30 LABORATORY OUTLINE OF NEUROLOGY 



V and VII. The trigeminus and facialis nerves are so inti- 

 mately united that microscopic methods are required for their 

 separation. In Figs. 2 and 3 they are drawn very diagrammat- 

 ically after slight dissection and separation of the roots and gan- 

 glia. Their true composition is shown in Fig. 5. The two upper 

 (more rostral) roots of the complex are the sensory and motor V; 

 the lower ones belong to VII. The sensory V root receives its 

 fibers from the skin of the whole head in front of the gill region. 

 The motor V root supplies the jaw muscles; the motor VII root 

 those of the hyoid arch. The sensory VII root (nervus inter- 

 medius, or portio intermedia of Wrisberg) receives most of 

 its fibers from taste-buds and the mucous lining of the mouth. 

 The lateral line roots which enter the brain in front of 

 the ear are usually named as parts of the VII nerve; see 

 Section 18. 



VIII. N. acusticus. From the labyrinth of the ear to the 

 acoustico-lateral area of the medulla oblongata. The cochlear 

 ramus is absent or rudimentary. A small sensory spot in the 

 saccule, the lagena, is regarded as the organ from which the 

 cochlear sense organ (spiral organ) of mammals has been differ- 

 entiated; its nerve, accordingly, is homologous with the cochlear 

 nerve of man. 



IX. N. glossopharyngeus. Arises from the oblongata by 

 three roots, two sensory and one motor, passes under the mem- 

 branous labyrinth of the ear and forks around the first gill cleft. 

 It contains visceral sensory and visceral motor fibers for the 

 innervation of the first gill and also a small lateral line com- 

 ponent (r. supratemporalis IX, Figs. 4 and 5). 



X. N. vagus. Arises from the oblongata by several roots 

 which form a large trunk from which arise branchial rami to 

 fork around the second to fifth gill clefts (visceral motor and 

 visceral sensory) ; also r. visceralis vagi for the viscera of the 

 body cavity farther back (esophagus, stomach, etc.). The r. 

 dorsalis vagi contains general cutaneous fibers for the skin be- 

 hind the internal ear (r. auricularis vagi) and also lateral line 

 fibers for part of the main lateral canal. The r. lateralis vagi 

 supplies the lateral canal behind the region reached by the r. 

 dorsalis. The r. supratemporalis vagi supplies the anterior end 

 of the lateral canal and the supratemporal canal. All lateral 



