270 NERVE COMPONENTS OF BONY FISHES. 



5. — TJie Facialis. 



There are four roots and three components, as dia- 

 gramed in Fig. II. The motor root arises from the 

 motor VII nucleus and is related in passing out to the 

 fasciculus longitudinalis dorsalis. It runs out under the 

 spinal V tract and the VIII root, while the other VII 

 roots pass over these structures. It runs into the truncus 

 hyomandibularis and supplies the mm. levator operculi, 

 adductor operciili, adductor hyomandibularis, adductor 

 arcus palatini and hyo-hyoideus. These are viscero-motor 

 fibres like those from the nucleus ambiguus. 



The communis root enters the brain between the two 

 lateralis roots, arising in the geniculate ganglion and 

 forming the whole of the pre-auditory fasciculus com- 

 munis. From the geniculate ganglion fibres go out to 

 form the whole of the r. pre-trematicus VII for the 

 pseudobranch and the mucous lining of the mouth adja- 

 cent, and of the r. palatinus for the mucous lining and taste 

 buds of the roof of the mouth and of the r. lateralis acces- 

 sorius for special cutaneous sense organs. Other fibres 

 enter the truncus hyomandibularis and supply the mucosa 

 and taste buds of the lining of the mandible and lower 

 lip; others enter the r. maxillaris of the truncus infra- 

 orbitalis and supply taste buds of the upper lip; while 

 still others enter the truncus supra-orbitalis. 



The two lateralis roots terminate together in the tuber- 

 culum acusticum. The ventral one enters the truncus 

 hyomandibularis and supplies the organs of the operculo- 

 mandibular line. The dorsal one distributes its fibres to 

 the supra- and infra-orbital trunks for the organs of the 

 supra-orbital and infra-orbital lateral lines respectively. 



