I.] THE FROG. 29 



b. Postoral or Mandibular, passes between the 

 temporal and pterygoid muscles, over the articu- 

 lation of the mandible and along the inner face 

 of the latter, to the symphysis, giving off branches 

 to the integument, muscles, and tongue. 



6. Abducentes 



arise from the floor of the hind-brain and leave the 

 ventral surface of the medulla oblongata close to the 

 middle line. Each then unites so closely with the 

 Gasserian ganglion and with the orbito-nasal division 

 of the fifth as to appear to be only a subdivision 

 of the latter. Its fibres are distributed to the external 

 rectus and retractor bulbi muscles of the eye. 



7. The Faciales 



take their origin from the floor of the hind-brain, 

 behind the fifth and in common with the eighth; 

 and, leaving the hind-brain, enter into close con- 

 nexion with the Gasserian ganglion. Each then 

 divides into two branches, an anterior and a pos- 

 terior, 

 i. The anterior or palatine nerve; distributed to the 

 roof of the mouth and palate. 



This nerve is in anastomosis with the maxillary 

 branch of the fifth. 



ii. The posterior branch. It forks over the tympanic 

 cavity into two trunks ; a smaller pre-tympanic one, 

 and a larger post-tympanic or hyoid nerve, which 

 supplies the- muscles of the hyoid and the floor of 

 the mouth. 



8. The Auditorii 



arise in common with the foregoing. Each divides 



