552 H. W. NOREIS AND SALLY P. HUGHES 



THE FOURTH, FIFTH, AND SIXTH SPINAL NERVES 



Beginning with the fourth spinal nerve, there are marked 

 changes in distribution. The main ventral ramus lacks any 

 important branch to the rectus subvertebralis musculature, and, 

 after emerging from the axial trunk muscles, gives off a cutane- 

 ous branch which passes dorsolaterally out over the dorsal bor- 

 der of the sphincter colli muscle to the skin mediolaterally (vcl.). 



THE SYMPATHETIC CHAIN 



The main sympathetic trunk in Herpele begins anteriorly by 

 the union of two branches which arise, one from the lateral bor- 

 der of the posterior tip of the Gasserian ganglion and the other 

 from the ventrolateral border of the geniculate ganglion (fig. 

 27, sy.V, sy.VII). The common trunk formed by these two 

 nerves soon becomes associated with the hyomandibular trunk 

 of the facialis, and by most observers has been considered as a 

 part, of the latter (fig. 29, sij., VII; also fig. 44,). In some 

 places the sympathetic and the facialis are bound together in 

 one trunk, but the non-medullated character of the fibers of the 

 sympathetic makes its recognition easy. The s>anpathetic 

 trunk accompanies the hyomandibular (or ramus jugularis, more 

 posteriorly) in its course posteriorly around the lateral border of 

 the ear capsule. At the level of the exit of the IX-X nerves, 

 the sympathetic has separated from the jugularis (fig. 32) and 

 approached very closely to the IX-X trunk, running parallel 

 with and along the ventral border of the latter to a point slightly 

 posterior to the trunk ganglion of the vagus (figs. 34, 38). Thence 

 the vagus drops ventrally around the lateral border of the sym- 

 pathetic and is thenceforth ventral and lateral to the latter 

 (figs. 39, 40). The two trunks continue in this parallel course 

 until the vagus curves ventrally to its distribution into its chief 

 terminal branches. At the level of the posterior third of the 

 trunk ganglion of the vagus, the sympathetic enters the first 

 great sympathetic ganghon (figs. 34, 44, gsy.l). Farther 

 posteriorly, between the levels of the second and third spinal 

 nerves, is a second still larger sympathetic ganglion (figs. 39, 



