TEE SPINAL NERVES. ROOTS. 



kept distinct from the seven which succeed, 

 as is taught in some schools, a nomenclature 

 is arrived at much less objectionable than that 

 which is most prevalent. A reference, however, 

 to development (p. 17) will remind the reader 

 that in the primordial vertebrae each spinal 

 nerve is originally situated above the rib and 

 transverse process belonging to the same seg- 

 ment; and it will become apparent that the 

 scientifically accurate nomenclature of nerves 

 might be rather to name each in accordance 

 with the number of the vertebra below it. Thus 

 the eighth cervical nerve would be called first 

 dorsal, and so on. 



Fig. 420. DIAGRAMMATIC OUTLINE OF THE ROOTS 

 AND FIRST PART OF THE SPINAL NERVES, 

 TOGETHER WI1H THE SYMPATHETIC CORD OF 



ONE SIDE. ^ 



The view is taken from before. In the upper 

 part of the figure the pons Varolii and medulla 

 oblongata are represented, and from V, to IX, 

 the roots of the several cranial nerves from the 

 trifacial to the hypoglossal are indicated. On 

 the left side C 1, is placed opposite the first cer- 

 vical or suboccipital nerve ; and the numbers 2 to 

 8 following below indicate the corresponding cer- 

 vical nerves; Br, indicates the brachial plexus ; 

 D 1, is placed opposite the intercostal part of the 

 first dorsal nerve, and the numbers 2 to 12 follow- 

 ing mark the corresponding dorsal nerves ; S 1, 

 the first lumbar nerve, and the numbers 2 to 5 

 following the remaining lumbar nerves; Cr, the 

 anterior crural, and o, the obturator nerve ; SI, 

 the first sacral, and the following numbers 2 to 5, 

 the remaining sacral nerves ; 6, the coccygeal 

 nerve; Sc, the great sciatic nerve; +, +, the 

 filum terrainale of the cord. 



On the right side of the figure the following 

 letters indicate parts of the sympathetic nerves ; 

 viz., a, the superior cervical ganglion, com- 

 municating with the upper cervical spinal nerves 

 and continued below in the great sympathetic 

 cord ; b, the middle cervical ganglion ; c, d, the 

 lower cervical ganglion united with the first 

 dorsal ; d', the eleventh dorsal ganglion ; from 

 the fifth to the ninth dorsal ganglia the origins 

 of the great splanchnic nerve are shown ; I, the 

 lowest dorsal or upper lumbar ganglion ; ss, the 

 upper sacral ganglion. In the whole extent of the 

 sympathetic cord, the twigs of union with the 

 spinal nerves are shown. 



Br 



Sometimes an additional coccygeal nerve 

 exists. Among seven cases which appear to 

 have been examined with great care, Professor 

 Schlemm (" Observat. Neurolagicee,'' Berolini, 

 1834) found two coccygeal nerves on each side 

 in one instance, and on one side in another 

 case. In all the rest there was only a single 

 coccygeal nerve on each side. 



Icr 



Sc 



