570 



THE SPINAL XERVES. 



The anterior roots of the spinal nerves are, as 'will be inferred from 

 what has been already stated, the smaller of the two ; they are devoid 

 of ganglionic enlargement, and their fibres are collected into two 

 bundles near the intervertebral ganglion, as in the posterior root. 



Size. — The roots of the upper cervical nerves are smaller than those 

 of the lower nerves, the first being much the smallest. The posterior 

 roots of these nerves exceed the anterior in size more than m the otlier 

 spinal nerves, and they are likewise composed of fasciculi which are 

 considerably larger than those of the anterior roots. 



Fig. 352. — Different Fig. 352. 



Views of a portion op 

 THE Spinal Cord from 

 THE Cervical Region 

 •WITH the Roots op 

 the Nerves. Slightly 

 enlarged. (A. T.) 



In A, the anterior sur- 

 face 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, tlie upper 

 surface is shown ; in D, 

 the nerve-roots and gan- 

 glion are shown from 

 below. 1, the anterior 

 median lissure ; 2, pos- 

 terior median fissure ; 3, 

 anterior lateral depres- 

 sion, over which the ante- 

 rior nerve-roots are seen 

 to spread ; 4, posterior 

 lateral groove, into which 

 the postei'ior roots are 

 seen to sink ; 5, anterior 

 roots passing the ganglion ; 

 5', in A. the anterior root 



divided ; G, the posterior roots, the fibres of which enter the ganglion, C ; 7, the uniteJ 

 or compound nerve ; 7', the posterior primary branch seen in A and D to be derived iu 

 part from the anterior and in part from the posterior root. 



The roots of the dorsal nerves, exception being made of the first, which 

 resembles the lowest cervical nerves and is associated with them in a 

 part of its distribution, are of small size, and vary but slightly, or not 

 at all, from the second to the last. The fasciculi of both roots are 

 thinly _ strewed over the spinal cord, and are slender, those of the 

 posterior exceeding in thickness those of the anterior root in only a 

 small degree. 



The roots of the lower lumbar, and of the upper sacral nerves, are the 

 largest of all the spinal nerves ; those of the lowest sacral and of the 

 coccygeal nerve are, on the other hand, the slenderest. All these 

 nerves are crowded together round the lower end of the cord. Of 

 these nerves the anterior roots are the smaller, but the disproportion 

 between the anterior and posterior roots is not so great as in the 

 cervical nerves. 



Length of the nerves in the spinal canal. — The place at 

 which the roots of the upper cervical nerves are connected with the 



