NERVOUS SYSTEM. 65 



of the first are situated in the spinal ganglia, and the nerves 

 terminate in the dorsal horn. The ganglion cells of the somatic 

 motor nerves lie in the ventral horn, and the nerves leave by the 

 ventral roots. The internal relations of the visceral system are 

 not so evident ; but both are possibly related to the lateral horn 

 region, the visceral sensory nerves, whose centres in the trunk 

 region are in the sympathetic ganglia, entering by the dorsal 

 roots, while the visceral motor nerves leave by both dorsal and 

 ventral roots (not proved for mammals) 



rr red 



plv-.- 



FIG. 65. Diagram of the sensory components in the cranial nerves in Menidia, 

 after C. J. Herrick. General cutaneous component white; communis (visceral) 

 dotted; lateralis black; the outline of the brain shaded, b, gill clefts; bg, branchial 

 ganglia of the vagus, the last containing the ganglion of the ramus intestinalis ; 

 ct, pre-trematic branch (chorda tympani) of facialis ; dl, dorsal lateral line ganglion 

 of the facialis ; fc, fasciculus communis ; gg, Gasserian ganglion ; gn, geniculate 

 ganglion; /, general cutaneous (jugular) ganglion of the vagus; Iv, lobus vagi; w 5 , 

 os 1 , ophthalmicus superficial of fifth and seventh nerves; red, ramus cutaneus 

 dorsalis of vagus ; rlv, ramus lateralis of the vagus ; rot, ramus oticus ; rp, ramus 

 palatinus of the facialis ; rr, ramus recurrens of the facialis ; s, ramus supratempora- 

 lis of the vagus; spv, spinal V tract (ascending root of the trigeminal); ta, tuber 

 acusticum ; thm, hyomandibular trunk; tm, inferior trunk, containing the rami 

 maxillaris and mandibularis of the trigeminal, the buccalis of the facial and com- 

 munis fibres; vl, ventral lateral line ganglion of the facialis; /, olfactory; //, optic; 

 VIII, auditory; IX, glossopharyngeal. 



