, and a process of the pia mater is prolonged into it, 

 which is not the case as regards the posterior median fissure. 



Each lateral half of the spinal cord is also marked by two longi- 



Fig. 121 DIFFERENT VIEWS OF A PORTION OF THE SPINAL CORD FROM THE CERVICAL 

 REG: ION, WITH THE ROOTS OF THE NERVES, ENLARGED (ALLKN THOMSON). 



In A the ventral or anterior surface is shown, 

 the anterior nerve-root of the right side 

 being divided ; in P>, a view of the light side 

 is given ; in C, the anterior or upper surface 

 is shown ; inJD, the nerve-roots and ganglion 

 are shown from below. 



1. 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 pos- 



terior roots are seen to sink. 



5. Anterior roots passing the ganglion. 

 5'. In A the anterior root divided. 



0. 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 

 I) to be derived in part from the anterior 

 and in part from the posterior root. 



tudinal furrows, of which the posterior, or posterior lateral fissure, is 

 far the more distinct. These furrows serve to define what are called 

 the "columns" which make up the cord each lateral half of it 

 being divided into an anterior, a lateral, and a posterior column. 

 Nervous fibres (the roots of the spinal nerves) pass out at the anterior 

 and posterior lateral furrows. 



As the nerves which so pass out traverse the intervertebral 

 foramina of the spinal column, and as the spinal cord stops (as has 

 been said) much short of the hinder termination of the vertebral 

 neural canal, it comes to pass that the nerves which pass out at the 

 sacral foramina have run back for a longer or shorter distance within 



* The terms "anterior" and "pos- 

 terior " refer to human anatomy, which 

 originated these names applicable to 



man with his upright attitude, but 

 unfortunate as applied to a quadruped 

 like the cat. 



